Diabetes vignette. Weak left hand – query stroke in a diabetic double amputee

Abstract

The patient was a 75-year-old bilateral amputee with insulin-treated type 2 diabetes, hypertension and dyslipidaemia controlled on treatment, and peripheral vascular disease treated with aspirin. He was admitted having fallen while transferring from wheelchair to bed; this was a simple fall and he had normal glucose and blood pressure levels. He was an ex-smoker, but his chest X-ray was normal. He was very rapidly back to his pre-admission state and abilities. On the ward he was mobile unaided in his wheelchair, administering his own insulin; he enjoyed zipping along the smooth hospital corridors and going to the local pub either with permission and a member of staff, or with neither, but only ever drank 1 or 2 pints. A seminal paper on outcomes post amputation stated that only 5% of amputees rehabilitated well, to become independent of their wheelchair, and that more consideration should be given to surgery that optimised wheelchair rehabilitation;1 our patient was an excellent example of someone who was very able in a wheelchair. He was a bit of a rascal who spoke his mind; thus, he remained in hospital for four weeks with ongoing negotiations about returning home to his very sheltered residence who had a ‘can't do’ mentality. During his hospital stay, he developed a weak left hand (see Figure 1); stroke was diagnosed and CT scan brain showed an old small infarct in the cerebellum, but was otherwise normal. On careful examination he had a wrist drop with weak wrist and finger extension (0/5 MRC power scale) but wrist and finger flexion, and finger abduction and adduction were normal; there was numbness on the dorso-radial aspect of the hand. When examining a hand with wrist drop, it is important to support the hand in its neutral position to allow the intrinsic hand muscles (innervated by ulnar and median nerves) to not work at a disadvantage, otherwise these muscles may appear weak. It is well recognised that several entrapment neuropathies are associated with diabetes such as median, ulnar, and lateral popliteal nerves, and lateral cutaneous nerve of thigh;2 however, data on an association between radial nerve palsy and diabetes are scarce, despite the evidence that the nerves of people with diabetes are more prone to compression neuropathies.3 A leading textbook states that radial nerve palsy is not related to diabetes, but a pressure palsy had been seen following hypoglycaemic unconsciousness.4 However, Stamboulis and colleagues reviewed patients with focal neuropathies referred for nerve conduction studies; the prevalence of known diabetes in people with radial nerve palsies was 28% versus a local population prevalence of known diabetes of 7%.5 Causes of radial nerve palsy include fractured neck of humerus, gunshot wounds, and lying on the nerve due to decreased consciousness;6 none of these applied to our patient who never returned from the pub drunk, and whose blood glucose monitoring was consistently in the 5–10mmol/L range. In most wheelchair users, the weight of their two legs prevents the wheelchair from tipping over backwards. But this is a problem for double amputees; hence for double amputees, including our patient, the wheelchair rear wheels are moved further back7 to regain balance. It was noticed that as the patient was zooming around the hospital, he would move his arms far back for rapid self-propulsion and catch the inner upper arm on the wheelchair handles; this seemed the likely cause of his neuropraxia. Standard treatment of compression radial nerve palsy is to splint the wrist to allow the hand muscles to function with a good grip,6 and wait and see; this was done as well as advice to slow down. After one week, the wrist drop was markedly improved; radial nerve compression palsies are generally neuropraxic and resolve within one week. Unfortunately, one month after discharge the patient died suddenly, presumably from cardiovascular causes, exemplifying the high mortality rate of amputees.1 Accurate clinical skills and knowledge are important to avoid unnecessary consultations and investigations, particularly in these times of coronavirus pandemic. Alternatively, if one practises using pattern recognition, this just looks like a radial wrist drop.