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J7ournal of , Neurosurgery, and Psychiatry 1992;55: 1089-109 1 1 089 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.11.1089 on 1 November 1992. Downloaded from SHORT REPORT "Isolated" postinfectious myoclonus

K Bhatia, P D Thompson, C D Marsden

Abstract abnormality on clinical examination or inves- Two cases are reported who developed tigations and the myoclonus is usually short myoclonus as the only manifestation of a lasting. Although post-infectious post-infectious syndrome without evi- as a cause of myoclonus has been included in dence of encephalitis or the - lists of aetiological classifications,3 12 13 the myoclonus syndrome. Case 1 had syndrome of isolated myoclonus following generalised myoclonus following an influ- infection has not been clearly defined. In the enza-like illness, while case 2 had right past such patients have been referred to ambig- upper limb segmental myoclonus follow- uously and one report'4 included them within ing uncomplicated chicken pox. Neither a group labelled "myoclonus without had any localising neurological signs or or neurological or mental deficit." We report abnormality on investigation. Both recov- two cases with myoclonus as the sole manifes- ered completely within six months of the tation of a post-infectious syndrome, and have onset. Similar cases are reviewed from the reviewed the few similar cases from the lit- literature and it is suggested that such erature. cases be called "isolated" post-infectious myoclonus. Case reports (7 Neurol Neurosurg Psychiatry 1992;55: 1089-109 1) Case 1 A 23 year old woman, presented with a 14 week history of an influenza-like illness dominated by generalised body ache, lethargy Myoclonus can be a clinical feature of many and fever. Two weeks after the onset she infectious encephalitides and was notable in developed episodic generalised jerks of the the acute and chronic phases of epidemic arms and legs, each lasting for up to 30 .' More recently it has seconds, and occurring every two hours or so, been recognised as a pathognomonic feature of without loss of consciousness, or other epi- subacute sclerosing panencephalitis2 and leptic phenomena. She was otherwise normal Creutzfeldt-Jacob disease.2 Myoclonus has between attacks. Treatment with also been described in acute encephalitis due improved the but made her very

to a variety of viral24 and non-viral agents` drowsy. When discontinued 2 weeks later, the http://jnnp.bmj.com/ which either directly invade the CNS, or by an spasms became more intense and responsive to immunological process cause an acute dis- noise, sudden movement and startle. She also seminated (also called post- developed constant twitching of her arms and infectious encephalitis). In either case, the legs making it difficult for her to use her hands, clinical picture is of an acute illness charac- walk, and speak. She was investigated else- terised by seizures, alterations in conscious- where at this stage. An EEG carried out ness, and focal neurological signs. Myoclonus, showed runs of polyspike/spikes at about 5/6 on September 30, 2021 by guest. Protected copyright. when present, is usually only a minor feature of per second, associated with the episodes of the overall clinical syndrome. If the patient jerking. CT scan of the head and CSF exam- survives the acute illness the myoclonus usually ination at that time were normal. She was disappears. Segmental myoclonus following treated with which benefitted her herpes zoster infection is also well known8 9 initially, but she developed tolerance to it, as and is usually transient. The opsoclonus- she did to propranolol which was tried next. At myoclonus or the "dancing eyes and dancing this stage, when seen in our department, she The Institute of is a brain stem had the attacks only once or twice a Neurology and The feet" syndrome encephalitis jerking National Hospital for preceded or associated with a variety of known day. However, she had spontaneous, repetitive Neurology and and often unknown infectious agents.'o " This wriggling jerks of arms, legs, and head, lasting Neurosurgery, Queen self limiting condition is easily recognised many minutes and increasing on . At the Square, London, UK K Bhatia because of the association of the myoclonus beginning of her examination, she could not P D Thompson with the characteristic eye signs. walk because of the jerking of her legs. She also C D Marsden Here, we draw attention to patients who had almost continuous rhythmic multifocal Correspondence to: or focal as an myoclonus ofboth arms, and occasional bursts Professor Marsden, Institute develop generalised myoclonus, of Neurology, Queen isolated phenomenon, after a mild illness of titubation of the head. Twenty minutes later Square, London WCIN (probably viral) without any features of ence- the large jerks gradually settled and dis- 3BG, UK or of the syn- appeared. She could then walk normally heel Received 28 November 1991 phalitis opsoclonus-myoclonus -Accepted 23 January 1992 drome. These patients have no other to toe and hop on either leg. The rest of the 1 090 Bhatia, Thompson, Marsden J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.11.1089 on 1 November 1992. Downloaded from

