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Maternal obstetric paralysis
Maternal obstetric paralysis EDWARD C. HILL, M.D. San Francisco, California
I N T H E newborn infant, brachial palsy and paralysis of the facial muscles are well known to the obstetrician, and the mechanisms of these injuries have been well established. In the mother, however, nerve damage resulting in paralysis or paresis of various muscle groups of the lower extremity has received little attention, and there appears to be disagreement as to the dynamics of this type of injury. A review of the condition and a discussion of 5 cases from the University of California Hospital may be helpful in elucidating some of the circumstances in which this complication of childbirth may occur.
passed over after a cursory examination and go unrecognized as nerve injuries associated with childbirth. Undoubtedly this condition occurs in minor degree more often than is generally recognized. There are several theories regarding the etiology of nerve injury in pregnancy with paralysis or weakness of the lower extremities. The first of these, credited to Bianchi in 1876 and later advanced by Hiinermann 4 in 1892, was that the injury was due to compression of the lumbosacral trunk against the bony pelvis by the descending fetal head. The lumbosacral cord or trunk carries fibers from the nerve roots of L-4 and L-5 to the sacral plexus, but in order to reach the plexus it must cross the pelvic inlet, lying on the sacral ala at a point at which it is completely exposed (Fig. 1). Having emerged from beneath the protective covering, it is not cushioned by the psoas muscle. With those from the sacral segments, the nerve fibers from these lumbar segments contribute to the formation of the sciatic nerve. This nerve, through its major branches, the tibial and common peroneal nerves, supplies nearly the entire skin of the leg as well as the muscles at the back of the thigh and those of the leg and the foot (Fig. 2). The muscles most often involved in the paresis or paralysis are those supplied by the common peroneal division of the sciatic nerve-the dorsiflexor muscles of the ankle and the extensor muscles of the toes. It has been postulated that this more frequent involvement is related to the fact that the fibers destined to form a portion of this nerve lie posterior to those contributing to the tibial nerve and, therefore, lie directly
Incidence and etiology
In 1949 a review of the literature by Chalmers1 showed 146 cases reported to that time. The incidence for this complication of childbirth has been recorded from 1:2,600 deliveries 2 to 1:6,400 deliveries. 3 At the University of California Hospital, the 5 cases occurred in an interval during which there were 13,093 deliveries, an incidence of 1:2,600. When encountered clinically, gross paralysis or marked paresis of any major muscle or muscle group is obvious and is sufficiently alarming to the obstetrician to be recorded. Minor derangements, on the other hand, when brought to the attention of the attending physician, are frequently
From the Department of Obstetrics and Gynecology, University of California School of Medicine. Presented by invitation at the Twenty-eighth Annual Meeting of the Pacific Coast Obstetrical and Gynecological Society, Yosemite National Park, California, Sept. 20-23, 1961.
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Maternal obstetric paralysis
against bone and are more likely to be traumatized. 5 The tibial nerve, which is also occasionally involved, supplies the plantar flexors of the ankle. Sensory disturbances in general follow the same distribution as do the motor disturbances, although occasionally there is a peculiar combination of both. Kleinberg's 6 explanation for this is the varying pressures exerted on different portions of the lumbosacral cord. Lambrinudi,t in 1924, pointed out several discrepancies in the lumbosacral cord compression theory. He pointed out that this theory failed to explain those unusual cases of obstetric paralysis which were bilateral; that paralysis occasionally involved structures supplied by the femoral nerve which could not possibly be in jured by pressure from the fetal head or be subject to trauma by obstetric forceps; that paralysis not infrequently occurred following normal spontaneous deliveries in which there was no evidence of disproportion; and that pain of a sciatic distribution was frequently encountered in pregnant patients. He felt that injury to the lumbosacral cord was more likely due to traction. It was his belief that during pregnancy, and particularly during labor, there is a backward rotation of the sacrum, which places the already taut lumbosacral nerve on a stretch. This, ac-
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cording to the theory, would be of particular significance in cases with cephalopelvic disproportion, where the degree of rotation may be considerable. Although it has been assumed that the lumbosacral cord could also be injured by the obstetric forceps, it remained for Beattie, 8 in 1933, to demonstrate how easily the forceps blade could damage this structure. By using a fetus and a dissected pelvis, he demonstrated that in occipitoposterior and transverse positions, the nerve is in very close relationship to the broad occipital portion of the fetal head and that, where there is some disproportion at the inlet, nerve injury due to compression can easily occur. He showed further that it is virtually impossible for any portion of the fetal skull, other than the broad occiptal end, to exert undue pressure at the brim of the pelvis. In 2 of his reported cases, in which the in jury was on
L-1.
Fig. 1. The lumbosacral trunk, carrying fibers from the nerve roots of L-4 and L-5, crosses the pelvic brim on the sacral ala, where it is exposed either to compression by the fetal head or to the tip of the obstetric forceps.
Fig. 2. The scmtlc nerve, through its major branches, the tibial and common peroneal nerves, supplies nearly the entire skin of the leg as well as the muscles at the back of the thigh and those of the leg and foot.
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the side opposite that occupied by the occiput, the forceps blades were held responsible. Tillman 2 in 1935 and Cole 3 in 1946 directed attention to the fact that these injuries were more likely to occur in patients in whom the sacral ala has a very shallow anterior concavity and in whom the sacral promontory does not project significantly into the birth canal. Under these conditions, the protection afforded by bony prominences on either side of the nerve is lost and the nerve is vulnerable to injury either by compression between the fetal head and the bony pelvis or by an errant forceps blade. Chalmers 1 has indicated that forceps trauma to the lumbosacral trunk probably represents the commonest mechanism of injury, and this seems to be borne out by our experiences. In 1944 O'ConnelJ9 again reviewed the problem of maternal obstetric paralysis and introduced yet another theory of etiology. It was his contention that a certain proportion of these are related to protrusion of an intervertebral disc. This theory is supported with a report of 4 cases, in each of which the diagnosis was confirmed at operation. There is an increased incidence of herniated disc during pregnancy, due perhaps to the effects of relaxin on the joint structure of the intervertebral spaces, the changing posture of the pregnant woman, and the physical strain during labor. O'Connell's theory could explain the very unusual instances of femoral nerve involvement, with pain in the anterior aspect of the thigh and paralysis of the quadriceps femoris muscle. It could also explain paralysis of a sciatic distribution. Rare cases of paraplegia after labor could be explained on the basis of a very large disc protrusion. Because the interspace most often involved in disc protrusions is that between L-5 and S-1, the symptoms and signs usually are those of a sciatic distribution. The resultant clinical picture is that of sciatic pain and gross muscle weakness in the distribution of the sciatic nerve. Should the herniation lie between L-2 and L-3 or
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Am. J. Obst. & Gynec.
