I SOLATED observations regarding the occurrence of paresis of dorsiflexion

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1 MUSCLE WEAKNESS AND WASTING IN SCIATICA DUE TO FOURTH LUMBAR OR LUMBO- SACRAL DISC HERNIATIONS* ERIC KUGELBERG, M.D., AND INGEMAR PETERSI~N Deprtment of Clinicl Neurophysiology, Serfimerlsreet, Stockholm, Sweden (Received for publiction November s 1949) I SOLATED observtions regrding the occurrence of presis of dorsiflexion of either the gret toe or the foot, or of both, s n indiction of hernition of the 4th lumbr disc, were first reported by severl uthors. 12'13'1~'15 The fct tht definite dignostic conclusions regrding the level of the hernition could be drwn from the distribution of the presis ws shown in extensive studies by McKenzie nd Boerell, 9 nd Norl6n. u The firstmentioned pthors ributed wekness of the dorsiflexors of the nkle to lesion of the 5th hlmbr root (4th disc), nd of the plntr flexors to lesion of the 1st scrl root (5th disc). Norl6n further noted tht mong the dorsiflexors of the nkle nd toes, tht of the gret toe ws most commonly involved, being ffected in ~5 per cent of 56 cses with hernition of the 4th lumbr disc. In 48 ptients with lumboscrl disc hernition, however, there ws no wekness of dorsiflexion of the gret toe. Brdford nd Spurling I summrize the current conception thus--the 5th lumbr root, which is injured by the 4th lumbr disc hernition, is the lowest importnt root supplying the dorsiflexors of the foot nd toes, nd the 1st scrl root, which is injured by the lumboscrl disc hernition, is the highest importnt root supplying the plntr flexors. Hitherto only the long extensors nd flexors of the foot nd toes hve been studied, while the short toe extensors nd the remining smll muscles of the foot hve been disregrded. As the long motor nerve fibers to the peripherl prt of the extremities re more esily injured by vrious gents, e.g. ischemi, thn the short fibers to the proximl prts, ~' s we hve exmined the smll muscles of the foot in ptients with scitic. It ws found tht the short extensor of the toes is fr more frequently involved in 4th lumbr disc hernitions thn the long dorsiflexors, but is rrely ffected in lumboscrl disc hernitions. The condition of this muscle is therefore of considerble importnce in determining the level of the hernited disc, s preliminrily reported. 7 METHOD AND TECHNIC Mteril. The mteril consisted of 66 ptients with scitic dmied to the surgicl wrds for opertion. There were 44 men, nd ~ women. The oldest ws 65 yers of ge, dd the youngest ~1, with the verge ge over 4. The durtion of the symptoms vried from 1 month to 1 yers. * This study ws ided by grnt from the Swedish Medicl Reserch Council. 27

2 MUSCLE WEAKNESS AND WASTING IN SCIATICA ~71 In 41 ptients the disc hernition occurred between the 4th nd 5th lumbr vertebre, nd in ~5, between the 5th lumbr nd the 1st scrl vertebre. In every ptient opertion confirmed the dignosis of hernited disc. Technic. Ech ptient ws crefully exmined cliniclly by both uthors in regrd to wekness which, in the mjority of cses, ws lso nlysed electromyogrphiclly. In both these exmintions the ptient ws required voluntrily to contrct the muscles to the mximum. In ptients with incpciing pin the gretest cre ws tken to scertin whether true presis existed, or whether there ws merely functionl reduction of strength due to pin. Here the electromyogrm hs been vluble control, becuse the frequency of the individul ction potentils is good index of the degree of contrction. In electromyogrphy the current method of evlution hs been followed2 The muscles of both sides hve lwys been compred, nd only those with cler neurogenic chnges hve been regrded s bnorml. In the clinicl exmintions only definite wekness, compred with the sme muscle on the other side, hs been counted. It is difficult cliniclly to confirm presis in the short flexors nd extensors of the toes, owing to the dominting strength of the long muscles. We therefore hd to exmine the short muscles for trophy nd softness by plption, with the ptient mximlly flexing the toes ginst resistnce. The short toe extensors vry in size, but in norml cses neither symmetry nor pthologicl electromyogrphiel pictures hve been observed. In few cses the muscle ws difficult to exmine becuse of edem or ft, nd in these ptients the se of the muscle could only be evluted by eleetromyogrphy. The short toe flexors re considerbly more difficult to evlute cliniclly nd electromyogrphiclly thn the short toe extensors. Therefore no definite conclusions cn be drwn from exmintions of the flexor muscles. RESULTS 4th Lumbr Disc Hernition--.~l cses (Tble 1) Extensors of Foot z~d Toes. Some form of motor disturbnce--trophy, presis, or the electromyogrphicl picture of peripherl motor neuron lesion--ws found in 37 cses. The extensor digitorum brevis ws the muscle most often ffected(fig.l). In no.less thn 35 ptients either trophy ws clerly visible (Fig. 2) on the ffected side (23 cses), or there ws, on mximl contrction, plpbly softer consistency compred with the corresponding muscle of the other foot (12 cses). In 35 cses there ws lso electromyogrphicl evidence of lesion of the lower motor neuron. FIG. 1. Chrt showing distribution of motor disturbnces within the extensor group.

