P. K. Thomas

Observations have been made on a series of 228 patients with hereditary motor and sensory neuropathy, comprising 120 index cases and 108 affected relatives. These could be separated into genetically distinct type I and type II categories depending upon whether motor nerve conduction velocity in the median nerve was below or above 38 m s-1. These disorders constitute separate genetic subgroups within the clinical spectrum of 'peroneal muscular atrophy'. Type I cases were more numerous. Most were of autosomal dominant inheritance, but a proportion were sporadic. Four families with probable autosomal recessive inheritance were identified; these displayed significantly slower motor conduction velocity. There was a positive correlation between motor conduction velocity in the propositi and that in their relatives in the total type I group which persisted after the autosomal recessive cases had been extracted, indicating further genetic heterogeneity amongst the autosomal dominant families. No X-linked recessive families were encountered. Type I cases had a peak age of onset of symptoms during the first decade of life. In comparison with the type II cases, they displayed a greater tendency to show weakness of the hands, upper limb tremor and ataxia, generalized tendon areflexia and more extensive distal sensory loss, sometimes with acrodystrophic changes. Foot and spinal deformities were more frequent, probably due to the earlier age of onset. Nerve thickening was confined to the type I cases. The onset of symptoms was most often in the second decade in the type II cases, but in some it was delayed, even as late as the seventh decade. Most cases were again of autosomal dominant inheritance, but two probable autosomal recessive families were detected, as well as sporadic cases. Upper limb tremor also occurred in this form but was considerably less common. In both types, males tended to be more severely affected, and asymptomatic affected family members ('formes frustes') were more commonly female.

Observations have been made on nine cases of painful diabetic neuropathy of acute onset. All cases were male and all were associated with and preceded by precipitous and severe weight loss. The pain was of a continuous burning quality and experienced mainly in the legs, especially distally. Contact discomfort of the skin was often a troublesome feature, but sensory loss was mild or absent, and reflex loss or depression not invariable. There were no accompanying motor signs. Depression and impotence were constant features. The weight loss responded to adequate control of the diabetes with insulin and was followed by improvement in the neuropathy. The severe manifestations subsided in all cases within 10 months, and in most cases within 6 months, and later resolved completely in all except one. No recurrences were observed after follow-up periods of up to 6 years. Abnormalities of nerve conduction were mild or even lacking. Sural nerve biopsies from three cases taken in the acute stage showed evidence of active degeneration of myelinated nerve fibres of all diameters and also degeneration of unmyelinated axons. There was a mild degree of demyelination. It is concluded that acute painful diabetic neuropathy is a distinct syndrome, occurring in insulin or noninsulin dependent patients of any duration, and unrelated to other diabetic complications. It is separable from other types of painful diabetic sensory polyneuropathy that have been described.

Clinical and electrophysiological investigations and nerve biopsies were carried out on 61 patients shown to have a chromosome 17p11.2 duplication (hereditary motor and sensory neuropathy-HMSN Ia). Of these, 50 showed a Charcot-Marie-Tooth (CMT) phenotype and eight could be classified as having the Roussy-Lévy syndrome. Of the patients with a CMT phenotype, three had associated pyramidal signs and of these one had 'complicated' HMSN and also signs of cerebellar and bulbar involvement. Diaphragmatic weakness was present in three severely affected cases, one of whom also had denervation of the anal sphincter associated with faecal incontinence. One unusual case presented in middle life with incapacitating muscle cramps associated with calf hypertrophy and only mild clinical signs of neuropathy. Prominent distal sensory loss was a consistent feature in one family, resulting in acrodystrophic changes in several members. Concurrent focal peripheral nerve lesions were seen with both the CMT and Roussy-Lévy phenotypes, in seven patients. Upper limb motor nerve conduction velocity was 19.9 m/s +/- 1.3 (SEM), range 5-34 m/s. This corresponds to values previously obtained for autosomal dominant HMSN I. This series consisted mainly of older patients with more advanced disease. In contrast to the findings in younger patients, in their nerve biopsies, myelin thickness tended to be relatively reduced for axon size, indicating remyelination and/or hypomyelination; there was also regression of the onion bulbs. It is concluded that the possession of two copies of the peripheral myelin protein 22 gene within the duplicated region on chromosome 17p gives rise to a range of phenotypes and not solely to a CMT syndrome, and that the pattern of histological change in the peripheral nerves alters with advance of the disease.