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Show Ii) 1985 Raven Press, New York Isolated Facial Myokymia and Facial Contracture: Computed Tomography and Magnetic Resonance Imaging Correlation MICHAEL P. MERCHUT, M.D. JosE: BILLER, M.D. JOEL BRUMLIK, M.D., Ph.D, BEHROOZ AZAR-KIA, M.D. ERIC J. RUSSELL, M.D. Abstract Isolated facial myokymia with contracture can be the earliest manifestation of intrinsic lesions of the brainstem. We report a case of facial myokymia with contracture occurring as the result of a pontine glioma, as depicted on cranial computed tomography and magnetic resonance imaging studies. The rostral location of the tumor supports the supranuclear disinhibition hypothesis of facial myokymia. Facial myokymia is a condition of continuous, fine, undu'lating movements of the face caused by spontaneous contraction of one or ml)re facial muscles. If restricted to the evelids, nwokymia may be considered a benign conditi~m, However, more generalized facial involvement, especially if facial contracture is also present, suggests demonstrable brainstem pathologv y~ Although the pathophysiologic mechanism underlying facial myokymia is unknown, supranuclear disinhibition of the facial nucleus h,1s been hypothesized, We report a caSt' of facial myokymia with contracture and computt'd tomography (CT) and magnetic resonance imaging (MRI) evidence of tumor involvement III the brainstl'm rostral to the facial nuclt'us, thus hom Ihl' ()l'p,lrln1l'nh 01 N,'un,log\' (M,[',~I.. I, Ilrull1li\..) ,10.1 R"diology (B,A-K,), 1.01'01,1 Uni~','rsit\' ~kdic,ll C,'nl"r, M,ll',,"ood, Illinois, D,'pMI'n1l'nl III Nl'urlll,'g\' (J, Ililkr!. Univ,'rsily "I I"W,', I"",,, Cil\', 1""",1. ,lIld 1),'"p.Hln1l'nl III R"Ji"l"gy 0:1,1< ), Rush !'rl'sb\'!l'ri.ln-Sl lu\..,'s M"dic.11 (,'n"'r. Chl,'"g". IlIln"is, Wnl,' /",. ""/'1'/1/1, I,,: " Ilill"r. ~1.1 I" ()l'f'Mln1l'111 "l N"urol" gy, Univl'rsity "I low" II"spil"ls. 111\\,,1 Cil\'. 1/\ 52242. U,~,A, ' 120 supporting the hypothesis of supranuclear facial disinhibition, Case Report A 26-year-old woman complained of continuous, painless "twitching" of her right eyelid and mouth for about -1-6 weeks, This was appreciated by others more readil~' than by herself. Aside from occasional headaches, she had no history of the same or other neurological problems. The ph~'sical examination was unremarkable except for persistent mvok~'mia of the right orbicularis oculi, buccinator, orbicularis oris. mentalis, and platysma. The right palpebral fissure was narrowed and the right nasolabial fl)ld deepened. Facial sensation and strength were intact. Corneal, sneezing, and masseter reflexes were preserved. The remainder llf the general neurological and physical examinatil1l1 was normal. Electromyography revealed numerous iterative discharges of the orbicularis oris lasting 1.5-1. 75 s. Each discharge was produced by single motor units firing either individually or in cl)njunction with another motor unit. The firing rate \-vas 36-63/Hz against a rather steady background firing at 201Hz. Occasionally, there were pwgressive changes in interval (and more rarely in frequency), pwducing a sound reminiscent of mY.lltonic discharges. ElectricallyelicIlt'd blll1k retlex revealed an absent Rl (early) COmpl1l1ent on the right, and normal R2 (late) component bilaterallv. Visual evoked, sl;matosensory, and brainstem auditory evoked potentials 'were normal. Cranial CT ~howed a low-density area on the nght Side ot the upper pons extending super- iorly toward the right cerebral peduncle, with obliteration of the right side llf till' ambient cistern (Fig. 1). MRI was done in the tranSVl'rSl' axial plane and midsagittal pl,1l1t', through till' posterior fossa. A spin echll image (Fig. 211) demonstrated focal e'p,lI1sitll1 tlf the superior portion of the right cerdwal pedunclt' and upper pons by a low-intensity (dark) mass. Spin echo and inversion reco\"t'ry images (Fig. 2/J and 2c) sho\'\'ed exoph~rtic extension of the mass within the right ambient cistern. The rt'm,lindt'r of the brainstem, including the hl\ver pons, WilS nllrmal. The imagt' characlt'ristics were consistent with the prohll1ged Tl and T2 often seen in cases of brainstem neoplasia. Fllur-vessel cerebral angiographV was unremarkable. The patient underwent focal radiation therapy to the mass, receiving 5,580 rad in 31 fractions (180 rad each) over a -B-day period (7.5 '< 6.0 cm pl1rt, III MeV photon source). She has been stable after 6 months, except for development of a mild facial paresis, evident on attempted movement of the face. The tonic contracture and myok~'mia are unchanged. Discussion Following the description of Bernardt.1 in 1902, the finding of facial myokymia subse- Figure 1. Area of lucency (arrows) in the right side of till' upper brainstem causing obliteration of the ri~ht ambient cistern and deformity of the fourth wntricll'. After infusion of contrast, no enhancement was detected. June 1985 Merchut et al. quently was considered pathognomonic for multiple sclerosis. Several cases due to brainslt'm tumors have since been reported. In 43 caSl'S of facial myokymia, 42'j, were associated with multiple sclerosis and 14'j, with brainstem or poskrior fossa tumors. The remaining 44% includl'd cases of vertebrobasilar ischemia, polyradiculoneuropathy, hemifacial spasm, peripheral facial paralysis, trigeminal neuralgia, syringobulbia, abortive Little's disease, phosgene poisoning, and amyotrophic lateral sclerosis. As a manifestation of multiple sclerosis, facial myokymia usually occurs transiently, lasting from days to months, and may present alternatingly but on different occasions on either side of the face. Nuclear or supranuclear facial weakness often coexists but is mild. On electromyography, spontaneous, rhythmic, motor unit discharges are commonly continuous but asynchronous between adjacent facial muscles. 