A new case of autosomal dominant myotonia associated with the V1589M missense mutation in the muscle sodium channel gene and its phenotypic classification.

We report a phenotype associated with the Val1589Met substitution in SCN4A gene in a French family which would be better classified as paramyotonia congenita. The proband was a 48-year-old woman, who described muscle stiffness and occasional flaccid weakness, both symptoms being induced by exercise, cold and heat. Severe muscle stiffness affected facial, oropharyngeal and limb muscles leading to transient paralysis of these muscles. One sister, two nephews and the son of the proband had similar symptoms. Molecular analysis of the muscle sodium channel gene (SCN4A) by nucleotide sequencing revealed a G-to-A transition of cDNA nucleotide at position 4765 predicting a substitution of methionine for valine at position 1589. This shows that the Val1589Met mutation in the SCN4 gene may cause different phenotypes, either potassium-aggravated myotonia or paramyotonia congenita. Familial or individual factors other than the missense mutation per se influence the expression of the disease in sodium channel disorders.

[Cortical blindness associated with Guillain-Barre syndrome: a complication of dysautonomia?]. / Cécité corticale associée à un syndrome de Guillain-Barré. Une complication de la dysautonomie?

INTRODUCTION: We report a case of a Guillain-Barre syndrome (GBS) with subarachnoid hemorrhage and regressive occipital white matter lesions. OBSERVATION: A 62-year-old woman developed ascendant progressive paresthesia and weakness of arms and legs, 48 hours after enteritis infection. Neurological examination showed tetraparesia with loss of deep tendon reflexes and alteration of proprioception tests. Nerve conduction studies revealed polyradiculoneuritis. Then she presented an acute blindness and hypertension. Brain magnetic resonance imaging showed bilateral occipital lesions and subarachnoid hemorrhage. Cerebrospinal fluid analysis revealed an elevated protein level (1.54 g/l) and red blood cells without meningitis. Brain arteriography was normal. Intravenous immunoglobulins improved neurological symptoms. CONCLUSION: Posterior localisation of reversible white matter lesions evoked a reversible posterior leukoencephalopathy. The implication of arterial hypertension caused by dysautonomia during GBS could be suspected.

A-delta and C-fibres function in primary restless legs syndrome.

STUDY AIMS: The sensory symptoms that are reported in restless legs syndrome (RLS) suggest involvement of the peripheral nervous system (PNS) in general and of the small-fibre system in particular. We aimed to study the status of the small-fibre system in primary RLS. PATIENTS AND METHODS: We investigated 10 patients with idiopathic RLS (mean time since disease onset: 11.4 +/- 12 years, mean International Restless Legs Syndrome Study Group [IRLSSG] score: 23.4 +/- 8). Five had a family history. All had normal results for laboratory tests, neurological examination, and a sural/deep-peroneal nerve conduction study. Lower-limb thulium YAG laser-evoked potentials (LEP) and skin sympathetic reflexes (SSR) were performed. The results were compared with data from 10 healthy subjects. RESULTS: The nociceptive thresholds were 293 +/- 62 mJ for patients and 333 +/- 77 mJ for controls. For patients, the vertex N2 and P2 latencies were 208 +/- 25 ms and 366 +/- 51 ms, respectively (controls: N2 = 235 +/- 41 ms; P2 = 373 +/- 44 ms). The N2-P2 amplitude was 19 +/- 6 microV for patients and 18 +/- 7 microV for controls. SSR were normal in all patients. No significant differences between patients and healthy subjects were observed. CONCLUSION: We failed to demonstrate any significant involvement of small fibres and spinothalamic tracts in idiopathic RLS. Even though sufferers of this specific form of RLS report sensory symptoms, pathogenesis appears to be dissociated from a PNS alteration.