between L-3 and L-4, however, the roots of the femoral nerve may become involved with the corresponding clinical picture. Brief mention should also be made of nerve injuries which occur as a result of faulty technique in placing the patient m lithotomy position on the delivery table. A. badly adjusted leg stirrup may cause cornpression of the common peroneal nerve at the point where it winds around the neck of the fibula. This type of nerve injury mav well be on the basis of impairment in the blood supply to the nerve, hence due to anoxia rather than actual physical disruption of nerve fibers. Clinical picture
As indicated, the signs and symptoms of maternal obstetric paralysis are not constant, but rather depend upon the location, the degree, and the extent of nerve injury. The majority of patients with this condition will be primiparas upon whom a forceps delivery has been carried out following a relatively prolonged or difficult labor. For many, there may have been an expectation of difficulty because of antepartum borderline pelvic measurements, and in these patients, x-ray pelvimetry may have been done. Within a day or two following delivery, symptoms appear. Usually there will be complaints of pain, numbness or tingling, and a sense of heaviness or weakness in one leg. The gait may show a decided limp, and in severe cases it may be of the steppage variety. Careful examination will reveal areas of diminished pain and touch sensation, as well as weakness or paralysis of various muscle groups. The extensors of the toes and the dorsiflexors of the ankle are most often involved, with varying degrees of foot drop. Case reports
Case 1. M. R., a 28-year-old primigravida, had a contracted outlet measured clinically. The pubic arch was narrow with a hi-ischial diameter of 7 em. and a posterior sagittal diameter at the outlet of 7 em. X-ray pelvimetry demonstrated a true conjugate diameter of 10.5 em. and a
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transverse diameter of the inlet of 12.2 em. The sacral promontory was flattened and the sacral alae were shallow. The interspinous diameter was 9.5 em., with a posterior sagittal diameter at the midplane of 5 em. After the patient had been in labor 18 hours ( 2 hours in second stage) , the vertex presented in left occipitoanterior position at station plus-3. A low forceps delivery of a 3,300 gram male infant was accomplished without difficulty. On the first postpartum day, a right foot drop was noted. There was diminished sensation to touch and to pinprick over the anterolateral aspect of the right foot, the ankle, and the plantar surfaces; marked weakness of the muscles supplied by the common peroneal nerve; and moderate weakness of the calf muscles, the hip abductors, and internal rotators. She left the hospital with a brace for foot drop. Four months later there was no evidence of residual impairment. Case 2. N. L., a 17 -year-old primigravida with a clinically normal pelvis, entered the labor room at term with a vertex presentation unengaged. X-ray pelvimetry (Fig. 3) at that time showed an inlet with a true conjugate diameter of 12 em. and a transverse diameter of 11.4 em. The sacral promontory was quite flat, with shallow sacral alae. The interspinous diameter measured 9.4 em. and the posterior sagittal diameter of the midplane was 3.8 em. A diagnosis of midpelvic contraction was made, and a trial of labor was begun. After 7 hours of labor, the cervix was completely dilated and the vertex at the level of the ischial spines was in right occipitotransverse position. Following 4)/2 hours of second-stage labor, a difficult midforceps delivery of a 3,720 gram female infant was accomplished from the right occipitatransverse position. Post partum she complained of numbness and weakness of the left leg below the knee. Examination revealed hypalgesia of the lateral surface of the left leg and foot. There was a distinct weakness of the extensor hallucis longus as \vell as of the gastrocnemius and plantaris muscles, and the patient walked with a limp. Six weeks post partum there was little residual weakness, but she still complained of numbness in the lateral aspect of the foot. Fourteen months later, this patient was delivered again, this time spontaneously, of a 3,270 gram male infant after 5 hours of labor. There were no neurological sequelae.
Case 3. L. C., a 28-year-old primigravida with a clinically normal pelvis, was admitted in prodromal labor with a vertex presentation not engaged. After 12 hours of first-stage labor, the fetal head had descended to 3 em. below the level of the ischial spines in right occipitoposterior position. After 4 hours of second-stage labor, without change in the station or position of the presenting part, a difficult forceps delivery of a 3,050 gram female infant was effected. On the day foliowing delivery the patient complained of numbness and weakness of the left ankle. Examination revealed no objective sensory changes, but there was a distinct weakness in the dorsiflexors of the ankle. Six months post partum the paresis had largely cleared, hut there were continued subjective paresthesias in the lateral aspect of the lower leg and foot. Case 4. D. S., was a 30-year-old primigravida with a diagonal conjugate measurement of 11.75 em. X-ray pelvimetry revealed a true conjugate diameter of 9.8 ern., with a transverse diameter of 11.8 em. The interspinous measurement was 10.4 em., and the posterior sagittal diameter of the midplane was 4.4 em. Following 12 hours of labor, a 2,930 gram female infant was delivered from the left occipitotransverse position with a classical forceps. The application of thr forceps and the delivery wrre described as ha\'ing been accomplished with ease. On the day of delivery she 1omplained of ... r pam m tne ngnt teg ana couta nm ratse n rr
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Fig. 3. Case 2. Inlet view, demonstrating shallow sacral alae and a flat sacral promontory. Midpelvic contraction was noted. Following a prolonged second-stage labor, a difficult midforceps delivery of a 3,720 gram male infant was accomplished from right occipitotransverse position. Considerable manipulation of the forceps blade in the hollow of the sacrum was considered responsible for a left-sided nerve lesion .
out from the left occipitotransverse position, station plus-3. Several hours after delivery she complained of numbness and weakness of the right leg. Neurological examination revealed marked weakness in the hamstring muscles of the right thigh, as well as a foot drop and weakness of plantar flexion. There was decreased vibratory and position sense distally to the upper one third of the calf, as well as dysesthesia to pain stimuli and light touch to a level just below the knee. X-ray pelvimetry after the injury revealed a true conjugate diameter of 10.7 em. with a transverse diameter of the inlet of 11.5 em. The interspinous measurement was 9.4 em. with a posterior sagittal diameter of 3.9 em . One month post partum , although the right leg was stronger, she walked with a limp, and there was residual hypesthesia in the lower one third of the right leg and lateral side of the foot. Weakness of the dorsiflexor muscles of the ankle persisted.