1 In the case of brainstem tumors, facial myokymia is typically unilateral and of longer duration, until it is replaced by a more severe and progressive facial palsy. Discontinuous motor unit bursts are found on electromyography, as in our case. Tumor size does not correlate well with the extent of facial musculature involved by myokymia. I In the rare instance when myokymia involves several cranial nerves, the tumor has substantial rostral-caudal involvement of the brainstem 4 Various mechanisms have been proposed to explain tumor-related facial myokymia. One hypothesis concerns the loss of interneurons that synapse on neurons of the facial nucleus. Loss of such inhibitory or dampening influences would allow the nonreflexic, high neuronal firing rate to occur, as seen on electromyography." The second hypothesis suggests disinhibition of the facial nucleus bv ItlsS of more rostral supranuclear, especiall\; corticobulbar, pathways. The radiologic findings in our caSt' f,H'or the latter hypothesis. Tumor ILlCalizatil1l1 to the upper pons and midbrain would interrupt the corticobulbar pathways to the facial nucleus, sparing the nucleus itself or adjacent interneurons. Though autopsv m,ltt'ri,ll is rart" tWll patients with f.Kial mvokvmi,] had rostral brainstem lesions with s~~arii1g of the f,Kial nucleus, supporting the hypothesis of supranuclear disinhibition.~ ·h A third C,lSt' was verv similar, but edema and gliosis of the facial nliCleus complicate the interprt'ldtitlIl.' Only llIle or two previous cases of brainstem tumor' apparently presented solely with facial 121 CT ,1I1d MRI in r,ll"i,ll Mvo!-. vmi,l ,1I1d Cllnlr,Klurt' myokymia and contracture, without paresis./l,Q A mild facial paresis may evolve later, as in our patient. Occasionally, facial paresis and tonic contracture coexist without myokymia in cases of brainstem glioma, III Our case report is most intriguing because of 122 IbJ Figure 2. Magnetic resonance images performed with 0.5 T superconducting sYstem ,7 Spin echo 30 :;00, axial image. at the Ie\'eI of the cerebral peduncles. ~l)te the low signal mass (arrows) within the right peduncle. compressing the adjacent ambient cistern I"~ Spin echo 120 WOO, axial image. at the same lew! as (tl). The mass nl'W appears white (high intensit\') due primarih' to prolonged T2. c Inyersion recoven' -!:;o 301:;00 axial image. ~e)te e,cellent gray mailer white mailer discriminatie)n and sharp demarcation of the e",pln-tic peduncular lesilm. The Ie)\\" signal l)f the mass (arrows) is primarih' due ll) a pTl)!lmged Tl. the paucity of neurological signs in spite of extensive tumor involvement of the upper pons and cerebral peduncle, as shown by CT and MRI. The paucity of neurological findings, belies the extensive tumor infiltration of brainstem tracts prior to neuronal destruction. Journal of Clinical Neuro-ophthalmology Acknowledgment The authors wish to th,mk Marl:Y Young and LiS,l Gustafson for their assistanl:l' in manusnipt preparation. References 1. Radu, R. W., Skorpil V., and Kaesl'r, H. E.: F,lI: ial myokymia. Eur. Nl'urtll. 13: -!94-512, 1975. 2. Sethi, ·P. k., Smith, B. H., and K,llyanMam,ln, K.: Facial myokymia: a dinil:opathl)ll~gical study. /. Nt'urt11. Nt'unJsur...;. Psychiatry 37: 7-!5-7-!9, 1974. 3. Bernhardt, M.: Ein ungewohnlil:her F,lll \'on Fazialiskrampi. Nt'Urtll. LN. 21: b7tl-b45, 1902. -!. Kaeser, H. E., and Skorpil, V.: Myokymia in\' l)lving the musdes innervated by tl-il' V'th, Vlth, VIIth, IXth, Xth. Xlth and Xlltl-i I:ranial nerves with brain stem tumor. Eur. Nt'urtll. 14: -!Otl--!12, 1976. June 1985 Merchut et al. 5. O'Connor, P. j., Wynn Parry, C B., and Davies, R.: Continuous musde spasm in intramedullary tumours of the neuraxis. ,. Nl'urol. NCl/rosl/rg. PSyc/liatn{ 29: ]]()- 314, 1966. 6. Bogl1l'n, D., Filiatrault, R., and Descarries, L.: Myokymi,) and fal:ial contracture in brain stem tubl'rculoma. Ncurotogy27: 270-272, 1977. 7. Waybright, E. A., Gutmann, L., and Chou, S. M.: Facial myokymia: pathological features. Arc/I. Ncurot. 36: 2-!4-245, 1474. H. Tenser, R. S., and Corbett, J. j.: Myokymia and fad,ll contraction in brain stem glioma. Arch. Nt'llrot. 30: -!25--!27, 1474. 9. Negri, S., Caraceni, T., and De Lorenzi, L.: Facial myokymia and brain stem tumor. EI/r. NCI/rot, 14: lli8-118,1976. 10. Sogg R. L., Hoyt W. F., and Boldrey, E.: Spastic paretic facial contracture: a rare sign of brain stem tumor. Nellrotogl{13: 607-612, 1963. 123 |
