Anatomic motor point localization for partial quadriceps block in spasticity

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Anatomic Motor Point Localization Block in Spasticity

for Partial Quadriceps

Thierry Albert, MD, Alain Yelnik, MD, Florence Colle, MD, Isabelle Bonan, MD, Jean Pierre Lmsau, MD ABSTRACT. Albert T, Yelnik A, Colle F, Bonan I, Lassau Jl? Anatomic motor point localization for partial quadriceps block in spasticity. Arch Phys Med Rehabil2000;8 I:2857. Objective: To identify the location of the vastus intermedius nerve and its motor point (point M) and to precisely identify its coordinates in relation to anatomic surface landmarks. Design: Descriptive study. Setting: Anatomy institute of a university school of medicine. Participants: Twenty-nine adult cadaver limbs immobilized in anatomic position. Intervention: Anatomic dissection to identify point M. Anatomic surface landmarks were point F, the issuing point of femoral nerve under the inguinal ligament; point R, the middle of superior edge of the patella; segment FR, which corresponds to thigh length; point M’, point M orthogonal projection on segment FR. Mean Outcome Measure: Absolute vertical coordinate, distance FM, relative vertical coordinate compared to the thigh length, FM’IFR ratio; absolute horizontal coordinate, distance MM’. Results: The absolute vertical coordinate was 11.7 2 2cm. The relativeverticalcoordinatewas at .29 + .04 of thigh length.The horizontal coordinate was at 2 5 Scm lateral to the FR line. Conclusion: Point M can be defined with relative precision by two coordinates. Application and clinical interest of nerve blocking using these coordinates in quadriceps spasticity should be studied. Key Words: Motor point; Quadriceps; Spasticity; Nerve block. 0 2000 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

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UADRICEPS SPASTICITY can limit the hemiplegic patient’s ability to walk by preventing sufficient knee flexIon during the swing phase of gait. A dynamic electromyographic study of spastic stiff-legged gait found that the majority of patients (19 of 23.83%) had inappropriate activity in at least one head of the quadriceps vasti during preswing or initial swing of walking; specifically, the vastus intermedius muscle was more commonly active during either or both of these From the Service de R&education et de R&adaptation Fonctionnelles, HBpital Femand Widal (Drs. Alben. Yelnik. Colle, Bonan); and Ihe lnsritut d’anatomie de Paris. faculte de medecine des Saint Peres (Drs. Alberf Lassau). Paris. Submitted for publication January 12. 1999. Accepted in revised fom July 27. 1999. Preliminary data were presented at the Soci&Z franqaise de Rttducation fonctionnelle. de r&daptation. et de mddecine physique (SOFMERR) annual assembly. October 16-18. 1997. Strasbourg. France. No commercial party having a direct financial interesI in the results of the research supporting Ihis article has or will confer a benefit upon Ihe authors or upon any organization with which Ihe authors are associated. Reprint requesIs IO Thierry Albert. MD. Service de Reeducation e1 de Readaptation Fonctionnelles. Hbpiral Femand Widal. 200 rue du Faubourg Saint Denis, 75475 Cedex IO. Paris. France. 0 2000 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation 0003-9993/00/8103-5407$3.00/O