CNS examination revealed no abnormality in liver function tests, calcium, copper and caer- tone, power, and deep tendon reflexes with the uloplasmin, thyroid function, ANF and plantar responses being flexor and sensation autoantibodies were all normal or negative. A normal. She was advised to take sodium CSF examination was not done because the 500 mgs, to which she showed an patient was unwilling to undergo a lumbar excellent response and the myoclonus subsided puncture. A CT scan of the head was normal. almost completely in a few months. The patient recovered completely within 6 months. Case 2 A 14 year old girl presented with myoclonic jerking of the right arm, two weeks after the onset of uncomplicated chicken pox Discussion which resolved in about 10 days. The jerking of Generalised myoclonus developed in case 1 the arm progressively got worse and reached its following an influenza-like illness whilst case 2 peak after three weeks making the use of her developed segmental myoclonus following right hand difficult, especially for writing. The uncomplicated chicken pox. Neither patient jerking worsened when she was anxious or had altered consciousness, seizures, or other tired. She had no weakness or sensory symp- clinical signs to suggest an acute encephalitis toms in that arm. Five weeks after the onset or . Myoclonus was the sole manifesta- when seen by us she had begun to notice some tion of their post-infectious syndrome. We improvement. Her past medical history was suggest that the term isolated post-infectious unremarkable. myoclonus is appropriate to describe the On examination higher mental function was myoclonic syndromes exhibited by these two normal as were the cranial nerves. There were patients and in others who satisfy the following occasional jerks of the right triceps, brachior- criteria: 1) A sudden onset of generalised, adialis, wrist and finger extensors and biceps multifocal or segmental myoclonus; 2) a his- with sparing of the spinati and pectorals. Some tory of a recent preceding infectious illness; 3) jerks appeared myoclonic while others were no features of encephalitis or the opsoclonus- longer lasting and resembled tonic spasms. The myoclonus syndrome; 4) a non-progressive jerks increased on sustained posture. There course without seizures, ataxia, or was no stimulus or action sensitivity. Occa- and 5) recovery in a short but variable period sional dystonic posturing of the right hand was of time. also noted. On one occasion she was seen to A number of similar cases are described in have some jerks of the left upper and lower the literature where myoclonus developed fol- limbs but this was not a repeated observation. lowing presumed viral infections of the upper There was no wasting, and the tone, power and respiratory tract or following an influenza-like reflexes were normal. The deep tendon reflexes illness (table'4"7). The interval between the and plantar responses were normal and there initial illness and the onset of myoclonus was was no sensory deficit. General examination short. None of these cases had any focal was normal except for a mild thoracic scoliosis neurological signs. The course of the condition with convexity to the left. was benign and the prognosis good. Both our Electrophysiological investigation showed a cases recovered in about six months and most single long duration burst and short trains of 3 in the literature recovered over a period of bursts betwen 50 and 100 milliseconds in the weeks. Silfverskiold'7 described three young