Comment
In Case 1 the greatest diameter of the fetal head had descended on the left side of the maternal pelvis, whereas the injury
June I, 1962 Am. ]. OI>St. & Gyncc.
occurred on the right side. In the light of the left occipital position, it is difficult to ascribe this injury to compression of th e right lumbosacral trunk against the hony pelvis by the fetal head. Despite the ease with which instrumental delivery was effected, it is reasonable to assume in this instance that the forceps blade was the responsible force in the injury to the nerve. The involvement of the hip muscles rul~s against a diagnosis of stirrup pressure against the peroneal nerve. Several attempts were made to apply forceps to the fetal head by wandering th e blade in the hollow of the sacrum in Case 2. The injury occurred on the side opposite the position of the fetal occiput. This was a difficult midforceps delivery, and the nerve injury was attributed to the forceps blade rather than to compression by the fetal head . A second delivery of this patient took place without difficulty, and there were no com plications. Although Tillman 2 recommends that a multipara who presents a history of recovery from an obstetric nerve injury should be subsequently delivered by cesarean section, this case illustrates that this dictum cannot be applied in general. Undoubtedly the difference in feta l size in th~ second pregnancy contributed greatly to the ease of the second delivery. We subscribe to the advice of Cole 3 that subsequent pregnancies should be carefully evaluated, and, if there is likelihood of repeat injury, cesarean section should be consider~d. Again, in Case 3, there was extensive forceps manipulation in the pelvis with unsuccessful attempts to wander the anterior blade of the Kielland forceps into position around the infant's face. The Barton forceps were applied with difficult y. As in the previous cases, the injury occurred on the side opposite that occupied by the broad occipital portion of the fetal head . The most likely explanation for the neurological injury is that of forceps blade trauma, rather than simple cord compression by the fetal skull. Because the patient in Case 4 had a flat pelvis and an easy forceps delivery, it is tempting to postulate that the injury was
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the result of nerve compression by the fetal head. On the other hand, the position was left occipitotransverse and the lesion was right-sided. Again, the anterior blade of the forceps was wandered over the infant's face on the right side of the maternal pelvis. This injury, therefore, probably represents one caused by forceps, even though the delivery was accomplished without difficulty. In Case 5 also, the fetal occiput occupied the left side of the pelvis, the forceps blade was wandered in its application around the right side of the pelvis, and the nerve injury occurred on the right side. The obstetric forceps would appear to be implicated as the cause of this neurological injury. All of these cases, then, probably represent in jury by the forceps blades to the lumbosacral trunk or sacral plexus. The relationship of the trunk, as it crosses the brim of the pelvis, to the tip of the forceps can be seen in Fig. +. All of the in juries occurred in primigravidas. Pelvic x-ray films of 4 of the 5 patients demonstrated sacral alae which were relatively flat with little protection afforded by a well-formed sacral promontory. Four of the 5 deliveries involved prolongations of the second stage of labor, and in 3 deliveries the forceps application was described as difficult. To ascribe any one of these cases to traction on the lumbosacral cord due to backward rotation of the sacrum would seem to ignore a more obvious cause. The occurrence of the injury on the side opposite the occiput in each instance rules out compression of the nerve root against the sacrum by the fetal head. To postulate herniated intervertebral discs compressing nerve roots seems untenable. It is more likely that the forceps blade was the trauma-producing force in each instance, and the maneuver of wandering the blade through the hollow of the sacrum is a particularly hazardous one when the bony characteristics of the pelvis are those described above. In view of this, one is inclined to echo Beattie's statement of 25 years ago, that it is quite remarkable that the lesion does not occur more frequently than it does in cases of forceps delivery. 8
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Treatment and prognosis
Immediate treatment consists of proper splinting or bracing of the foot to prevent plantar flexion deformities. Physiotherapy in the form of gentle massage and passive motion initially, with galvanic stimulation later, constitutes the most important part of active therapy, in order to prevent muscular atrophy and contractions, pending regeneration of nerve tissue. The prognosis for complete recovery for most patients is good, but one must exercise considerable caution in early prognostication, for it is difficult to assess the degree and extent of the damage until the patient has continued under observation for some months. Recovery may take as long as 2 years following the injury, but fortunately in most patients it is usually a complete one. Summary
1. Five cases of maternal obstetric paralysis are reported from the University of California Hospital, San Francisco. These occurred in the performance of 13,093 deliveries for an incidence of 1:2,600. 2. Of the several etiological theories proposed, the most common method of nerve injury appears to be that of lumbosacral cord trauma by the obstetric forceps . 3. The typical situation in which maternal obstetric paralysis occurs is in a prolonged labor necessitating forceps delivery in a
Fig. 4. Dissection demonstrating the relationship between the lumbosacral trunk and the tip of th e obstetric forceps blade. The posterior parietal p eritoneum and the common iliac vessels have been removed.
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primigravid patient with shallow sacral alae and a sacral promontory which does not project significantly into the birth canal. Wandering the anterior blade through the hollow of the sacrum is a particularly hazardous maneuver in this circumstance. 4. Clinically the nerve injury is most often manifest by pain and muscle weakness in
Am.
the distribution of the the common peroneal tensively involved. Foot finding. 5. Treatment consists vent contracture and prevent muscle atrophy generation.
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June I, 1962 Obst. & Gynec.
sciatic nerve, with branch more exdrop is a frequent of bracing to prephysiotherapy to pending nerve rP-
REFERENCES
1. Chalmers, J. A.: J. Obst. & Gynaec. Brit. Emp. 56: 205, 1949. 2. Tillman, A. J. B.: AM. J. 0BST. & GYNEC. 29: 660, 1935. 3. Cole, J. T.: AM. J. OBsT. & GYNEC. 52: 373, 1946. 4. Hiinermann: Arch. Gynak. 42: 489, 1892. 5. Thomas, H. M.: Johns Hopkins Hosp. Bull. 11: 279, 1900.
Discussion DR. RALPH C. WALKER, North Hollywood, California. I am not able to confirm or give an estimate of the incidence of nerve injury. At Saint Joseph Hospital there were no reported cases and none in the last 2 or 3 years at the Los Angeles County General Hospital. Considering the volume of obstetric cases, minor injuries may have occurred and have been overlooked. but no serious paralysis was recorded. In recent years the frequency of litigation, particularly in cases involving demonstrable injury or unsatisfactory result, has made physicians cautious in placing blame on any activity or injury that could be ascribed to human error. Also, patients have a tendency to believe that their backaches or other discomforts are dated from and directly due to a previous spinal or block anesthesia. If a case of foot drop or paralysis occurs, and the patient has received regional anesthesia, this will probably be accepted as the cause by the patient. In 1957, Drs. Robert Cosgrove and Owens Weaver, at the Margaret Hague Memorial Hospital, reported a series of 1,000 midforceps deliveries (670 for dystocia)-182 of these were the low midforceps level. There were 96 different operators-a total incidence of 1.9 per cent. One case of foot drop was recorded, which raises the question of why, if this is primarily a forceps injury, it does not happen more often? Anatomically the lumbosacral plexus is lightly
6. Kleinberg, S.: Surg. Gynec. & Obst. 45: 61, 1927. 7. Lambrinudi, C.: Brit. ]. Surg. 12: 554, 1925. 8. Beattie, W. J. H. M.: St. Barth. Hosp. Rep. 66: 171, 1933. 9. O'Connell, J. E. A.: Surg. Gynec. & Obst. 79: 374, 1944.