3 272 ERIC KUGELBERG AND INGEMAR PETERSI~N The electromyogrm gve, with one or two exceptions, the sme results s the clinicl tests, thus proving good control. There ws wekness of dorsiflexion of the gret toe in 19 cses, of dorsiflexion of the smll toes in 1~ cses, of dorsiflexion of the foot in 17 cses, nd of prontion of the foot in 8 cses (Fig. 1). The electromyogrphicl Fro. 2. Fourth lumbr disc hernition (Cse 85). The only clinicl sign ws extreme trophy of M. extensor digitorum brevis. (A) Affected foot. (B) Norml foot for comprison. FIG. 3. Fourth lumbr disc hernition. Electromyogrphic recordings of mximl voluntry contrctions from sme ptient s in Fig. 2. (A) Extensor digitorum brevis on norml side. (B) Sme muscle on ffected side, showing mrked diminution of motor unit ctivity. (C) Extensor hllucis longus on ffected side, showing pproximtely norml motor unit ctivity. (D) Tibilis nticus on ffected side, showing norml motor unit.ctivity. Time: 1/1 sec. Clibrtion: 1V. control of the M. extensor hllucis longus, M. tibilis nterior nd M. peroneus longus corresponded in the mjority of cses to the clinicl findings. If there were elcctromyogrphicl chnges in severl muscles t the sme time they were nerly lwys more pronounced in the short extensors of the toes (Fig. S). Motor disturbnces re, s lredy mentioned, most common in the short toe extensors. In ~ ptients, however, the M. extensor digitorum brevis showed norml clinicl findings t the sme time s there ws presis of one or two long extensors. In both these cses, however, the clectromyogrphicl picture ws pthologicl. The muscles of the non-operted side were norml, except in few ptients who hd previously hd lternting right- nd leftsided pin.

4 MUSCLE WEAKNESS AND WASTING IN SCIATICA ~73 TABLE 1 Fourth Lumbr Disc Hernition Cse No. M. ext. dig. brev. Dorsl Flexion of Gret Toe Dorsl Flexion of Foot Dorsl Flexion of Toes 7 Prontion of Foot Plntr Flexion of Foot & Toes Achilles Reflex 1 `2 3" ' '2'2 Norml Reduced muse. consistency Atrophy Norml Presis Norml Presis Norml Presis Norml Presis Norml Presis Norml Norml Presis Norml Presis tr Norml Norml Presis Norml Presis Norml Presis Norml Presis Norml Norml Presis Norml Presis Norml Norml Presis (toes) Norml Presis (foot) Norml Presis (foot) Norml Norml Wekened Norml Wekened Norml Norml ~24 '25 ~6 '27 '28 "29 3o 3' Presis Norml Presis Norml Presis g~ Presis 11 Norml Presis Presis Norml Presis Norml Presis Norml Presis Presis Norml Presis Presis (foot) Norml Wekened Norml Norml * Sensory root section of S1 performed erlier. t L5 nd S1 roots compressed.

