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ACOUSTIC NEUROMA EARLY DIAGNOSIS
[DEC. 11, 1954
ORIGINAL ARTICLES ACOUSTIC NEUROMA EARLY DIAGNOSIS F.R.C.P. CHARINC
CROSS
HOSPITAL, LONDON
WYLIE MCKISSOCK O.B.E., M.S. Lond., F.R.C.S. SURGEON, ST. GEORGE’S HOSPITAL, LONDON
ALTHOUGH acoustic neuromata are surgically accessible and usually benign, the operative mortality in the best hands is not less than 10% (Olivecrona 1940, Horrax and poppen 1939), and recurrences are not uncommon. Moreover, the postoperative morbidity is considerable :
the operation may be followed by facial paralysis, unsteadiness of gait, visual impairment from secondary optic atrophy, and a general malaise which interferes with work and with the enjoyment of life. The main reason for this unsatisfactory state of affairs is that by the time a neuroma has grown large enough to fulfil present diagnostic criteria it has already caused irreversible damage and is usually too big to be removed without increasing that damage, especially if total extirpation is attempted. The purpose of this report is to show that it is possible to make a presumptive diagnosis of acoustic neuroma at a stage when the clinical features are almost entirely confined to disturbances of hearing and labyrinthine function, and that in such favourable circumstances the tumour can be removed without increasing the preoperative level of deafness, and without damaging the facial nerve or neighbouring structures. Case-records Case I.-Male, aged 50. In 1941 he consulted an otologist because of slight deafness in the left ear, and audiometry disclosed impairment for high tones. In 1945 he began to have attacks of giddiness lasting some minutes, during which his gait was unsteady ;there was no accompanying sense of In 1948 he first noticed rotation of self or surroundings. tmnitus in the left ear, but giddy spells were uncommon until
1950, when he began to experience true severe vertigo, which lasted hours at a time and was associated with nausea and a reeling gait. He could walk without unsteadiness between these attacks. In July of that year he was found to have multiple subcutaneous neurofibromata and a patch of pigmentation on one thigh. The nervous system was normal apart from the functions of the eighth nerve on the left. Otological Findings (C. S. Hallpike).-The tympanic membrane was normal. A whisper was heard at 3 feet (20 feet in the right ear). Weber’s test showed no reference to either ear. Air conduction was better than bone conduction in both ears, and absolute bone conduction was reduced on the left. Loudness balance tests showed incomplete recruitment on the left. There was no spontaneous nystagmus. The caloric response was reduced on the left side. Other Inve8tigations.-Radiographs of the internal auditory meatuses were normal, as were the pressure and constituents of the cerebrospinal fluid ;the protein content of the e.S.F. was 41) mg. per 100 ml. The Wassermann reaction (W.R.) in blood dnd c.s.F. was negative. Ventriculography showed a normal ventricular
system.
"
Operation.-Craniotomy was decided utological findings were consistent with
upon because (a) the a lesion of the eighth occasional accompani-
terve, and (b) neurofibromatosis is an of acoustic neuroma. At operation (W. McK.) a good of the lateral recess was obtained by elevating the left erebellar hemisphere after a unilateral occipital decompression, and a tumour 1 cm. in diameter was found on the posterior aspect of the eighth nerve. It was lightly adherent o the surface of the cerebellum but was easily removed. P,e,sult.-The patient made an uninterrupted recsovery and there was no postoperative facial weakness. For the first three seeks there was a moderate increase in the deafness, but :hereafter hearing returned to the preoperative level, and recruitment disappeared. The caloric response was unchanged, and there was no ataxia. ment tew
6850
vertigo,
and his deafness
aged 47. Early in 1950 he noticed the gradual slight deafness in the left ear. About a month later he complained of giddiness ; this was paroxysmal, with unsteadiness of gait but no sense of rotation. A persistent ache in the back of the neck kept him awake at nights, and for a fortnight preceding his admission in September, 1950, he had noticed intermittent twitching of the left side of the face. On examination he was found to have slight nystagmus when he looked to the left depression of the left corneal reflex despite normal corneal sensation, and slight deafness of the left ear. The nervous system was otherwise normal. Otological Findings (C. S. Hallpike).-Tympanic membrane normal. Whisper heard at 6 feet on left, at 20 feet on right. Case 2.-Male,
onset of tinnitus and
F. A. ELLIOTT ASSISTANT PHYSICIAN,
He has since remained free from has not increased.
Weber’s test not referred.
Air conduction better than bone conduction. No measurable loss of absolute bone conduction. Partial recruitment present. Caloric responses depressed on left. No nystagmus. Gait steady with eyes closed. Other Investigations.-Radiography showed marked funnelling of the left internal auditory meatus. Ventriculogram normal. C.S.F. : pressure normal ; protein content 20 mg. per 100 ml.; W.R. negative. Operation.-Craniotomy was decided upon because (a) the otological findings suggested a lesion of the eighth nerve rather than one of the internal ear, and (b) the left internal auditory meatus was enlarged. At operation (W. McK.) a unilateral exposure was made to- include the posterior lip of the foramen magnum, and it was then possible, by elevating the cerebellar hemisphere, to obtain a good view of the lower cranial nerves. A tumour, 1-5 cm. in diameter, was seen to be growing out of the internal meatus ; it was clear of the brain stem and fifth nerve. It was removed almost intact, and microscopical examination showed it to be a neuroma. Result.-After operation there was no facial weakness, and the level of deafness was unchanged. The partial recruitment, which had been present before, disappeared. There was, however, a subtotal abolition of the caloric response on the left and some unsteadiness of stance and gait, with slight nystagmus to the right. Full recovery was delayed for some months by an affective disorder : he felt " too weak to pour a cup of tea," walked with a stick, and protested his unfitness for work. There were no physical signs to sustain his plea and he looked the picture of health. This malaise, which had its roots in a domestic situation, eventually passed off and he has remained well since.