phases than the vastus medialis or the muscle vastus lateralis.’ No efficient treatment of quadriceps spasticity by a block technique has been reported. 2.3A possible explanation is that a femoral nerve block would paralyze all of the quadriceps muscles and increase gait incapacity. We suggest it would be possible to selectively block just one branch of the quadriceps nerve to avoid a total paralysis of the muscle.The quadricepsnerve is the principal branch of the femoral nerve; it divides into four branchesfor each head of the quadriceps. We have chosenthe vastusintermediusmusclebecauseit appearsto be the most overactive in quadriceps spasticity,l possibly because of its higher proportion of tonic fibers (similar to the soleus contribution to triceps surae spasticity). Classical anatomic literature describes either one or three vastus intermedius nerves: the principal nerve issuesfrom the quadriceps nerve, which enters high in the muscle. According to some authors, two other nerves issue from the vastus lateralis nerve and vastus medialis nerve, both of them entering lower in the muscle.3-6These descriptions are insufficient to identify the exact nerve course and precisely determine the entry point into the muscle. The objective of this anatomic study was to define the coordinates of the vastus intermedius nerve motor point on the skin. These coordinates were established from easily palpable anatomic landmarks. MATERIALS AND METHODS An anatomic dissection study of the inferior limb in adult cadavers was undertaken. There was no selection of cadavers and no excluded limb. Each subject was placed in a supine position with the limb immobilized in the anatomic position until completion of all measurements. The anterior femoral region and the femoral trigon were dissected. The femoral nerve, the quadriceps nerve and its branches, and the vastus intermedius nerve motor point were exposed. The motor point was defined as the location where the nerve entered into the muscle and was designated point M. This motor point can be defined by two coordinates, a vertical coordinate related to the height of the thigh and a horizontal coordinate related to its width. Coordinate measurements were made of different anatomic landmarks. These are easily found and reproducible by an anatomic examination. Anatomical landmarks were defined (fig 1) as: 1. Point F: Point of emergence of the femoral nerve from under the femoral arcade. On a living subject, it is located at one finger-width lateral to the femoral artery, which is identified by the femoral pulse.’ 2. Point R: middle of the superior edge of the patella. 3. Distance FR: Segment joining F and R, which indicates thigh length. 4. Point M’: orthogonal projection of the point M on segment FR. The distance between F and M’ (FM’) is the absolute vertical coordinate of M’ and also of point M. The ratio between the distance FM’ and the distance FR (FM’/FR) defines the relative vertical coordinates of point M’ and point M, compared to the thigh length. The horizontal coordinate of point M is defined by Arch

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its distance from point M’ along the orthogonal projection line (ie, the absolute distance MM’). All measures, FR, FM’, and MM’, were made to the nearest half centimeter by the same investigator. The mean ratio FM’/FR and mean distance MM’ with standard deviation were calculated. RESULTS Twenty-nine dissections were done, 19 in the right thigh and 10 in the left thigh. The first 10 dissections were bilateral and for each subject we observed that the coordinates were the same in the right and in the left limb. A Student’s I test for matched pairs between different measures of the right limb and the left limb confirmed the absence of statistical difference between sides (p = .28 for MM’, p = .46 for ratio FM’/FR). After this observation, we decided to continue the dissection of the right limb only. The vastus intermedius nerve and point M were located in all subjects. It is a nerve branch coming from the division of the quadriceps nerve, which runs along the vastus intermedius muscle surface before penetrating into its depth in the high portion of the muscle. It is always lateral to the vastus medialis nerve and medial or joined to the vastus lateralis nerve. The point M coordinates are: 1. Absolute vertical coordinate: mean distance FM’ = 11.7 + 2cm. 2. Relative vertical coordinate: ratio FM’/FR = .29 -+ .04 (fig 2). 3. Horizontal coordinate: mean distance MM’ = 2 5 Scm (lateral to the segment FR) (fig 3). The vertical relative coordinate therefore is placed at 29% of the length from the point F, along the segment FR, and the horizontal coordinate is placed on average at 2cm lateral to the segment FR.

Fig 1. Schematic representation of the vasti and their nerves and anatomic landmarks. Point F is the issuing spot of the femoral nerve under the femoral arcade at one finger-width lateral to the femoral artery. Point R is the middle of the superior edge of the patella. Distance FR is the segment joining F and R, which indicates thigh height. Point M is the motor point of the vastus intermediate nerve. Point M orthogonal projection on segment FR defines the point M’. The distance FM’ is the point M’ and the point M absolute vertical coordinate (FM’ = FM). The horizontal coordinate of point M is the absolute distance MM’.