protected as it crosses the brim of the pelvis. I am sure all have observed the thigh and leg reflex that is associated with forceps delivery, as the fetal head sharply rotates from an oblique to an occipitoanterior position. This is likely particularly to be noted in pelves with prominent ischial spines, an observation which would tend to confirm Dr. Hill's theory of a forceps injury. To ascribe the injury to the wandering of the forceps blade in the midpelvis is not unreasonable, although one would expect injury at this level to be extensive. Other causes for injury must be considered, such as inlet contractures with compression of the fetal head against tlw ala of the sacrum and the lumbosacral joint. excessive backward rotation of the sacrum, disc protrusion, contact injury, and tight leg stirrups. Careful placing of the patient on the delivery table and padding of contact points is important to prevent postpartum discomfort, as well as the more rare nerve injury. DR. CARL GoETSCH, Berkeley, California. About 1Yz or 2 years ago I had a patient who had an irregular pelvis. The head was directly posterior, and as I did the rotation she gave a twitch with her left leg. She developed a foot drop and some paresthesia. The paresthesias cleared rather promptly, but the foot drop did not clear up for about 3 months, so that that record was very well documented from the medicolegal standpoint.
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I would make one comment on Dr. Walker's discussion. In Alameda County we have a philosophy that if we are wrong we will pay off; if we are right we will fight to the death. So that if there is a true negligence in the use of the forceps and a paralysis ensues, then we would attempt a settlement. If paralysis follows application of forceps, this can be recognized, but it can be defended, certainly, on the grounds that this was an indicated and well-applied forceps delivery. DR. RrcHARD L. TAw, Los Angeles, California. There is another nerve that occasionally is injured in obstetric and gynecologic proceduresthe femoral nerve. My interest in this developed when I had 3 cases in a little over 3 months. One of them fortunately turned out to be a case of multiple sclerosis, and it seemed to be coincidental that this femoral nerve injury and the multiple sclerosis became evident the same time. The other 2 cases followed vaginal procedures, one curettage and one vaginal hysterectomy. It would take a very long curette or very long pair of scissors to injure a femoral nerve with a vaginal procedure. I went to the anatomy room. and dissected a femoral nerve. The nerve is fairly well protected and is ordinarily out of the true pelvis. I think that position and traction on the nerve were responsible. This traction either injures the nerve directly or through the blood supply. At about this same time Dr. Judd became interested in a case that was up for litigation, a femoral nerve injury following an abdominal procedure. The operator habitually put the Balfour retractor in upside down, with the middle blade toward the umbilicus. This positioning of the blade places the lateral tips of the Balfour retractor directly over the femoral nerve so that any downward pressure is directly on the femoral nerve. Since then I certainly have had no inclination personally to turn a Balfour retractor around. I think that some anatomic anomalies may be involved, since these nerves are so infrequently injured. DR. GEORGE E. JUDD, Los Angeles, California. In the case that Dr. Taw mentioned, the doctor had had a neuromyograph done on the injured or the disturbed musculature, and it showed that this was not a complete but a partial injury of the nerve. In other words, all of the axons were
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not broken or injured; there were some that were alive. This type of injury comes more from a stretch than it does from a blow or from something which can compress it, as a ligature might be put around a nerve. The time in which this paralysis develops is important. If this injury develops at the time of delivery, this patient should show the injury within 24 hours. If it develops later, it is not an injury directly related to delivery. If you do have a patient that develops a paralysis, obtain a neuromyograph because it will tell you if this is a direct injury to the nerve or one that might be developed by stretching. We were able in this particular case to show that this injury came about mainly by stretching and that this patient had been up and around for a full 24 hours without injury. She may have fallen or may have stretched this nerve by hyperextension of the sciatic trunk. DR. KEITH P. RussELL, Los Angeles, California. The transverse incision seems sometimes to lead to the type of nerve injury that has been suggested by Dr. Taw and Dr. Judd. This question was posed to the International Correspondence Society, and those of you who subscribe to this will see the various answers. At any rate it is important to realize that the transverse incision allows much wider latitude. If you use an O'Connor-Sullivan retractor, or one of that type, if it is in position for quite a while, you may find some degree of nerve damage, which again is due to pressure or stretching. The most common manifestation is an area of anesthesia or paresthesia on the anterior lateral surface of the thigh. Many patients will complain of this for some time. It always clears. Sometimes it takes from 6 to 8 weeks or more to do so, but the adjustment of the retractor is an important consideration. DR. EDMUND W. OVERSTREET, San Francisco, California. I would like to add one more point to the medicolegal situation with regard to these injuries because it has come up over and over again in our work on the County Medical Review Advisory Committee. There is still a tremendous tendency among physicians to minimize this type of injury to the patient. This, of course, is a very serious error, and the patient should be fully informed of all the possibilities immediately after they come to our attention. The important thing to remember is that the
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statute of limitations does not begin to run until the patient is so informed. DR. HILL (Closing). Living and practtcmg in California, I am as aware as any of you of the possible legal aspects of this injury. I am sure that all of you would agree, however, that in a society such as this we are all seeking the truth. There is no question that this injury can occur as a result of forceps application. There is no question at the same time, however, that the injury can occur in a perfectly normal spontaneous delivery. True, it is more likely to occur where there is some cephalopelvic disproportion; but in a flat pelvis, with molding of the head, it is entirely possible for the nerve to be injured simply by a compression between the fetal head and the bony pelvis. So far as the anesthetics in our cases are concerned, 2 of these deliveries were accomplished under spinal anesthesia and 3 were done
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under pudendal block anesthesia. The incidence in Los Angeles apparently is very small. In the Union of South Africa, however, a series of 20 cases was reported by Sinclair in 1956, and it was interesting to note that I ti of these occuned within one year in one hospital, with a delivery of 7,000 patients in that one year. Many of these were spontaneous deliveries, rather than forceps. So far as femoral nerve injury is concerned, it is almost impossible to injure the femoral nerve with the obstetric forceps. If such an instance were encountered, I would suspect very strongly that the patient had herniated an intervertebral disc at a level higher than L-5 and S-1 because the femoral nerve gets its nerve roots from the higher lumbar segments. Herniated intervertebral disc is more likely to ocrur in women and, frankly, dates from the tim<~ of delivery. It is easy to visualize how, with the straining in the second stage of labor. a patient might herniate an intervertebral disc.
