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.

The clinical and laboratory phenotype of a paraproteinaemic neuropathy syndrome termed chronic sensory ataxic neuropathy with anti-disialosyl IgM antibodies is described in a series of 18 cases. Previous single case reports have outlined some features of this syndrome. All 18 cases were defined by the presence of serum IgM antibodies which react principally with NeuAc (alpha2-8)NeuAc(alpha2-3)Gal-configured disialosyl epitopes common to many gangliosides including GDlb, GD3, GTlb and GQlb. In 17 out of 18 cases, the serum contained benign IgM paraproteins, and in four of these cases at least two IgM paraproteins were present. The IgM antibodies were also cold agglutinins in 50% of cases. The clinical picture comprised a chronic neuropathy with marked sensory ataxia and areflexia, and with relatively preserved motor function in the limbs. In addition, 16 out of 18 cases had motor weakness affecting oculomotor and bulbar muscles as fixed or as relapsing-remitting features. When present in their entirety, these clinical features have been described previously under the acronym CANOMAD: chronic ataxic neuropathy, ophthalmoplegia, IgM paraprotein, cold agglutinins and disialosyl antibodies. This distribution of clinical features is reminiscent of Miller Fisher syndrome, in which acute-phase anti-disialylated ganglioside IgG antibodies are found. Clinical electrophysiology and nerve biopsy show both demyelinating and axonal features. A partial response to intravenous immunoglobulin and other treatments is reported in some cases.

Aims/hypothesis: The early pathological features of human diabetic neuropathy are not clearly defined. Therefore we quantified nerve fibre and microvascular pathology in sural nerve biopsies from diabetic patients with minimal neuropathy. Methods: Twelve diabetic patients underwent detailed assessment of neuropathy and fascicular sural nerve biopsy at baseline, with repeat assessment of neuropathy 8.7±0.6 years later. Results: At baseline, neuropathic symptoms, neurological deficits, quantitative sensory testing, cardiac autonomic function and peripheral nerve electrophysiology showed minimal abnormality, which deteriorated at follow-up. Myelinated fibre density, fibre and axonal area, and g-ratio were normal but teased fibre studies showed paranodal abnormalities (p<0.001), segmental demyelination (p<0.01) and remyelination (p<0.01) without axonal degeneration. Unassociated Schwann cell profile density (p<0.04) and unmyelinated axon density (p<0.001) were increased and axon diameter was decreased (p<0.007). Endoneurial capillaries demonstrated basement membrane thickening (p<0.006), endothelial cell hyperplasia (p<0.004) and a reduction in luminal area (p<0.007). Conclusions/interpretation: The early pathological features of human diabetic neuropathy include an abnormality of the myelinated fibre Schwann cell and unmyelinated fibre degeneration with regeneration. These changes are accompanied by a significant endoneurial microangiopathy.