Case 3.-Female, aged 58. This woman had attended almost every department of the hospital in the past fifteen years. There was always an organic nucleus for her varied complaints, but her considerable sense of drama impaired the accuracy of her testimony, particularly as a sensory witness. However, it is recorded that in 1947 she first complained of left-sided deafness and tinnitus, and was found to have a slight degree of perceptive deafness. In 1949 she had several paroxysms of true vertigo. In 1952 she became aware of a persistent sense of unsteadiness which was aggravated by quick movements of her head, and at the same time she had a dull pain behind the left ear. She consulted Mr. Henry Sharp in January, 1953, and because of her unsteady gait he at once referred her for neurological examination. She was found to have moderate perceptive deafness in the left ear, a reduced corneal reflex on the same side, normal trigeminal sensation, and a slightly unsteady gait. There was no facial weakness, no nystagmus, and no incoordination of the limbs apart from her gait. The right Achilles reflex was absent, sole relic of poliomyelitis at the age of 37. At a subsequent examination, which took place after she had listened attentively to a clinical discussion on eighth-nerve tumours, she was found to have reduced sensibility to touch and pinprick over the whole of the left side of the face and the left pinna ; this was judged to be functional in origin. Otological Examination (C. S. Hallpike).-The tympanic membranes were normal. Whisper heard at 20 feet on the right, conversation voice at the left meatus. Air conduction was better than bone conduction on both sides. Absolute bone conduction was reduced on the left and there was incomplete recruitment on that side. The left caloric response was abolished. Other Investigations.-c.s.F. normal (protein 40 mg.) ; w.R. negative. Radiography of skull and internal auditory meatuses normal. Ventriculogram normal in all respects.
1190 Operation.-Craniotomy was decided upon because (a) gait unsteady between attacks of vertigo, (b) the otological findings were consistent with a lesion of the eighth nerve, and (c) the left corneal reflex was diminished. An additional point,
tosis, which afforded an early clue in
case 1, is uncommon, but the association with acoustic neuroma--especially bilateral neuromata-is well known. Radiological examination may reveal enlargement of the internal auditory meatus on the deaf side, as in case 2, but a normal meatus does not exclude a neuroma. Although in all our cases the c.s.F. was normal, it may
was
which may have been relevant but which was not discovered until after operation, was that she had had some perianal tags removed in 1949, and one of these had been proved to be a pedunculated neurofibroma. At operation (W. McK.) a decompression of the left half of the posterior fossa permitted the left cerebellar hemisphere to be elevated sufficiently to give a good view of the eighth nerve. On it there was a nodular tumour about 1 cm. in diameter, with its lateral pole just inside the internal auditory meatus and its medial edge just touching the pons. The eighth nerve was depressed by the nodule, and the facial nerve ran round its anterosuperior border. Complete removal presented no difficulties. The tumour was proved to be a neurolemmoma. Result.-For the first six weeks after operation there was slight weakness of the upper face, but this passed off. The corneal reflex remained depressed. There was no trigeminal sensory loss, but for almost a year she had a dull ache over the left side of the face. Hearing was improved by the operation but tinnitus persisted. Gait gradually returned to normal, but she continued to feel off-balance if she moved her head quickly. Both this symptom and the dull pain in her face disappeared suddenly : while lifting a heavy weight " something went pop inside my head, and the pain went." She has remained well since.
contain
excess
Clearly, routine methods of
protein.
investigation cannot contribute much to early diagnosis, and we relied more on caloric tests and audiometry. The results of these tests, carried out by Mr. C. S. Hallpike, encouraged us to explore cases 1 and 3 earlier than was justified on the clinical findings alone ; in case 2 he found evidence of an enlarged meatus
eighth
nerve
lesion
as
well, but the
itself have justified surgical intervention. The caloric responses are usually either depressed or lost on the affected side in acoustic neuroma, but since this is also true of many cases of labyrinthine disease the test cannot distinguish between them. A normal response, however, is evidence against the presence of a neuroma. (Loss of caloric responses does not necessarily mean that the labyrinth or the vestibular nerve is dead"; it merely implies that this specialised stimulus is no longer seen
on
radiography would by
"
effective.) Tuning-fork tests usually enable conduction deafness to be distinguished from perception or nerve " deafness.