I N T H E newborn infant, brachial palsy and paralysis of the facial muscles are well known to the obstetrician, and the mechanisms of these injuries have been well established. In the mother, however, nerve damage resulting in paralysis or paresis of various muscle groups of the lower extremity has received little attention, and there appears to be disagreement as to the dynamics of this type of injury. A review of the condition and a discussion of 5 cases from the University of California Hospital may be helpful in elucidating some of the circumstances in which this complication of childbirth may occur.
passed over after a cursory examination and go unrecognized as nerve injuries associated with childbirth. Undoubtedly this condition occurs in minor degree more often than is generally recognized. There are several theories regarding the etiology of nerve injury in pregnancy with paralysis or weakness of the lower extremities. The first of these, credited to Bianchi in 1876 and later advanced by Hiinermann 4 in 1892, was that the injury was due to compression of the lumbosacral trunk against the bony pelvis by the descending fetal head. The lumbosacral cord or trunk carries fibers from the nerve roots of L-4 and L-5 to the sacral plexus, but in order to reach the plexus it must cross the pelvic inlet, lying on the sacral ala at a point at which it is completely exposed (Fig. 1). Having emerged from beneath the protective covering, it is not cushioned by the psoas muscle. With those from the sacral segments, the nerve fibers from these lumbar segments contribute to the formation of the sciatic nerve. This nerve, through its major branches, the tibial and common peroneal nerves, supplies nearly the entire skin of the leg as well as the muscles at the back of the thigh and those of the leg and the foot (Fig. 2). The muscles most often involved in the paresis or paralysis are those supplied by the common peroneal division of the sciatic nerve-the dorsiflexor muscles of the ankle and the extensor muscles of the toes. It has been postulated that this more frequent involvement is related to the fact that the fibers destined to form a portion of this nerve lie posterior to those contributing to the tibial nerve and, therefore, lie directly
Incidence and etiology
In 1949 a review of the literature by Chalmers1 showed 146 cases reported to that time. The incidence for this complication of childbirth has been recorded from 1:2,600 deliveries 2 to 1:6,400 deliveries. 3 At the University of California Hospital, the 5 cases occurred in an interval during which there were 13,093 deliveries, an incidence of 1:2,600. When encountered clinically, gross paralysis or marked paresis of any major muscle or muscle group is obvious and is sufficiently alarming to the obstetrician to be recorded. Minor derangements, on the other hand, when brought to the attention of the attending physician, are frequently
From the Department of Obstetrics and Gynecology, University of California School of Medicine. Presented by invitation at the Twenty-eighth Annual Meeting of the Pacific Coast Obstetrical and Gynecological Society, Yosemite National Park, California, Sept. 20-23, 1961.
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Maternal obstetric paralysis
against bone and are more likely to be traumatized. 5 The tibial nerve, which is also occasionally involved, supplies the plantar flexors of the ankle. Sensory disturbances in general follow the same distribution as do the motor disturbances, although occasionally there is a peculiar combination of both. Kleinberg's 6 explanation for this is the varying pressures exerted on different portions of the lumbosacral cord. Lambrinudi,t in 1924, pointed out several discrepancies in the lumbosacral cord compression theory. He pointed out that this theory failed to explain those unusual cases of obstetric paralysis which were bilateral; that paralysis occasionally involved structures supplied by the femoral nerve which could not possibly be in jured by pressure from the fetal head or be subject to trauma by obstetric forceps; that paralysis not infrequently occurred following normal spontaneous deliveries in which there was no evidence of disproportion; and that pain of a sciatic distribution was frequently encountered in pregnant patients. He felt that injury to the lumbosacral cord was more likely due to traction. It was his belief that during pregnancy, and particularly during labor, there is a backward rotation of the sacrum, which places the already taut lumbosacral nerve on a stretch. This, ac-
1453
cording to the theory, would be of particular significance in cases with cephalopelvic disproportion, where the degree of rotation may be considerable. Although it has been assumed that the lumbosacral cord could also be injured by the obstetric forceps, it remained for Beattie, 8 in 1933, to demonstrate how easily the forceps blade could damage this structure. By using a fetus and a dissected pelvis, he demonstrated that in occipitoposterior and transverse positions, the nerve is in very close relationship to the broad occipital portion of the fetal head and that, where there is some disproportion at the inlet, nerve injury due to compression can easily occur. He showed further that it is virtually impossible for any portion of the fetal skull, other than the broad occiptal end, to exert undue pressure at the brim of the pelvis. In 2 of his reported cases, in which the in jury was on
L-1.
Fig. 1. The lumbosacral trunk, carrying fibers from the nerve roots of L-4 and L-5, crosses the pelvic brim on the sacral ala, where it is exposed either to compression by the fetal head or to the tip of the obstetric forceps.
Fig. 2. The scmtlc nerve, through its major branches, the tibial and common peroneal nerves, supplies nearly the entire skin of the leg as well as the muscles at the back of the thigh and those of the leg and foot.
1454 Hill
the side opposite that occupied by the occiput, the forceps blades were held responsible. Tillman 2 in 1935 and Cole 3 in 1946 directed attention to the fact that these injuries were more likely to occur in patients in whom the sacral ala has a very shallow anterior concavity and in whom the sacral promontory does not project significantly into the birth canal. Under these conditions, the protection afforded by bony prominences on either side of the nerve is lost and the nerve is vulnerable to injury either by compression between the fetal head and the bony pelvis or by an errant forceps blade. Chalmers 1 has indicated that forceps trauma to the lumbosacral trunk probably represents the commonest mechanism of injury, and this seems to be borne out by our experiences. In 1944 O'ConnelJ9 again reviewed the problem of maternal obstetric paralysis and introduced yet another theory of etiology. It was his contention that a certain proportion of these are related to protrusion of an intervertebral disc. This theory is supported with a report of 4 cases, in each of which the diagnosis was confirmed at operation. There is an increased incidence of herniated disc during pregnancy, due perhaps to the effects of relaxin on the joint structure of the intervertebral spaces, the changing posture of the pregnant woman, and the physical strain during labor. O'Connell's theory could explain the very unusual instances of femoral nerve involvement, with pain in the anterior aspect of the thigh and paralysis of the quadriceps femoris muscle. It could also explain paralysis of a sciatic distribution. Rare cases of paraplegia after labor could be explained on the basis of a very large disc protrusion. Because the interspace most often involved in disc protrusions is that between L-5 and S-1, the symptoms and signs usually are those of a sciatic distribution. The resultant clinical picture is that of sciatic pain and gross muscle weakness in the distribution of the sciatic nerve. Should the herniation lie between L-2 and L-3 or
June 1, 1962
Am. J. Obst. & Gynec.
