engleski

Pathological Studies in Diabetic Amyotrophy

The aetiology of diabetic amyotrophy is unclear. A vasculitis aetilology has been proposed. We have studied 10 Type II diabetic patients (Age 65, 4+/-7, 2 yr, duration of diabetes- 10, 2 +/- 7, 6 yr., duration of amyotrophy- 4, 2 +/- 1, 8 months, HbA1c- 7, 7 +/- 1, 3%) with this condition. Proximal femoral nerve conduction velocity (FNCV) (39, 3 +/- 8, 4 ms -1) and distal sural nerve conduction velocity (SNCV) were (35, 8 +/- 4, 9 ms -1) reduced when compared to our matched diabetic patients with equivalent distal neuropathy without amyotrophy (FNCV- 60 +/- 5, SNCV- 38 +/- 5) and normal control range (FNCV- 70 +/- 5, SNCV- 50 +/- 5 (ms -1). Each patient underwent biopsy of the Intermediate cutaneous nerve of the thigh (FN) and sural nerve (SN). The sural nerve was also biopsied from 8 control subjects and detailed morphological analysis of the myelinated fibres was undertaken. Myelinated fibre density (no.mm -2) was uniformly and signifantly reduced in FN (3104 +/- 181, P<0, 0004) and SN (2756 +/- 454, P<0, 0009) compared to control subjects (6561 +/- 407). Myelinated fibre area (um 2) did not differ significantly between FN (27, 7 +/- 2, 4) and SN (28, 9 +/- 2, 2) v control (29, 1 +/-1, 6). However, myelinated fibre axonal area (um 2) was significantly reduced in the FN (5, 9 +/- 0, 4, P<0, 0001) and SN (7, 1 +/- 0, 3, P<0, 0008) v controls (10, 5 +/- 0, 8) and the g-ratio was significantly reduced in the FN (0, 21 +/- 0, 01, P<0, 0001) and SN (0, 25 +/- 0, 02, P<0, 0008) v controls (0, 36 +/- 0, 2). Diabetic amyotrophy is characterised by a marked reduction in proximal femoral nerve conduction velocity far greater than diabetic patients matched for distal neuropathic severity. The underlying pathology is that of a proximodistal loss of myelinated fibres and axonal atrophy. The neuropathological changes were nog consistent with acute multifocal fibre loss and a mild perivasculitis was noted in only one FN biopsy questioning the role of vasculitis in the pathogenesis of the condition.

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