Discussion
"
There is ample evidence that something like 75% of all of acoustic neuroma have, as their first symptom, either deafness or tinnitus or vertigo, or a sense of disequilibrium short of vertigo (Cushing 1917, Olsen and Horrax 1944, Revilla 1947, Edwards and Paterson 1951). This figure would probably be higher were it not that many middle-aged people accept a moderate degree of deafness as something appropriate to their age, and so do not seek advice until more dramatic symptoms superThe result is that most patients with acoustic vene. neuroma remain under the care of otologists and physicians during the period when surgery offers the best chance of complete recovery, and they seldom reach the neurosurgeon until the tumour has grown large enough to involve nearby structures or cause a rise of intracranial pressure. The conventional textbook description of an acoustic neuroma is, as a rule, an account of a comparatively large mass which can constitute a formidable surgical hazard. We believe that this situation can be improved if patients with aural symptoms are thoroughly examined, in particular by the special methods of otological investigation described below. This view is based on the cases reported here and on a comparable case reported by Kristensen (1953). It must be admitted, however, that the number of acoustic nerve lesions diagnosed by these arduous methods will be small, since the great majority of patients with these symptoms will be found to have Meniere’s disease or some other peripheral aural lesion (Cawthorne 1954). Moreover, otological tests cannot do more than point to the eighth nerve as the probable site of the lesion ; they cannot by themselves provethat the lesion is a neuroma, but they can strongly support the diagnosis when taken in conjunction with the clinical findings. The clinical history is often suggestive. Deafness and tinnitus usually precede vertigo, but this sequence is also found in Meniere’s disease (Cawthorne 1954). Twitching of the face, and unsteadiness of gait without actual vertigo, are significant symptoms. Paraesthesise of the face and early morning headaches are usually later in cases
symptoms
developing, but sometimes they are the first for which the patient seeks advice. The physical signs which are important for early diagnosis are quickly and easily identified : perceptive deafness, reduction of the corneal reflex, facial weakness, and unsteadiness of gait and stance. Cerebellar ataxia and trigeminal sensory loss are later developments. The presence of neurofibroma-
.
In most cases of acoustic neuroma, air conduction is better than bone conduction if there is any hearing left, but occasionally Rinne’s test is negative, and the deafness is then often attributed incorrectly to disease of the middle ear. (The reason for the anomaly has been investi. gated by Dix and Hallpike 1950.) Mistakes can be avoided if Schwabach’s test is carried out as well, because a reduction of absolute bone conduction indicates perceptive deafness whatever the result of Rinne’s test. By these simple procedures it is easy to establish that the impairment of hearing is due to a lesion either of the cochlea or of the eighth nerve ; but they cannot distinguish between the two. For this, the loudness balance test is needed (Fowler 1936, Dix, Hallpike, and Hood 1949). It has been shown that in cochlear disease the impairment of hearing present at threshold diminishes as the intensity of the stimulus is increased, until a point is reached when the sound is heard equally well by both ears, or may even appear louder on the affected side. This phenomenon, known as recruitment (and over-recruitment) does. not occur in eighth-nerve lesions, although in acoustic neuromata partial recruitment may occur. It was present in the three cases reported here, but disappeared after the tumours were removed, and it would seem possible that the tumour interferes with the internal auditory artery and its vense comites, and so produces temporary and reversible changes in the cochlea. Whatever the explanation, there is little doubt that the presence of full recruitment in a case of perceptive deafness argues against the presence of an acoustic neuroma. The physical signs in our cases are of interest. The impairment of the corneal reflex in cases 2 and 3 cannot have been due to interference with the trigeminal sensory root, which the tumours were too small to reach, so it was probably caused by involvement of the facial nerve-an explanation which gains support from the observation that in case 2 there was twitching of the face before operation. Clearly, in acoustic neuromata depression of the corneal reflex is not necessarily proof of trigeminal involvement, although this doubtless occurs in the larger growths. The pain and deep tenderness in the face after operation in case 3 cannot be explained conclusively, but the sudden disappearance of these symptoms, as well as of her giddiness, after " something went pop " in her head suggests that a postoperative arachnoidal cyst in the lateral recess was responsible. Whether the pain and tenderness were due to irritation of the
1191
trigeminal root,
or
of the sensory fibres of the facial
nerve, remains in doubt.