between L-3 and L-4, however, the roots of the femoral nerve may become involved with the corresponding clinical picture. Brief mention should also be made of nerve injuries which occur as a result of faulty technique in placing the patient m lithotomy position on the delivery table. A. badly adjusted leg stirrup may cause cornpression of the common peroneal nerve at the point where it winds around the neck of the fibula. This type of nerve injury mav well be on the basis of impairment in the blood supply to the nerve, hence due to anoxia rather than actual physical disruption of nerve fibers. Clinical picture
As indicated, the signs and symptoms of maternal obstetric paralysis are not constant, but rather depend upon the location, the degree, and the extent of nerve injury. The majority of patients with this condition will be primiparas upon whom a forceps delivery has been carried out following a relatively prolonged or difficult labor. For many, there may have been an expectation of difficulty because of antepartum borderline pelvic measurements, and in these patients, x-ray pelvimetry may have been done. Within a day or two following delivery, symptoms appear. Usually there will be complaints of pain, numbness or tingling, and a sense of heaviness or weakness in one leg. The gait may show a decided limp, and in severe cases it may be of the steppage variety. Careful examination will reveal areas of diminished pain and touch sensation, as well as weakness or paralysis of various muscle groups. The extensors of the toes and the dorsiflexors of the ankle are most often involved, with varying degrees of foot drop. Case reports
Case 1. M. R., a 28-year-old primigravida, had a contracted outlet measured clinically. The pubic arch was narrow with a hi-ischial diameter of 7 em. and a posterior sagittal diameter at the outlet of 7 em. X-ray pelvimetry demonstrated a true conjugate diameter of 10.5 em. and a
Maternal obstetric paralysis 1455
Volume 83 Number 11
transverse diameter of the inlet of 12.2 em. The sacral promontory was flattened and the sacral alae were shallow. The interspinous diameter was 9.5 em., with a posterior sagittal diameter at the midplane of 5 em. After the patient had been in labor 18 hours ( 2 hours in second stage) , the vertex presented in left occipitoanterior position at station plus-3. A low forceps delivery of a 3,300 gram male infant was accomplished without difficulty. On the first postpartum day, a right foot drop was noted. There was diminished sensation to touch and to pinprick over the anterolateral aspect of the right foot, the ankle, and the plantar surfaces; marked weakness of the muscles supplied by the common peroneal nerve; and moderate weakness of the calf muscles, the hip abductors, and internal rotators. She left the hospital with a brace for foot drop. Four months later there was no evidence of residual impairment. Case 2. N. L., a 17 -year-old primigravida with a clinically normal pelvis, entered the labor room at term with a vertex presentation unengaged. X-ray pelvimetry (Fig. 3) at that time showed an inlet with a true conjugate diameter of 12 em. and a transverse diameter of 11.4 em. The sacral promontory was quite flat, with shallow sacral alae. The interspinous diameter measured 9.4 em. and the posterior sagittal diameter of the midplane was 3.8 em. A diagnosis of midpelvic contraction was made, and a trial of labor was begun. After 7 hours of labor, the cervix was completely dilated and the vertex at the level of the ischial spines was in right occipitotransverse position. Following 4)/2 hours of second-stage labor, a difficult midforceps delivery of a 3,720 gram female infant was accomplished from the right occipitatransverse position. Post partum she complained of numbness and weakness of the left leg below the knee. Examination revealed hypalgesia of the lateral surface of the left leg and foot. There was a distinct weakness of the extensor hallucis longus as \vell as of the gastrocnemius and plantaris muscles, and the patient walked with a limp. Six weeks post partum there was little residual weakness, but she still complained of numbness in the lateral aspect of the foot. Fourteen months later, this patient was delivered again, this time spontaneously, of a 3,270 gram male infant after 5 hours of labor. There were no neurological sequelae.
Case 3. L. C., a 28-year-old primigravida with a clinically normal pelvis, was admitted in prodromal labor with a vertex presentation not engaged. After 12 hours of first-stage labor, the fetal head had descended to 3 em. below the level of the ischial spines in right occipitoposterior position. After 4 hours of second-stage labor, without change in the station or position of the presenting part, a difficult forceps delivery of a 3,050 gram female infant was effected. On the day foliowing delivery the patient complained of numbness and weakness of the left ankle. Examination revealed no objective sensory changes, but there was a distinct weakness in the dorsiflexors of the ankle. Six months post partum the paresis had largely cleared, hut there were continued subjective paresthesias in the lateral aspect of the lower leg and foot. Case 4. D. S., was a 30-year-old primigravida with a diagonal conjugate measurement of 11.75 em. X-ray pelvimetry revealed a true conjugate diameter of 9.8 ern., with a transverse diameter of 11.8 em. The interspinous measurement was 10.4 em., and the posterior sagittal diameter of the midplane was 4.4 em. Following 12 hours of labor, a 2,930 gram female infant was delivered from the left occipitotransverse position with a classical forceps. The application of thr forceps and the delivery wrre described as ha\'ing been accomplished with ease. On the day of delivery she 1omplained of ... r pam m tne ngnt teg ana couta nm ratse n rr
•
.1
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1
1
11
,
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1456
Hill
Fig. 3. Case 2. Inlet view, demonstrating shallow sacral alae and a flat sacral promontory. Midpelvic contraction was noted. Following a prolonged second-stage labor, a difficult midforceps delivery of a 3,720 gram male infant was accomplished from right occipitotransverse position. Considerable manipulation of the forceps blade in the hollow of the sacrum was considered responsible for a left-sided nerve lesion .
out from the left occipitotransverse position, station plus-3. Several hours after delivery she complained of numbness and weakness of the right leg. Neurological examination revealed marked weakness in the hamstring muscles of the right thigh, as well as a foot drop and weakness of plantar flexion. There was decreased vibratory and position sense distally to the upper one third of the calf, as well as dysesthesia to pain stimuli and light touch to a level just below the knee. X-ray pelvimetry after the injury revealed a true conjugate diameter of 10.7 em. with a transverse diameter of the inlet of 11.5 em. The interspinous measurement was 9.4 em. with a posterior sagittal diameter of 3.9 em . One month post partum , although the right leg was stronger, she walked with a limp, and there was residual hypesthesia in the lower one third of the right leg and lateral side of the foot. Weakness of the dorsiflexor muscles of the ankle persisted.