5 r ERIC KUGELBERG AND INGEMAR PETERSI:]N Flexors of the Foot nd Toes. In 5 cses there ws presis of the plntr flexors of the foot nd toes. In ~ of these compression of L5 s well s $1 roots ws found t opertion. In ll cses of flexor presis there were lso disturbnces of the extensor group (Fig. 4). Achilles Reflex. This reflex ws norml in 31 cses, wekened in 3, nd bsent in 7. In 1 cse with bsent nkle jerk, rhizotomy of the $1 sensory nerve root hd been performed erlier. Our results regrding the bsence of the Achilles reflex in the L5 syndrome corresponded to reports from other uthors, J1,16 Fro. 4. Distribution of clinicl motor disturbnces in 4th (41 cses) nd 5th ('25 cses) lumbr disc hernition, TABLE o~ Lumboscrl Disc Hernitions lthough we did not find diminu- tion of the Achilles reflexes so frequently. Cse No. Atrophy of M. ext. dig. brev. Presis of Extensors of Foot nd Toes Presis of Flexors of Foot nd Toes Achilles Reflex 1 ~ ` ~" `23 ~4 "25 o o o Slight Slight All toes o Gret toe Foot nd gret toe I Norml Wekened Norml Wekened Norml Wekened Norml Wekened Wekened * The roots below S1 were compressed.

6 MUSCLE WEAKNESS AND WASTING IN SCIATICA ~75 Lumboscrl Disc Hernitions--25 cses (Tble 2) Motor Disorders. In ~1 of the ~5 ptients there ws no clinicl wekness or wsting of the flexors or extensors of the foot nd toes. Of the remining 4 ptients, ~ hd wekness of the long plntr flexors, nd ~ hd slight wsting of the extensor digitorum brevis, in 1 cse combined with wekness of the dorsiflexors of ll toes. Compred with the 4th lumbr disc hernitions, the motor chnges in lumboscrl disc hernitions re strikingly sprse (Fig. 4). The Achilles Reflex. This ws bsent in 13 cses, wekened in 8 cses, nd norml in 4, corresponding well with the findings of erlier uthors. 11,1~ DISCUSSION In our mteril only those ptients hve been included in whom the dignosis of hernited disc ws confirmed t opertion. The results cnnot therefore be directly pplied, for exmple, to disc hernition mteril from n outptient deprtment where greter number of mild cses re seen. The clinicl dignosis of the level of the disc hernition cn, of course, be crried only to certin point. Definite dignostic signs nd symptoms my be completely bsent, or the prolpsed disc my compress severl roots t the sme time (No. 31, Tble 1) ; root other thn tht expected my be compressed (No. ~, Tble ~); or the symptoms my be typicl, possibly becuse of devitions from the norml in the ntomicl composition of the root (No. 9, Tble ~). These re exmples from our mteril of fctors tht limit the clinicl possibilities. Usully, however, it is possible to determine the level cliniclly. The motor symptoms re importnt here, nd the principl object of this study is to show the remrkbly common ffection of the M. extensor digitorum brevis in 4th lumbr disc hernitions. In fct, it ppers to be the most constnt sign of disc hernition t this level. No detiled study on the distribution of the sensory disturbnces hs been mde in our work, which is primrily directed towrds motor disorders. However, judging from the literture, rditing pin or impirment of sensibility, with distribution referble to definite single root, do not occur in such lrge percentge of cses. Nevertheless, it is cler tht ll the signs nd symptoms must be collected nd evluted in ech ptient. The exmintions further show tht the short extensor of the toes hs its min nerve supply from roots bove $1, nd tht it is not s rule ffected in lumboscrl disc hernitions. In 1 cse with n S1 root syndrome explortion reveled neurinom, nd the nerve hd to be divided. In spite of this there were no clinicl or electromyogrphicl signs of involvement of the short extensor. Conversely, there re mny cses in our mteril where the short extensor of the toes hs been extremely wsted without ny electricl ctivity on empted voluntry contrction. Explortion reveled only compression of the 5th lumbr root, indicting tht the min nervous supply of the short extensor cme from LS. Our findings do not support the opinion