The unsteadiness of
gait,
which in
cases
2 and
3
occurred apart from attacks of vertigo, cannot have resulted from pressure on the cerebellum or pons, since the tumours were too small to interfere with these structures or with their blood-supply. Presumably it was due to the effect of the tumour on the vestibular component of the eighth nerve, and it was in fact very similar to what is seen for a few days or weeks after therapeutic section of the vestibular nerve for Menieres disease. It is reasonable to conclude that this labyrinthine factor may also contribute to the disequilibrium found in patients with the more advanced acoustic tumours, which would explain why the incoordination observed in those patients is not always wholly consistent with a unilateral cerebellar disturbance. These inconsistencies were well described by Edwards and Paterson. In particular, some patients show cerebellar incoördination of the limbs on the side of the tumour, yet deviate to the opposite side when walking-a phenomenon which may be explained by the combined effect of cerebellar involvement on one side and unopposed action of the contralateral labyrinth. Moreover, while unsteadiness of stance and gait without other evidence of cerebellar incoordination can be due to damage to the midline flocculonodular lobe of the cerebellum, this is clearly not the explanation of such unsteadiness in patients with the smaller tumours. Finally, the fact that stance and gait bscame normal in cases 2 and 3 some weeks after operation upholds this hypothesis of labyrinthine imbalance, for it is well known that patients can in time adapt surprisingly well to unilateral loss of labyrinthine function. Although most cases of acoustic neuroma have nystagmus by the time they come to operation, its type and degree vary greatly from case to case, and even from day to day in the same case. Fortunately the tumour As we have can be localised by more reliable signs. noted, none of our cases had nystagmus before operation, but for some weeks after operation all presented a vestibular-type nystagmus to the right (i.e., contralateral to the tumour) presumably produced by mild surgical damage to the vestibular nerve. Similarly, involvement of the vestibular nerve may well be the explanation of the nystagmus seen preoperatively in patients with rapidly growing tumours. That is to say, nystagmus may be both cerebellar and vestibular in origin in large tumours, the variation from case to case depending on the extent to which each factor operates. In conclusion : the chances of a satisfactory outcome from operation on cases of acoustic neuroma are greatly increased by early diagnosis-i.e., when symptoms and signs are confined to disturbances of function of the eighth nerve. Usually the patient first seeks advice from an otologist, and unless the tumour has grown large enough to cause significant symptoms and signs the clinical picture at this stage may not greatly differ from that seen in the more common diseases of the cochlea. A complete neurological examination, including caloric and audiometric testing, of all patients with perception deafness is hardly possible ; but a careful history, and an examination restricted to gait, stance, and the fifth, seventh, and eighth cranial nerves, will usually suffice to pick out the cases which require full-scale otological
in toto without increasing the preoperative level of deafness and without causing facial paralysis. 3. The diagnostic value of otological tests, especially the loudness balance test, is emphasised. 4. Evidence is presented to show that depression of the corneal reflex in early cases is due to interference with the motor part of the reflex arc in the facial nerve, and does not necessarily imply damage to the trigeminal sensory root. 5. It is
suggested that damage to the vestibular comof the eighth nerve can cause unsteadiness of ponent stance and gait, and that these symptoms do not necessarily indicate interference with the cerebellum, though they may complicate the cerebellar ataxia seen in more advanced cases. 6. The possibility of early diagnosis, at a stage when symptoms are confined to disturbances of eighth-nerve function, is emphasised. REFERENCES
Cawthorne, T. (1954) Proc. R. Soc. Med. 47, 663. Cushing, H. (1917) Tumours of the Nervus Acusticus and Syndrome of the Cerebello-pontile Angle. Philadelphia. Dix, M. R., Hallpike, C. S. (1950) Proc. R. Soc. Med. 43, 291. Hood, J. D. (1949) Ibid, 42, 527. Edwards, C. H., Paterson. J. H. (1951) Brain, 74, 144. E. P. (1936) Arch. Otolaryng., Chicago, 24, 731. Fowler, Horrax, G., Poppen, J. L. (1939) Ann. Surg. 110, 513. Kristensen, H. K. (1953) Acta Psychiat., Kbh. 28, 287. Olivecrona, H. (1940) J. Neurol. Psychiat. 3, 1941. Olsen, A., Horrax, G. (1944) J. Neurosurg. 1 371. Revilla, G. (1947) Bull. Johns Hopk. Hosp. 80, 254. —
—
THE USE OF CONTINUOUS INTRAVENOUS OXYTOCIN IN OBSTETRICS J. M. HOLMES Lond., M.R.C.O.G.
M.D. OBSTETRIC
REGISTRAR, GLY’S HOSPITAL,
THE oxytocic action of posterior pituitary extract was first observed by Dale in 1906, but the oxytocic factor was not isolated until 1928 (Kamm et al.). Meanwhile Bell (1909) had advocated its use in clinical obstetrics, and Hofbauer (1911) had recommended it for uterine inertia. During the last forty years it has been applied in many different obstetrical conditions and circumstances and its use has been followed often by foetal death and occasionally by uterine rupture. As an agent for inducing labour and for stimulating the inert uterus, oxytocin has been severely criticised, and many believe that it has no place in practical midwifery. I have therefore tried to assess the safety of iiitravenous oxytocin given in high dilutions, which probably approximate to physiological levels, and to discover the conditions which must obtain before administering oxytocin and the contra-indications to oxytocin therapy.
Preliminary Investigation The response of the human uterus to oxytocin varies not only with the dose but also with the irritability of the uterus. Using an external
Lorand
1. The
labour
high, especially
are
(Holmes
It was found that this uterine response
1952).
·
I-Tetanic uterine response to intra. muscular oxytocin in primigravida after death of foetus at 37 weeks from unknown
Fig.
postoperative mortality and morbidity
patients with acoustic neuromata
tocograph,
the uterine response to intramuscular oxytocin 2 units was observed late in pregnancy and.early
investigation.