right brachioradialis and triceps muscles. girls with the subacute onset of rhythmic http://jnnp.bmj.com/ Back-averaging the EEG activity preceding the myoclonus of upper and lower limbs who had jerks did not show any time locked cerebral no preceeding illness. Although there was no events. Cortical somatosensory evoked respon- definite evidence of previous infection, they ses were of normal latency and morphology. were presumed to be post-infectious on epide- Magnetic stimulation of the motor cortex miological grounds, because all three lived in produced normal responses in the right arm. the same area, and developed a similar benign There was no stimulus sensitivity to percussion myoclonic syndrome in the autumn of 1958. on September 30, 2021 by guest. Protected copyright. or electrical stimulation of the median nerves. All recovered over 6 to 18 months of onset. EEG showed some asymmetry in the activity There are other cases in the literature of between the hemispheres with better formed myoclonus attributed to preceding infec- " alpha activity on the right. In addition, there tions." In a large survey of myoclonus, were some runs of slow activity on the right. Lance"8 described one patient (case 34) who Full blood count, ESR, renal function tests, developed generalised action myoclonus,

Table Summary of the clinical characteristics and duration of myoclonus in cases of isolated post-infectious myoclonus reported in the literature. The preceding iUlnesses and the interval between this illness and the onset of myoclonus are also given Authors Age Sex Antecedent illness Interval Characteristics Duration Otherfindings Aigner & Mulder" (Four patients) Not stated Not stated "Flu" Not stated Not stated Not stated Not stated Campbell & Garland" (Case 2? 35 M "Sore throat" 1 day Segmental (abdominal) Days Fever, leukocytosis Bradshaw 6 "lyoung" F "URTI" Not stated Lower trunk, thighs Days Silverskiold'' 8 F None - Multifocal; rhythmic Weeks EEG normal 16 F ?Streptococcal infection ? Multifocal; rhythmic Months EEF normal 12 F None - Trunk, limbs; asynchronous Weeks Isolated postinfectious myoclonus 1091 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.11.1089 on 1 November 1992. Downloaded from ataxia and an abnormal EEG two weeks after a We thank Dr R F Gledhill for referring case 2. presumed meningoencephalitic illness with complete recovery over the ensuing three weeks. Hopkins and Michael"9 described a 36 1 Von Economo C. Encephalitis letharigica: its sequelae and year old male who developed rhythmic myoclo- treatment. London: Oxford University Press, 1931. nus 2 Farrel DF, Swanson PD. Infectious diseases associated with of the pelvis and lower limbs which lasted myoclonus. In: Charlton MH, ed. Myoclonic seizures. one week, was associated with absent knee and Amsterdam: Excerpta Medica, 1975:77-110. 3 Marsden CD, Hallett M, Fahn S. The nosology and ankle jerks and electrophysiological evidence pathophysiology of myoclonus. In: Marsden CD, Fahn S, of a spinal origin for the myoclonus. There was eds. Movement disorders. London: Butterworth, no 1982:196-248. history of a preceding illness but a CSF 4 Parain D, Boullocke J. Multifocal epileptic crises following pleocytosis and raised protein level suggested a mumps. Neurophysiol-Clin 1988;18:87-91. recent (probable 5 Swanson PD, Luttrel CN, Magladery JW. Myoclonus-A viral) infection. These report of 67 cases and a review of the literature. Medicine patients did have evidence of CNS inflamma- 1962;41 :339-56. tion and 6 Marinesco MG. Report on a case of myoclonic encephalo- (encephalitis"8 myelitis"9) and so were myelitis of malarial origin. Brain 1921;44:223-33. excluded as examples of isolated post-infectious 7 Steiner I, Polacheck I, Melamed E. Dementia and myoclo- nus in a case of cryptococcal encephalitis. Arch Neurol myoclonus according to our criteria. 1984;41:216-7. Why some patients should develop myoclo- 8 Dhaliwal GS, McGreal DA. Spinal myoclonus in associa- nus without clinical or investigative evidence of tion with Herpes Zoster infection: Two case reports. Can J Neurol Sci 1974;1:239-41. structural damage of the CNS following non- 9 Hoehn MH, Cherington M. Spinal Myoclonus. Neurology specific or uncomplicated infectious illnesses is 1977;27:942-6. 10 Kinsbourne M. Myoclonic of infants. J unclear. The pathophysiological origin of the Neurol Neurosurg Psychiatry 1962;25:271-6. in our 11 Kuban KC, Ephros MA, Freeman RL, et al. Syndrome of myoclonus two cases is uncertain. Case opsoclonus-myoclonus caused by Coxsackie B3 infection. 1, with generalised myoclonus, on one occa- Ann Neurol 1985;13:623-4. sion was found to have runs of 12 Fahn S, Marsden CD, Van Woert MH. Definition and polyspike/spike classification of myoclonus. In: Fahn S, et al. eds. potentials at 5-6 Hz on EEG corresponding to Advances in neurology, Vol 43, Myoclonus. New York: her jerks pointing towards a Raven Press 1986:1-5. probable cortical 13 Weiner WJ, Lang AE. Myoclonus and related disorders. In: origin of the myoclonus. In case 2, back- Weiner WJ, Lang AE, eds. Movement disorders, a compre- hensive survey. New York: Futura Publishing averaging of the EEG did not reveal any 1989:457-530. cortical correlates nor did she have enlarged 14 Aigner RB, Mulder DW. Myoclonus, clinical significance and an approach to classification. Arch Neurol somatosensory evoked potentials, suggesting 1960;2:600-15. that the myoclonus was probably not of cort- 15 Campbell AMG, Garland H. Subacute myoclonic spinal neuronitis. J Neurol Neurosurg Psychiatry 1956; ical origin. No EEG correlates corresponding 19:268-74. to the myoclonic jerks were reported in Silfver- 16 Bradshaw JPP. Cited by Liversedge LA; Involuntary move- skiold's cases with rhythmic upper and ments: In:Vinken PJ, Bruyn GW, eds. Handbook ofclinical lower neurology, Vol 1. Amsterdam: North Holland Publishing, limb myoclonus. 7 As might be expected there- 1969:277-92. fore it 17 Silverskiold BP. Rhythmic myoclonus in three girls. Acta appears that post-infectious myoclonus Neurol Scand 1969;38:45-9. is a heterogenous entity and that different sites 18 Lance JW. Myoclonic jerks and falls: aetiology, classification of the CNS can be and treatment. Med JAust 1968;4:113-20. affected. The underlying 19 Hopkins AP, Michael WF. Spinal myoclonus. Jf Neurol pathology is also uncertain. Neurosurg Psychiatry 1974;37:1112-15. http://jnnp.bmj.com/

