Elicited repetitive daily blindness: a new phenotype associated with hemiplegic migraine and SCN1A mutations.

OBJECTIVE: Familial hemiplegic migraine (FHM) is a genetically heterogeneous disorder in which three genes, CACNA1A, ATP1A2, and SCN1A, are currently known to be involved. FHM is occasionally associated with other neurologic symptoms such as cerebellar ataxia or epileptic seizures. A unique eye phenotype of elicited repetitive daily blindness (ERDB) has also been reported to be cosegregating with FHM in a single Swiss family. METHODS: We report an additional family in whom the proband had, in addition to FHM, typical ERDB. In this family and the previously reported Swiss family, the whole coding region of the SCN1A gene was screened after exclusion of mutation in CACNA1A and ATP1A2 genes. RESULTS: We identified two novel SCN1A mutations (c.4495T>C/p.Phe1499Leu and c.4467G>C/p.Gln1489His missense substitutions) in exons 24 and 23, respectively, segregating with the disease in all living affected members. Both mutations were absent from 180 healthy Caucasian controls and were located in an intracellular loop highly conserved throughout evolution. CONCLUSION: We report new clinical data supporting cosegregation of familial hemiplegic migraine and the new eye phenotype of elicited repetitive daily blindness and two novel SCN1A mutations as the underlying genetic defect in two unrelated families. SCN1A encodes the voltage-gated sodium channel Nav1.1 that is highly expressed in the CNS including the retina. This remarkably stereotyped new eye phenotype has clinical characteristics of abnormal propagation of the retinal electrical signal that may be a retinal spreading depression. These results suggest that SCN1A mutations, which alter neuronal brain excitability, may occasionally alter retinal cell excitability.

Elicited repetitive daily blindness: a new familial disorder related to migraine and epilepsy.

The authors report a family affected by multiple daily episodes of transient visual loss, elicited repetitive daily blindness (ERDB); the onset was early in life, and the disease followed a benign course. ERDB is associated with childhood epilepsy and familial hemiplegic migraine, apparently segregating as a monogenic, autosomal dominant condition with variable expression. Genetic linkage to CACNA1A was excluded.

Acute bilateral carpal tunnel syndrome associated with human parvovirus B19 infection.

Human parvovirus B19 has been described as a causative agent of erythema infectiosum (a disease common in children), aplastic crisis in patients with hemolytic disorders, and arthralgias and arthritis. Joint involvement may be a prominent clinical feature of parvovirus B19 infection and may last for several weeks. We describe three cases of acute bilateral carpal tunnel syndrome associated with parvovirus B19 infection as evidenced by serological data and, in one case, by detection of parvovirus B19 DNA in blood with use of PCR.

[Wilson's disease: demonstration of lesions of the cortex and white matter by MRI]. / Maladie de Wilson: démonstration de lésions corticales et de la substance blanche par IRM.

Lesions of cortex and white matter are present in Wilson's disease in approximately 10 p. cent of cases. Before Magnetic Resonance Imaging (MRI) only post-mortem examination evidenced them. We report the case of a 15 year-old girl in whom Wilson's disease was diagnosed after partial motor epileptic seizures. She later presented with progressive extrapyramidal and pyramidal signs, severe cognitive weakening and disorder of behaviour. MRI clearly showed cortical and subcortical lesions by an enhanced signal (T2 values). It showed as well the classical picture of lesion in the lenticular nuclei. With T1 values it showed an extensive cortical atrophy and a widening of the ventricules.

[Post-radiation brachial plexopathy. Persistent conduction block. Myokymic discharges and cramps]. / Plexopathie brachiale post-radique. Blocs de conduction persistants. Décharges myokymiques et crampes.

The distinction between radiation and tumor brachial plexopathy may be difficult. The electrophysiological recording of myokymic discharges, frequently present in the former but rare in the latter type of plexopathy, can be helpful for the diagnosis. However, the pathophysiology and the site of origin of these discharges remain unclear. We describe a patient presenting with radiation brachial plexopathy, clinical myokymia, cramps and pain. In this patient, the myokymia--due to abundant myokymic discharges--and the cramps, were related to the existence of persistent conduction block of several years duration. Several findings suggest that the myokymic discharges were generated on blocked axons: voluntary activity did not influence their occurrence nor modify their course; the motor unit potentials involved in the discharges were not evoked by stimulation proximal to the site of the conduction block, whereas the stimulation distal to this site could evoke, modify the rhythm, or interrupt the course of the discharges; the latency of these evoked responses indicated that the site of reflection was proximal on the axon, and likely coincided with that of the conduction block. Recent observations (Roth and Magistris, 1987b) indicated that myokymia, produced by numerous single or grouped fasciculations generated on axon terminals, may be related to persistent conduction blocks of various etiologies. The present case demonstrates that myokymia provoked by myokymic discharges may as well be related to persistent conduction block. The reason why these blocks are accompanied by fasciculations in some situations and by myokymic discharges in others remains an unsolved question. The cramps observed in this patient were also of interest as they occurred in the muscle territory of blocked axons and were provoked by passive muscle shortening. Their origin, distal to the conduction block, is unknown. Finally, a neurolysis did not prevent the progressive transformation of conduction block into axonotmesis.