Summary
LONDON
in
disappointingly
in view of the benign character and relative accessibility of most of these tumours. 2. Three caes are described in which diagnosis was made at a stage when only the seventh and eighth nerves were involved by the growth. Thetumours were removed
may be maximal, with complete uterCastor oil, hot bath, and enema ine tetanus (fig. 1), or produced painless contractions only. it may be less comOxytocin 2 units produced within 2 with irregular minutes uterine tetanus which lasted contractions and 15 minutes. cause.
plete,
ORIGINAL ARTICLES ACOUSTIC NEUROMA EARLY DIAGNOSIS F.R.C.P. CHARINC
CROSS
HOSPITAL, LONDON
WYLIE MCKISSOCK O.B.E., M.S. Lond., F.R.C.S. SURGEON, ST. GEORGE’S HOSPITAL, LONDON
ALTHOUGH acoustic neuromata are surgically accessible and usually benign, the operative mortality in the best hands is not less than 10% (Olivecrona 1940, Horrax and poppen 1939), and recurrences are not uncommon. Moreover, the postoperative morbidity is considerable :
the operation may be followed by facial paralysis, unsteadiness of gait, visual impairment from secondary optic atrophy, and a general malaise which interferes with work and with the enjoyment of life. The main reason for this unsatisfactory state of affairs is that by the time a neuroma has grown large enough to fulfil present diagnostic criteria it has already caused irreversible damage and is usually too big to be removed without increasing that damage, especially if total extirpation is attempted. The purpose of this report is to show that it is possible to make a presumptive diagnosis of acoustic neuroma at a stage when the clinical features are almost entirely confined to disturbances of hearing and labyrinthine function, and that in such favourable circumstances the tumour can be removed without increasing the preoperative level of deafness, and without damaging the facial nerve or neighbouring structures. Case-records Case I.-Male, aged 50. In 1941 he consulted an otologist because of slight deafness in the left ear, and audiometry disclosed impairment for high tones. In 1945 he began to have attacks of giddiness lasting some minutes, during which his gait was unsteady ;there was no accompanying sense of In 1948 he first noticed rotation of self or surroundings. tmnitus in the left ear, but giddy spells were uncommon until
1950, when he began to experience true severe vertigo, which lasted hours at a time and was associated with nausea and a reeling gait. He could walk without unsteadiness between these attacks. In July of that year he was found to have multiple subcutaneous neurofibromata and a patch of pigmentation on one thigh. The nervous system was normal apart from the functions of the eighth nerve on the left. Otological Findings (C. S. Hallpike).-The tympanic membrane was normal. A whisper was heard at 3 feet (20 feet in the right ear). Weber’s test showed no reference to either ear. Air conduction was better than bone conduction in both ears, and absolute bone conduction was reduced on the left. Loudness balance tests showed incomplete recruitment on the left. There was no spontaneous nystagmus. The caloric response was reduced on the left side. Other Inve8tigations.-Radiographs of the internal auditory meatuses were normal, as were the pressure and constituents of the cerebrospinal fluid ;the protein content of the e.S.F. was 41) mg. per 100 ml. The Wassermann reaction (W.R.) in blood dnd c.s.F. was negative. Ventriculography showed a normal ventricular
system.
"
Operation.-Craniotomy was decided utological findings were consistent with
upon because (a) the a lesion of the eighth occasional accompani-
terve, and (b) neurofibromatosis is an of acoustic neuroma. At operation (W. McK.) a good of the lateral recess was obtained by elevating the left erebellar hemisphere after a unilateral occipital decompression, and a tumour 1 cm. in diameter was found on the posterior aspect of the eighth nerve. It was lightly adherent o the surface of the cerebellum but was easily removed. P,e,sult.-The patient made an uninterrupted recsovery and there was no postoperative facial weakness. For the first three seeks there was a moderate increase in the deafness, but :hereafter hearing returned to the preoperative level, and recruitment disappeared. The caloric response was unchanged, and there was no ataxia. ment tew
6850
vertigo,
and his deafness
aged 47. Early in 1950 he noticed the gradual slight deafness in the left ear. About a month later he complained of giddiness ; this was paroxysmal, with unsteadiness of gait but no sense of rotation. A persistent ache in the back of the neck kept him awake at nights, and for a fortnight preceding his admission in September, 1950, he had noticed intermittent twitching of the left side of the face. On examination he was found to have slight nystagmus when he looked to the left depression of the left corneal reflex despite normal corneal sensation, and slight deafness of the left ear. The nervous system was otherwise normal. Otological Findings (C. S. Hallpike).-Tympanic membrane normal. Whisper heard at 6 feet on left, at 20 feet on right. Case 2.-Male,
onset of tinnitus and
F. A. ELLIOTT ASSISTANT PHYSICIAN,
He has since remained free from has not increased.
Weber’s test not referred.
Air conduction better than bone conduction. No measurable loss of absolute bone conduction. Partial recruitment present. Caloric responses depressed on left. No nystagmus. Gait steady with eyes closed. Other Investigations.-Radiography showed marked funnelling of the left internal auditory meatus. Ventriculogram normal. C.S.F. : pressure normal ; protein content 20 mg. per 100 ml.; W.R. negative. Operation.-Craniotomy was decided upon because (a) the otological findings suggested a lesion of the eighth nerve rather than one of the internal ear, and (b) the left internal auditory meatus was enlarged. At operation (W. McK.) a unilateral exposure was made to- include the posterior lip of the foramen magnum, and it was then possible, by elevating the cerebellar hemisphere, to obtain a good view of the lower cranial nerves. A tumour, 1-5 cm. in diameter, was seen to be growing out of the internal meatus ; it was clear of the brain stem and fifth nerve. It was removed almost intact, and microscopical examination showed it to be a neuroma. Result.-After operation there was no facial weakness, and the level of deafness was unchanged. The partial recruitment, which had been present before, disappeared. There was, however, a subtotal abolition of the caloric response on the left and some unsteadiness of stance and gait, with slight nystagmus to the right. Full recovery was delayed for some months by an affective disorder : he felt " too weak to pour a cup of tea," walked with a stick, and protested his unfitness for work. There were no physical signs to sustain his plea and he looked the picture of health. This malaise, which had its roots in a domestic situation, eventually passed off and he has remained well since.