7 s ERIC KUGELBERG AND INGEMAR PETERS]~N tht the muscle is innervted from S1 nd Ss (Hymker nd Woodhll, 3 nd others1~ but compre beer with most textbooks, which suggest L4, L5, nd S1. The r:mre constnt involvement of the extensor brevis, compred with the long dorsiflexors of the foot nd toes, is not due to the exmintion technic, since the electromyogrm clerly shows tht the short extensors re ffected more thn the long extensors. This difference my be due to less segmentl overlp in the innervtion of the muscles in the distl prt of the extremity thn in the proximl, s is ssumed for sensory innervtion (Keegn, 4 Flconer et l.2). Another possibility is the greter vulnerbility of the long nerve fibers compred with the shorter ones, s found, for instnce, in experimentl ischemi on the humn rm (Lewis, Pickering nd Rothschild, s nd Kugelberg.5). In fct, if the circultion to the leg is rrested by compression with pneumtic cuff, within the extensor group the short extensor is prlysed first, followed in order by the extensor hllucis longus, the extensor digitorum longus, the tibilis nterior, nd the peroneus longu,~. SUMMARY Sixty-six ptients with scitic due to 4th lumbr (41 cses) or lumboscrl (~5 cses) disc hernition verified by opertion, hve been exmined for musculr disturbnces in the lower leg nd foot. 1. 4th Lumbr Disc Hernition. In 9 per cent of the cses the muscles within the extensor group were ffected with the following distribution: M. extensor digitorum brevis in 85 per cent (trophy or plpbly soft consistency on mximl contrction); M. extensor hllueis longus in 46 per cent (wekness); M. tibilis nterior in 41 per cent (wekness). In 13 per cent of the cses there ws wekness of the muscles of the flexor group. In these cses there were lso disturbnces of the extensor group. ~. Lumboscrl Disc Hernition. In only 16 per cent of the cses were the muscles ffected, with wekness nd wsting of those of the extensor group in 8 per cent, nd of the flexor group in 8 per cent. 3. The cuse of the strikingly common ffection of the M. extensor digitorum brevis in 4th lumbr disc hernition is discussed. REFERENCES 1. BRADFORD, ~F. K., nd SPURLIN~, R. G. The intervertebrl disc with specil reference to rupture of the nnulus fibrosus with hernition of the nucleus pu posus. Springfield, Ill.: Chrles C Thoms, 1945, 2d ed., 192 pp. 2. FALCONER, M. A., GLASGOW, G. L., nd COLE, D.S. Sensory disturbnces occurring in scitic due to intervertebrl disc protrusions: some observtions on the fifth lumbr nd first scrl dermtomes. J. Neurol. Neurosurg. Psychit., 1947, n.s. 1: HAYMAKER, W., nd WOODRALL, B. Peripherl nerve injuries. Principles of dignosis. Phildelphi & London: W. B. Sunders Co., 1945, xiv, ~s pp. 4. KEEOA~, J. J. Dermtome hyplgesi ssocited with hernition of intervertebrl disk. Arch. Neurol. Psychit., Chicgo, 1943, 5: KVC, ELRER(r,, E. Accommodtion in humn nerves nd its significnce for the symptoms in circultory disturbnces nd tetny. Act physiol, send., 1944, 8: supp. 24, 15 pp.

8 MUSCLE WEAKNESS AND WASTING IN SCIATICA ~77 6. KUGELBERG, E. Electromyogrms in musculr disorders. J. Neurol. Neurosurg. Psychit., 1947, n.s. 1: 1~2~ KUGELBERG, E., nd PETERS~;N, I. Preser vid L: 5 och S: 1-syndromen. Nord. reed., 1949, 41: 74!. 8. LEWIS, T., PICKERING, G. W., nd ROTftSCHILD, P. Centripetl prlysis rising out of rrested bloodflow to the limb, including notes on form of tingling. Hert, 1931, 16: 1-3~. 9. ]V[cKENzIE, K. G., nd BOTTERELL, E.H. The common neurologicl syndromes produced by pressure from extrusion of n iutervertebrl disc. Cnd. reed. Ass. J., 194s $6: 4~ MEDICAL RESEARCH COUNCIL: NERVE INJURIES COMMITTEE. Aids to the investigtion of peripherl nerve injuries. M. R. C. Wr Memo. No. 7. London: His Mjesty's Str. Off., 194% 48 pp. 11. NORL~N, G. Oil the vlue of the neurologicl symptoms in scitic for the locliztion of lumbr disc hernition. A contribution to the problem of the surgicl tretment of scitic. Act chir. scnd., 1944, 91 : supp. 95, 96 pp. 14. PENNYBACKER, J. Scitic nd the intervertebrl disc. Lncet, 194,1: SJOQVIST, O. De lumbl diskbr~cken. Klinisk dignos sint exstirption utn lminectomi. Nord. reed., 194~, 13: SPURLING, R. G., nd BRADFORD, F.K. Neurologic spects of hernited nucleus pulposus t the fourth nd fifth lumbr iuterspces. J. Amer. reed. Ass., 1939, 113: ~19-~~. 15. SPURLING, R. G., nd GRANTHAM, E.G. Neurologic picture of hernitions of the nucleus pulposus in the lower prt of the lumbr region. Arch. Surg., Chicgo, 194, $: WARIS, W. Lumbr disc heruition. Act chit. scnd., 1948, 97: supp. 14, 134 pp.