Common and Less Common Peripheral Nerve Disorders Associated with Diabetes

Diabetes can be associated with a number of peripheral nerve disorders. The commonest is slowly-progressive axonal distal symmetrical sensori-motor neuropathy. Sensory loss and positive sensory symptoms are its main manifestations. Lumbosacral radiculoplexus neuropathy (LSRPN) is a distinct entity, accompanied by severe lumbar, hip, leg pain and weight loss, with subsequent weakness. Although typically unilateral, bilaterality is described, with spontaneous recovery usual over several months. The upper limb counterpart, cervical radiculoplexus neuropathy is rare. Acute painful neuropathies, including “diabetic neuropathic cachexia”, are infrequent. Accompanying weight loss is usual and burning pains in the extremities are severe. Insulin-triggered acute painful neuropathy is well-described although infrequent and still poorly-understood. Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) represents an immunemediated treatable disorder, usually causing prominent diffuse motor weakness, which was described as more common in diabetics. More recent epidemiological data have however been conflicting and it is possible that CIDP is no more frequent in diabetics than in the general population. Diagnosis is made by electrophysiology and cerebrospinal fluid analysis. A painless diabetic motor neuropathy, thought to be caused by ischaemic injury and microvasculitis, has recently been postulated as separate from LSRPN and CIDP. Other focal and multifocal neuropathies that can occur in diabetics are cranial or truncal. Entrapment neuropathies are more often of median and ulnar nerves, and may in some cases benefit from decompression. Finally, autonomic neuropathies are well-described in diabetes and can be diverse in presentation with cardiovascular, gastrointestinal, urogenital and sudomotor manifestations. Their management can be difficult with debilitating symptoms despite treatment.