Diabetic cervical radiculoplexus neuropathy: a distinct syndrome expanding the spectrum of diabetic radiculoplexus neuropathies

Diabetic lumbosacral radiculoplexus neuropathy is a subacute painful, asymmetrical lower limb neuropathy due to ischaemic injury and microvasculitis. The occurrence of a cervical diabetic radiculoplexus neuropathy has been postulated. Our objective was to characterize the clinical features and pathological alterations of diabetic cervical radiculoplexus neuropathy, to see if they are similar to diabetic lumbosacral radiculoplexus neuropathy and due to ischaemic injury and microvasculitis. We identified patients with diabetic cervical radiculoplexus neuropathy by review of the Mayo Clinic database from 1996 to 2008. We systematically reviewed the clinical features, laboratory studies, neurophysiological findings, neuroimaging and pathological features and compared the findings with a previously published diabetic lumbosacral radiculoplexus neuropathy cohort. Eighty-five patients (56 males, 67 with Type 2 diabetes mellitus) were identified. The median age was 62 years (range 32-83). The main presenting symptom was pain (53/85). At evaluation, weakness was the most common symptom (84/85), followed by pain (69/85) and numbness (56/85). Neuropathic deficits were moderate (median motor neuropathy impairment score 10.0 points) and improved at follow-up. Upper, middle and lower brachial plexus segments were involved equally and pan-plexopathy was not unusual (25/85). Over half of patients (44/85) had at least one additional body region affected (30 contralateral cervical, 20 lumbosacral and 16 thoracic) as is found in diabetic lumbosacral radiculoplexus neuropathy. Recurrent disease occurred in 18/85. Neurophysiology showed axonal neuropathy (80/80) with paraspinal denervation (21/65), and abnormal autonomic (23/24) and sensory testing (10/13). Cerebrospinal fluid protein was elevated (median 70 mg/dl). Magnetic resonance imaging showed brachial plexus abnormality in all (38/38). Nerve biopsies (11 upper and 11 lower limbs) showed ischaemic injury (axonal degeneration, multifocal fibre loss 15/22, focal perineurial thickening 16/22, injury neuroma 5/22) and increased inflammation (epineural perivascular inflammation 22/22, haemosiderin deposition 6/22, vessel wall inflammation 14/22 and microvasculitis 5/22). We therefore conclude that (i) diabetic cervical radiculoplexus neuropathy is a predominantly monophasic, upper limb diabetic neuropathy with pain followed by weakness and involves motor, sensory and autonomic fibres; (ii) the neuropathy begins focally and often evolves into a multifocal or bilateral condition; (iii) the pathology of diabetic cervical radiculoplexus neuropathy demonstrates ischaemic injury often from microvasculitis; and (iv) diabetic cervical radiculoplexus neuropathy shares many of the clinical and pathological features of diabetic lumbosacral radiculoplexus neuropathy, providing evidence that these conditions are best categorized together within the spectrum of diabetic radiculoplexus neuropathies.