Comment
In Case 1 the greatest diameter of the fetal head had descended on the left side of the maternal pelvis, whereas the injury
June I, 1962 Am. ]. OI>St. & Gyncc.
occurred on the right side. In the light of the left occipital position, it is difficult to ascribe this injury to compression of th e right lumbosacral trunk against the hony pelvis by the fetal head. Despite the ease with which instrumental delivery was effected, it is reasonable to assume in this instance that the forceps blade was the responsible force in the injury to the nerve. The involvement of the hip muscles rul~s against a diagnosis of stirrup pressure against the peroneal nerve. Several attempts were made to apply forceps to the fetal head by wandering th e blade in the hollow of the sacrum in Case 2. The injury occurred on the side opposite the position of the fetal occiput. This was a difficult midforceps delivery, and the nerve injury was attributed to the forceps blade rather than to compression by the fetal head . A second delivery of this patient took place without difficulty, and there were no com plications. Although Tillman 2 recommends that a multipara who presents a history of recovery from an obstetric nerve injury should be subsequently delivered by cesarean section, this case illustrates that this dictum cannot be applied in general. Undoubtedly the difference in feta l size in th~ second pregnancy contributed greatly to the ease of the second delivery. We subscribe to the advice of Cole 3 that subsequent pregnancies should be carefully evaluated, and, if there is likelihood of repeat injury, cesarean section should be consider~d. Again, in Case 3, there was extensive forceps manipulation in the pelvis with unsuccessful attempts to wander the anterior blade of the Kielland forceps into position around the infant's face. The Barton forceps were applied with difficult y. As in the previous cases, the injury occurred on the side opposite that occupied by the broad occipital portion of the fetal head . The most likely explanation for the neurological injury is that of forceps blade trauma, rather than simple cord compression by the fetal skull. Because the patient in Case 4 had a flat pelvis and an easy forceps delivery, it is tempting to postulate that the injury was
Volume 83 Number II
the result of nerve compression by the fetal head. On the other hand, the position was left occipitotransverse and the lesion was right-sided. Again, the anterior blade of the forceps was wandered over the infant's face on the right side of the maternal pelvis. This injury, therefore, probably represents one caused by forceps, even though the delivery was accomplished without difficulty. In Case 5 also, the fetal occiput occupied the left side of the pelvis, the forceps blade was wandered in its application around the right side of the pelvis, and the nerve injury occurred on the right side. The obstetric forceps would appear to be implicated as the cause of this neurological injury. All of these cases, then, probably represent in jury by the forceps blades to the lumbosacral trunk or sacral plexus. The relationship of the trunk, as it crosses the brim of the pelvis, to the tip of the forceps can be seen in Fig. +. All of the in juries occurred in primigravidas. Pelvic x-ray films of 4 of the 5 patients demonstrated sacral alae which were relatively flat with little protection afforded by a well-formed sacral promontory. Four of the 5 deliveries involved prolongations of the second stage of labor, and in 3 deliveries the forceps application was described as difficult. To ascribe any one of these cases to traction on the lumbosacral cord due to backward rotation of the sacrum would seem to ignore a more obvious cause. The occurrence of the injury on the side opposite the occiput in each instance rules out compression of the nerve root against the sacrum by the fetal head. To postulate herniated intervertebral discs compressing nerve roots seems untenable. It is more likely that the forceps blade was the trauma-producing force in each instance, and the maneuver of wandering the blade through the hollow of the sacrum is a particularly hazardous one when the bony characteristics of the pelvis are those described above. In view of this, one is inclined to echo Beattie's statement of 25 years ago, that it is quite remarkable that the lesion does not occur more frequently than it does in cases of forceps delivery. 8
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Treatment and prognosis
Immediate treatment consists of proper splinting or bracing of the foot to prevent plantar flexion deformities. Physiotherapy in the form of gentle massage and passive motion initially, with galvanic stimulation later, constitutes the most important part of active therapy, in order to prevent muscular atrophy and contractions, pending regeneration of nerve tissue. The prognosis for complete recovery for most patients is good, but one must exercise considerable caution in early prognostication, for it is difficult to assess the degree and extent of the damage until the patient has continued under observation for some months. Recovery may take as long as 2 years following the injury, but fortunately in most patients it is usually a complete one. Summary
1. Five cases of maternal obstetric paralysis are reported from the University of California Hospital, San Francisco. These occurred in the performance of 13,093 deliveries for an incidence of 1:2,600. 2. Of the several etiological theories proposed, the most common method of nerve injury appears to be that of lumbosacral cord trauma by the obstetric forceps . 3. The typical situation in which maternal obstetric paralysis occurs is in a prolonged labor necessitating forceps delivery in a
Fig. 4. Dissection demonstrating the relationship between the lumbosacral trunk and the tip of th e obstetric forceps blade. The posterior parietal p eritoneum and the common iliac vessels have been removed.
1458 Hill
primigravid patient with shallow sacral alae and a sacral promontory which does not project significantly into the birth canal. Wandering the anterior blade through the hollow of the sacrum is a particularly hazardous maneuver in this circumstance. 4. Clinically the nerve injury is most often manifest by pain and muscle weakness in
Am.
the distribution of the the common peroneal tensively involved. Foot finding. 5. Treatment consists vent contracture and prevent muscle atrophy generation.
J.
June I, 1962 Obst. & Gynec.
sciatic nerve, with branch more exdrop is a frequent of bracing to prephysiotherapy to pending nerve rP-
REFERENCES
1. Chalmers, J. A.: J. Obst. & Gynaec. Brit. Emp. 56: 205, 1949. 2. Tillman, A. J. B.: AM. J. 0BST. & GYNEC. 29: 660, 1935. 3. Cole, J. T.: AM. J. OBsT. & GYNEC. 52: 373, 1946. 4. Hiinermann: Arch. Gynak. 42: 489, 1892. 5. Thomas, H. M.: Johns Hopkins Hosp. Bull. 11: 279, 1900.
Discussion DR. RALPH C. WALKER, North Hollywood, California. I am not able to confirm or give an estimate of the incidence of nerve injury. At Saint Joseph Hospital there were no reported cases and none in the last 2 or 3 years at the Los Angeles County General Hospital. Considering the volume of obstetric cases, minor injuries may have occurred and have been overlooked. but no serious paralysis was recorded. In recent years the frequency of litigation, particularly in cases involving demonstrable injury or unsatisfactory result, has made physicians cautious in placing blame on any activity or injury that could be ascribed to human error. Also, patients have a tendency to believe that their backaches or other discomforts are dated from and directly due to a previous spinal or block anesthesia. If a case of foot drop or paralysis occurs, and the patient has received regional anesthesia, this will probably be accepted as the cause by the patient. In 1957, Drs. Robert Cosgrove and Owens Weaver, at the Margaret Hague Memorial Hospital, reported a series of 1,000 midforceps deliveries (670 for dystocia)-182 of these were the low midforceps level. There were 96 different operators-a total incidence of 1.9 per cent. One case of foot drop was recorded, which raises the question of why, if this is primarily a forceps injury, it does not happen more often? Anatomically the lumbosacral plexus is lightly
6. Kleinberg, S.: Surg. Gynec. & Obst. 45: 61, 1927. 7. Lambrinudi, C.: Brit. ]. Surg. 12: 554, 1925. 8. Beattie, W. J. H. M.: St. Barth. Hosp. Rep. 66: 171, 1933. 9. O'Connell, J. E. A.: Surg. Gynec. & Obst. 79: 374, 1944.