Early notions of The eighteenth century anatomists Morgagni, and

the physician Robert Whytt demonstrated the relevant on September 30, 2021 by guest. Protected copyright. The truth of claims that Hippocrates recognised hydro- CSF pathways and made cephalus and drained the ventricles through the fonta- some sense ofthe pathology of nelle hydrocephalus.' is uncertain. Two patients are described in the In the nineteenth century Magendie second edition ofVesalius' De Fabrica (1555)': in a two (1828), Luschka old (1855) and above all, Key and Retzius described the year girl he had obtained "9lbs of water from the CSF flow and formation. In his "Essay on hydrocepha- ventricles. I marvelled at nothing more than the amount lus acutus" ofwater had for so (1808), John Cheyne recorded 23 cases; all long collected in the ventricles of the but six succumbed and the aetiology in most was brain without greater symptoms." probably tuberculous .' In 1761 Contugno described the JMS PEARCE (CSF).' The remarkable Stockholm mystic, Emmanuel Swedenborg (1688-1772), left manuscripts unpub- lished until 1882 and 1887 showing that he recognised 1 Spillane JD. The doctrine of the nerves. Oxford: OUP not only the four ventricles, but also the secretory role 1981:41, 120, 138, 170-6. of the choroid plexuses and the circulation of CSF 2 Davidoff LM. Treatment of hydrocephalus. Historical the review and description of a new method. Arch Surg through 4th ventricle in the medulla, "through a 1929;18: 1737-62. cleft in its ceiling, between the pia and dura mater, and 3 Whytt R. Observations on the dropsy in the brain. Edinburgh; thence to the ". J Balfour, 1768.