DISCUSSION In the anatomic literature, the vastus intermedius is described as having either one or three nerves. The principal nerve issues from the quadriceps nerve and enters the high part of the muscle. It is located between the medial vastus medialis and the lateral vastus lateralis nerves.4-6In this study, for each dissection we dissected a nerve of the vastus intermedius muscle, which always enters high in the muscle. Therefore, we think that this nerve is the principal nerve. The two other nerves, which are described as collaterals of the vastus medialis and vastus lateralis nerve and enter the low part of the muscle, were

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Fig 2. Histogram 1. Distribution of FM’/FR ratios.

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not dissected in our study. In this present work. the course and the position of the principal nerve were confirmed. The point M was always lateral to the segment FR. The chosen anatomic landmarks are easily identifiable. The issuing point of the femoral nerve under the inguinal ligament is at one finger-width lateral to the femoral pulse and is classically used in femoral nerve anesthesia.’ The superior edge of the patella is also easily found by palpation. The vertical coordinate would appear to be reliable. as the nerve penetration point in the muscle cannot be stretched in height by dissection. We think that the relative coordinate value is more accurate to find the point M because this method takes into account with the total thigh length, which is different for each individual. On the other hand, the accuracy of the horizontal coordinate is somewhat debatable because dissection may have displaced the nerve and the point M distance from the segment FR could have been overestimated. The problem of the depth has not been solved. The vastus intermedius nerve is located on the surface of the vastus intermedius and is covered by the rectus femoris muscle. Thus the depth depends on fat thickness and rectus femoris trophicity, which vary greatly from one subject to another. We have pointed out that the vastus intermedius nerve is frequently joined to or very near the vastus lateralis nerve. In our study, they are never farther than 2cm apart at the level of point M. It is not certain therefore whether a needle puncture could selectively point the vastus intermedius nerve. It is likely that a needle puncture would touch one or the other of the two nerves or the two nerves together. It seems unlikely, however. to also affect the vastus medialis nerve, which always lies medial to segment FR. To undertake the most selective block possible it would be useful to exactly locate the vastus intermedius nerve by an

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electrical stimulation during the needle puncture. For other nerve blocks (eg. tibia1 nerve. obturator nerve), electrical stimulation helps to better locate the nerve and increases the block precision and its efficiency. To validate this anatomic work in clinical practice, however, the efficiency and the selectivity of a vastus intermedius nerve anesthetic block will have to be tested.

CONCLUSION The motor point of the vastus intermedius nerve can be defined by two coordinates on the skin, a relative vertical coordinate and an absolute horizontal coordinate. Other studies are necessary to determine the clinical applications in quadriceps muscle spasticity treatment using an alcohol motor block at this motor point. References I. Kerrigan CD. Gronley J. Perry J. Stiff-legged gait in spastic paresis. A study of quadriceps and hamstring muscle activity. Am J Phys Med Rehabil 199 I ;70:294-300. 2. Enjalbert M. Viel E, Toulemonde M. Kotzki N. Pellissier J, Eledjam IJ. Neurolyse chimique h I’alcool (alcoolisation) et spasticite de I‘hemipltgique. Ann Readapt Med Phys 1993:36:337-42. 3. Barnes MN. Local treatment of spasticity. In: Ward CD, editor. Rehabilitation of motor disorders. London: Balliere Tindall; 1993. p. 55-7 I. Paturet G. Trait6 d’anatomie humaine. Paris: Masson; 1951. Bonnel F, Chevrel JP, Outrequin G. Anatomie humaine, les membres. Paris: Springer Verlag; I99 I. Rouviere H, Delmas A. Anatomie humaine, tome 3. Membres et systeme nerveux central: Paris: Masson: 1997. Lafaye PJ.-... Muller A. Anesthesie loco-regionale et traitement de la douleur: Parts: Masson; lYY6

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