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Show urU~ArUR[ ABSTRACTS Eight patients with clinical features of myastlwnia gravis, in whom no serum antibody against ,H:l'tykhlliine receptor nluld Ill' dl'teded, were sho~Yn tll h,lVl' ,1 Illv,lstlll'nic disorder that is c.Hlsed bv ,1ntibodies 1'0 dl'lermin,lnts ,1t the neuroIlluscul,; r junctil1ns otlll'r than thl' antibodil's ,1g,linst ,lCl'lvlcholine receptor. These patients pril11. uilv il',ltured Wl',lklll'SS of bulbar, rl'spiratory, lH lll:ubr l11uscll's. TIll' my,lsthenic kature of thymic hyperpl,lSi,l W,lS ,1bsent in thl' two patients wilo unl1erwent thVIl1l'ctllmy before immunosup- . . pressive drug treatment was started. This obser-vatil) n raises the question of whether thymectomy is 'lppropriate in this group of patients, considering that in some (but not all) reports the response tll thymectomy is positively correlated with the degree of hyperplasia in the thymus. Precise site of action at the neuromuscular junction of these patients' antibodies still needs to be defined. In addition, therapeutic means for treating this type of myasthenia were felt to need further evaluation. Api/lOalll B. Safral/, M.D. Optic Neuropathy and Chronic Cyanide Toxicity (letter). Freeman AG. Lancet 1986;1:441-2 (Feb). [Reprint requests to Anthony G. Freeman, Meadow Rise, 3, Lake Side, Swindon, Wiltshire SN3 IQE, England.] Incidence of chronic cyanide neurotoxicity rose sharply among people who, in the 1969 Nigeria civil war, fled into the bush and lived on uncooked and unprepared cassava roots and leaves. A similar phenomenon was also reported in Mozambique in 1981. Clinical features included bilateral optic neuropathy and nerve deafness, myopathy, and sensory ataxia. A rise in plasma cvanocobalamin levels and in plasma and urin~ry thiocyanate levels was found (i.e., product of cyanide detoxification). This supported the assumption that the dietary source of cyanide in cassava and in other vegetables contributed to the pathogenesis of these neurological manifestations of chronic cyanide toxicity. AlJil/oalll B. Safran, M.D. Parkinsonism, Tardive Dyskinesia, Akathisia, and Depression Induced by F1unarizine. Chouza I Clill Neuro'ophtllCllmo/, Vol. b, No.4, 1986 C, Scaramelli A, Caamano JL, De Medina 0, AIjanati R, Romero S. Lancet 1986;1:1303-4 Oun). IReprint requests to C. Chouza, Instituto de Neurologia, Hospital de C1inicas, Montevideo, Uru-guayl · Administration of flunarizine was observed to induce extrapyramidal motor signs, including orofacial tardive diskinesia, in 12 subjects. One affected wuman still presented symptoms 20 months after stopping flunarizine, while other patients showed partial or complete improvement after withdrawal of the drug. Flunarizine is a calcium- entry blocker, and is widely prescribed for a number of conditions, including cerebral bloodflow disturbances, migraine prophylaxis, and epileptiC seizures. Flunarizine has a piperazine radical that links it to neuroleptics and antihistamics, and it is conceivable that side effects may be related to the blockade of postsynaptic dopaminergic receptors b~' f1unarizine. Al'inoalll B. Safran, M.D. Detection of Optic Nerve Lesions in Optic Neuritis with Magnetic Resonance Imaging (letter). Miller DH, Johnson G, McDonald WI, MacManus D, DuBoulay EPGH, Kendall BE, Moseley IF. Lane!'! 1986;1:1490-1 Oun). [Reprint requests to D. H. Miller, Institute of Neurology, London WCl, England.) In most sequences of magnetic resonance imaging (MRI), orbital images are dominated by the signal arising from orbital fat. Using an inve~sion recovery sequence with a short inversion time of 100-150 ms (STIR sequence) allows us to obtain images in which orbital fat gives little signal, and other orbital structures, including optic nerve and extraocular muscles, are highlighted against the fat. In turn, demyelinated plaques, with long T1 relaxation times, should provide a higher signal than normal optic nerve when using this sequence. Eighteen patients with optic neuritis and 15 controls were scanned (using the STIR technique) on a Picker 0.5 T superconducting system. A surtace coil specially designed for orbital imaging was used to obtain 5-mm coronal and longitudinal slices. Ten of 14 patients who presented WIth an acute unilateral optic neuritis 18 n:onths be~ore the examination showed a high SIgnal area m the appropriate optic nerve. Four pa- |