Case 3.-Female, aged 58. This woman had attended almost every department of the hospital in the past fifteen years. There was always an organic nucleus for her varied complaints, but her considerable sense of drama impaired the accuracy of her testimony, particularly as a sensory witness. However, it is recorded that in 1947 she first complained of left-sided deafness and tinnitus, and was found to have a slight degree of perceptive deafness. In 1949 she had several paroxysms of true vertigo. In 1952 she became aware of a persistent sense of unsteadiness which was aggravated by quick movements of her head, and at the same time she had a dull pain behind the left ear. She consulted Mr. Henry Sharp in January, 1953, and because of her unsteady gait he at once referred her for neurological examination. She was found to have moderate perceptive deafness in the left ear, a reduced corneal reflex on the same side, normal trigeminal sensation, and a slightly unsteady gait. There was no facial weakness, no nystagmus, and no incoordination of the limbs apart from her gait. The right Achilles reflex was absent, sole relic of poliomyelitis at the age of 37. At a subsequent examination, which took place after she had listened attentively to a clinical discussion on eighth-nerve tumours, she was found to have reduced sensibility to touch and pinprick over the whole of the left side of the face and the left pinna ; this was judged to be functional in origin. Otological Examination (C. S. Hallpike).-The tympanic membranes were normal. Whisper heard at 20 feet on the right, conversation voice at the left meatus. Air conduction was better than bone conduction on both sides. Absolute bone conduction was reduced on the left and there was incomplete recruitment on that side. The left caloric response was abolished. Other Investigations.-c.s.F. normal (protein 40 mg.) ; w.R. negative. Radiography of skull and internal auditory meatuses normal. Ventriculogram normal in all respects.
1190 Operation.-Craniotomy was decided upon because (a) gait unsteady between attacks of vertigo, (b) the otological findings were consistent with a lesion of the eighth nerve, and (c) the left corneal reflex was diminished. An additional point,
tosis, which afforded an early clue in
case 1, is uncommon, but the association with acoustic neuroma--especially bilateral neuromata-is well known. Radiological examination may reveal enlargement of the internal auditory meatus on the deaf side, as in case 2, but a normal meatus does not exclude a neuroma. Although in all our cases the c.s.F. was normal, it may
was
which may have been relevant but which was not discovered until after operation, was that she had had some perianal tags removed in 1949, and one of these had been proved to be a pedunculated neurofibroma. At operation (W. McK.) a decompression of the left half of the posterior fossa permitted the left cerebellar hemisphere to be elevated sufficiently to give a good view of the eighth nerve. On it there was a nodular tumour about 1 cm. in diameter, with its lateral pole just inside the internal auditory meatus and its medial edge just touching the pons. The eighth nerve was depressed by the nodule, and the facial nerve ran round its anterosuperior border. Complete removal presented no difficulties. The tumour was proved to be a neurolemmoma. Result.-For the first six weeks after operation there was slight weakness of the upper face, but this passed off. The corneal reflex remained depressed. There was no trigeminal sensory loss, but for almost a year she had a dull ache over the left side of the face. Hearing was improved by the operation but tinnitus persisted. Gait gradually returned to normal, but she continued to feel off-balance if she moved her head quickly. Both this symptom and the dull pain in her face disappeared suddenly : while lifting a heavy weight " something went pop inside my head, and the pain went." She has remained well since.
contain
excess
Clearly, routine methods of
protein.
investigation cannot contribute much to early diagnosis, and we relied more on caloric tests and audiometry. The results of these tests, carried out by Mr. C. S. Hallpike, encouraged us to explore cases 1 and 3 earlier than was justified on the clinical findings alone ; in case 2 he found evidence of an enlarged meatus
eighth
nerve
lesion
as
well, but the
itself have justified surgical intervention. The caloric responses are usually either depressed or lost on the affected side in acoustic neuroma, but since this is also true of many cases of labyrinthine disease the test cannot distinguish between them. A normal response, however, is evidence against the presence of a neuroma. (Loss of caloric responses does not necessarily mean that the labyrinth or the vestibular nerve is dead"; it merely implies that this specialised stimulus is no longer seen
on
radiography would by
"
effective.) Tuning-fork tests usually enable conduction deafness to be distinguished from perception or nerve " deafness.