protected as it crosses the brim of the pelvis. I am sure all have observed the thigh and leg reflex that is associated with forceps delivery, as the fetal head sharply rotates from an oblique to an occipitoanterior position. This is likely particularly to be noted in pelves with prominent ischial spines, an observation which would tend to confirm Dr. Hill's theory of a forceps injury. To ascribe the injury to the wandering of the forceps blade in the midpelvis is not unreasonable, although one would expect injury at this level to be extensive. Other causes for injury must be considered, such as inlet contractures with compression of the fetal head against tlw ala of the sacrum and the lumbosacral joint. excessive backward rotation of the sacrum, disc protrusion, contact injury, and tight leg stirrups. Careful placing of the patient on the delivery table and padding of contact points is important to prevent postpartum discomfort, as well as the more rare nerve injury. DR. CARL GoETSCH, Berkeley, California. About 1Yz or 2 years ago I had a patient who had an irregular pelvis. The head was directly posterior, and as I did the rotation she gave a twitch with her left leg. She developed a foot drop and some paresthesia. The paresthesias cleared rather promptly, but the foot drop did not clear up for about 3 months, so that that record was very well documented from the medicolegal standpoint.
Volume 83 Number 11
I would make one comment on Dr. Walker's discussion. In Alameda County we have a philosophy that if we are wrong we will pay off; if we are right we will fight to the death. So that if there is a true negligence in the use of the forceps and a paralysis ensues, then we would attempt a settlement. If paralysis follows application of forceps, this can be recognized, but it can be defended, certainly, on the grounds that this was an indicated and well-applied forceps delivery. DR. RrcHARD L. TAw, Los Angeles, California. There is another nerve that occasionally is injured in obstetric and gynecologic proceduresthe femoral nerve. My interest in this developed when I had 3 cases in a little over 3 months. One of them fortunately turned out to be a case of multiple sclerosis, and it seemed to be coincidental that this femoral nerve injury and the multiple sclerosis became evident the same time. The other 2 cases followed vaginal procedures, one curettage and one vaginal hysterectomy. It would take a very long curette or very long pair of scissors to injure a femoral nerve with a vaginal procedure. I went to the anatomy room. and dissected a femoral nerve. The nerve is fairly well protected and is ordinarily out of the true pelvis. I think that position and traction on the nerve were responsible. This traction either injures the nerve directly or through the blood supply. At about this same time Dr. Judd became interested in a case that was up for litigation, a femoral nerve injury following an abdominal procedure. The operator habitually put the Balfour retractor in upside down, with the middle blade toward the umbilicus. This positioning of the blade places the lateral tips of the Balfour retractor directly over the femoral nerve so that any downward pressure is directly on the femoral nerve. Since then I certainly have had no inclination personally to turn a Balfour retractor around. I think that some anatomic anomalies may be involved, since these nerves are so infrequently injured. DR. GEORGE E. JUDD, Los Angeles, California. In the case that Dr. Taw mentioned, the doctor had had a neuromyograph done on the injured or the disturbed musculature, and it showed that this was not a complete but a partial injury of the nerve. In other words, all of the axons were
Maternal obstetric paralysis
1459
not broken or injured; there were some that were alive. This type of injury comes more from a stretch than it does from a blow or from something which can compress it, as a ligature might be put around a nerve. The time in which this paralysis develops is important. If this injury develops at the time of delivery, this patient should show the injury within 24 hours. If it develops later, it is not an injury directly related to delivery. If you do have a patient that develops a paralysis, obtain a neuromyograph because it will tell you if this is a direct injury to the nerve or one that might be developed by stretching. We were able in this particular case to show that this injury came about mainly by stretching and that this patient had been up and around for a full 24 hours without injury. She may have fallen or may have stretched this nerve by hyperextension of the sciatic trunk. DR. KEITH P. RussELL, Los Angeles, California. The transverse incision seems sometimes to lead to the type of nerve injury that has been suggested by Dr. Taw and Dr. Judd. This question was posed to the International Correspondence Society, and those of you who subscribe to this will see the various answers. At any rate it is important to realize that the transverse incision allows much wider latitude. If you use an O'Connor-Sullivan retractor, or one of that type, if it is in position for quite a while, you may find some degree of nerve damage, which again is due to pressure or stretching. The most common manifestation is an area of anesthesia or paresthesia on the anterior lateral surface of the thigh. Many patients will complain of this for some time. It always clears. Sometimes it takes from 6 to 8 weeks or more to do so, but the adjustment of the retractor is an important consideration. DR. EDMUND W. OVERSTREET, San Francisco, California. I would like to add one more point to the medicolegal situation with regard to these injuries because it has come up over and over again in our work on the County Medical Review Advisory Committee. There is still a tremendous tendency among physicians to minimize this type of injury to the patient. This, of course, is a very serious error, and the patient should be fully informed of all the possibilities immediately after they come to our attention. The important thing to remember is that the
1460 Hill
statute of limitations does not begin to run until the patient is so informed. DR. HILL (Closing). Living and practtcmg in California, I am as aware as any of you of the possible legal aspects of this injury. I am sure that all of you would agree, however, that in a society such as this we are all seeking the truth. There is no question that this injury can occur as a result of forceps application. There is no question at the same time, however, that the injury can occur in a perfectly normal spontaneous delivery. True, it is more likely to occur where there is some cephalopelvic disproportion; but in a flat pelvis, with molding of the head, it is entirely possible for the nerve to be injured simply by a compression between the fetal head and the bony pelvis. So far as the anesthetics in our cases are concerned, 2 of these deliveries were accomplished under spinal anesthesia and 3 were done
:\m.
June I, 196~ & Gynec.
J. Obst.
under pudendal block anesthesia. The incidence in Los Angeles apparently is very small. In the Union of South Africa, however, a series of 20 cases was reported by Sinclair in 1956, and it was interesting to note that I ti of these occuned within one year in one hospital, with a delivery of 7,000 patients in that one year. Many of these were spontaneous deliveries, rather than forceps. So far as femoral nerve injury is concerned, it is almost impossible to injure the femoral nerve with the obstetric forceps. If such an instance were encountered, I would suspect very strongly that the patient had herniated an intervertebral disc at a level higher than L-5 and S-1 because the femoral nerve gets its nerve roots from the higher lumbar segments. Herniated intervertebral disc is more likely to ocrur in women and, frankly, dates from the tim<~ of delivery. It is easy to visualize how, with the straining in the second stage of labor. a patient might herniate an intervertebral disc.