Discussion
"
There is ample evidence that something like 75% of all of acoustic neuroma have, as their first symptom, either deafness or tinnitus or vertigo, or a sense of disequilibrium short of vertigo (Cushing 1917, Olsen and Horrax 1944, Revilla 1947, Edwards and Paterson 1951). This figure would probably be higher were it not that many middle-aged people accept a moderate degree of deafness as something appropriate to their age, and so do not seek advice until more dramatic symptoms superThe result is that most patients with acoustic vene. neuroma remain under the care of otologists and physicians during the period when surgery offers the best chance of complete recovery, and they seldom reach the neurosurgeon until the tumour has grown large enough to involve nearby structures or cause a rise of intracranial pressure. The conventional textbook description of an acoustic neuroma is, as a rule, an account of a comparatively large mass which can constitute a formidable surgical hazard. We believe that this situation can be improved if patients with aural symptoms are thoroughly examined, in particular by the special methods of otological investigation described below. This view is based on the cases reported here and on a comparable case reported by Kristensen (1953). It must be admitted, however, that the number of acoustic nerve lesions diagnosed by these arduous methods will be small, since the great majority of patients with these symptoms will be found to have Meniere’s disease or some other peripheral aural lesion (Cawthorne 1954). Moreover, otological tests cannot do more than point to the eighth nerve as the probable site of the lesion ; they cannot by themselves provethat the lesion is a neuroma, but they can strongly support the diagnosis when taken in conjunction with the clinical findings. The clinical history is often suggestive. Deafness and tinnitus usually precede vertigo, but this sequence is also found in Meniere’s disease (Cawthorne 1954). Twitching of the face, and unsteadiness of gait without actual vertigo, are significant symptoms. Paraesthesise of the face and early morning headaches are usually later in cases
symptoms
developing, but sometimes they are the first for which the patient seeks advice. The physical signs which are important for early diagnosis are quickly and easily identified : perceptive deafness, reduction of the corneal reflex, facial weakness, and unsteadiness of gait and stance. Cerebellar ataxia and trigeminal sensory loss are later developments. The presence of neurofibroma-
.
In most cases of acoustic neuroma, air conduction is better than bone conduction if there is any hearing left, but occasionally Rinne’s test is negative, and the deafness is then often attributed incorrectly to disease of the middle ear. (The reason for the anomaly has been investi. gated by Dix and Hallpike 1950.) Mistakes can be avoided if Schwabach’s test is carried out as well, because a reduction of absolute bone conduction indicates perceptive deafness whatever the result of Rinne’s test. By these simple procedures it is easy to establish that the impairment of hearing is due to a lesion either of the cochlea or of the eighth nerve ; but they cannot distinguish between the two. For this, the loudness balance test is needed (Fowler 1936, Dix, Hallpike, and Hood 1949). It has been shown that in cochlear disease the impairment of hearing present at threshold diminishes as the intensity of the stimulus is increased, until a point is reached when the sound is heard equally well by both ears, or may even appear louder on the affected side. This phenomenon, known as recruitment (and over-recruitment) does. not occur in eighth-nerve lesions, although in acoustic neuromata partial recruitment may occur. It was present in the three cases reported here, but disappeared after the tumours were removed, and it would seem possible that the tumour interferes with the internal auditory artery and its vense comites, and so produces temporary and reversible changes in the cochlea. Whatever the explanation, there is little doubt that the presence of full recruitment in a case of perceptive deafness argues against the presence of an acoustic neuroma. The physical signs in our cases are of interest. The impairment of the corneal reflex in cases 2 and 3 cannot have been due to interference with the trigeminal sensory root, which the tumours were too small to reach, so it was probably caused by involvement of the facial nerve-an explanation which gains support from the observation that in case 2 there was twitching of the face before operation. Clearly, in acoustic neuromata depression of the corneal reflex is not necessarily proof of trigeminal involvement, although this doubtless occurs in the larger growths. The pain and deep tenderness in the face after operation in case 3 cannot be explained conclusively, but the sudden disappearance of these symptoms, as well as of her giddiness, after " something went pop " in her head suggests that a postoperative arachnoidal cyst in the lateral recess was responsible. Whether the pain and tenderness were due to irritation of the
1191
trigeminal root,
or
of the sensory fibres of the facial
nerve, remains in doubt.
The unsteadiness of
gait,
which in
cases
2 and
3
occurred apart from attacks of vertigo, cannot have resulted from pressure on the cerebellum or pons, since the tumours were too small to interfere with these structures or with their blood-supply. Presumably it was due to the effect of the tumour on the vestibular component of the eighth nerve, and it was in fact very similar to what is seen for a few days or weeks after therapeutic section of the vestibular nerve for Menieres disease. It is reasonable to conclude that this labyrinthine factor may also contribute to the disequilibrium found in patients with the more advanced acoustic tumours, which would explain why the incoordination observed in those patients is not always wholly consistent with a unilateral cerebellar disturbance. These inconsistencies were well described by Edwards and Paterson. In particular, some patients show cerebellar incoördination of the limbs on the side of the tumour, yet deviate to the opposite side when walking-a phenomenon which may be explained by the combined effect of cerebellar involvement on one side and unopposed action of the contralateral labyrinth. Moreover, while unsteadiness of stance and gait without other evidence of cerebellar incoordination can be due to damage to the midline flocculonodular lobe of the cerebellum, this is clearly not the explanation of such unsteadiness in patients with the smaller tumours. Finally, the fact that stance and gait bscame normal in cases 2 and 3 some weeks after operation upholds this hypothesis of labyrinthine imbalance, for it is well known that patients can in time adapt surprisingly well to unilateral loss of labyrinthine function. Although most cases of acoustic neuroma have nystagmus by the time they come to operation, its type and degree vary greatly from case to case, and even from day to day in the same case. Fortunately the tumour As we have can be localised by more reliable signs. noted, none of our cases had nystagmus before operation, but for some weeks after operation all presented a vestibular-type nystagmus to the right (i.e., contralateral to the tumour) presumably produced by mild surgical damage to the vestibular nerve. Similarly, involvement of the vestibular nerve may well be the explanation of the nystagmus seen preoperatively in patients with rapidly growing tumours. That is to say, nystagmus may be both cerebellar and vestibular in origin in large tumours, the variation from case to case depending on the extent to which each factor operates. In conclusion : the chances of a satisfactory outcome from operation on cases of acoustic neuroma are greatly increased by early diagnosis-i.e., when symptoms and signs are confined to disturbances of function of the eighth nerve. Usually the patient first seeks advice from an otologist, and unless the tumour has grown large enough to cause significant symptoms and signs the clinical picture at this stage may not greatly differ from that seen in the more common diseases of the cochlea. A complete neurological examination, including caloric and audiometric testing, of all patients with perception deafness is hardly possible ; but a careful history, and an examination restricted to gait, stance, and the fifth, seventh, and eighth cranial nerves, will usually suffice to pick out the cases which require full-scale otological
in toto without increasing the preoperative level of deafness and without causing facial paralysis. 3. The diagnostic value of otological tests, especially the loudness balance test, is emphasised. 4. Evidence is presented to show that depression of the corneal reflex in early cases is due to interference with the motor part of the reflex arc in the facial nerve, and does not necessarily imply damage to the trigeminal sensory root. 5. It is
suggested that damage to the vestibular comof the eighth nerve can cause unsteadiness of ponent stance and gait, and that these symptoms do not necessarily indicate interference with the cerebellum, though they may complicate the cerebellar ataxia seen in more advanced cases. 6. The possibility of early diagnosis, at a stage when symptoms are confined to disturbances of eighth-nerve function, is emphasised. REFERENCES
Cawthorne, T. (1954) Proc. R. Soc. Med. 47, 663. Cushing, H. (1917) Tumours of the Nervus Acusticus and Syndrome of the Cerebello-pontile Angle. Philadelphia. Dix, M. R., Hallpike, C. S. (1950) Proc. R. Soc. Med. 43, 291. Hood, J. D. (1949) Ibid, 42, 527. Edwards, C. H., Paterson. J. H. (1951) Brain, 74, 144. E. P. (1936) Arch. Otolaryng., Chicago, 24, 731. Fowler, Horrax, G., Poppen, J. L. (1939) Ann. Surg. 110, 513. Kristensen, H. K. (1953) Acta Psychiat., Kbh. 28, 287. Olivecrona, H. (1940) J. Neurol. Psychiat. 3, 1941. Olsen, A., Horrax, G. (1944) J. Neurosurg. 1 371. Revilla, G. (1947) Bull. Johns Hopk. Hosp. 80, 254. —
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THE USE OF CONTINUOUS INTRAVENOUS OXYTOCIN IN OBSTETRICS J. M. HOLMES Lond., M.R.C.O.G.
M.D. OBSTETRIC
REGISTRAR, GLY’S HOSPITAL,
THE oxytocic action of posterior pituitary extract was first observed by Dale in 1906, but the oxytocic factor was not isolated until 1928 (Kamm et al.). Meanwhile Bell (1909) had advocated its use in clinical obstetrics, and Hofbauer (1911) had recommended it for uterine inertia. During the last forty years it has been applied in many different obstetrical conditions and circumstances and its use has been followed often by foetal death and occasionally by uterine rupture. As an agent for inducing labour and for stimulating the inert uterus, oxytocin has been severely criticised, and many believe that it has no place in practical midwifery. I have therefore tried to assess the safety of iiitravenous oxytocin given in high dilutions, which probably approximate to physiological levels, and to discover the conditions which must obtain before administering oxytocin and the contra-indications to oxytocin therapy.
Preliminary Investigation The response of the human uterus to oxytocin varies not only with the dose but also with the irritability of the uterus. Using an external
Lorand
1. The
labour
high, especially
are
(Holmes
It was found that this uterine response
1952).
·
I-Tetanic uterine response to intra. muscular oxytocin in primigravida after death of foetus at 37 weeks from unknown
Fig.
postoperative mortality and morbidity
patients with acoustic neuromata
tocograph,
the uterine response to intramuscular oxytocin 2 units was observed late in pregnancy and.early
investigation.
Summary
LONDON
in
disappointingly
in view of the benign character and relative accessibility of most of these tumours. 2. Three caes are described in which diagnosis was made at a stage when only the seventh and eighth nerves were involved by the growth. Thetumours were removed
may be maximal, with complete uterCastor oil, hot bath, and enema ine tetanus (fig. 1), or produced painless contractions only. it may be less comOxytocin 2 units produced within 2 with irregular minutes uterine tetanus which lasted contractions and 15 minutes. cause.
plete,