Rudy Bilous, MD, FRCP
Richard Donnelly, MD, PHD, FRCP, FRACP
Symptoms, signs and classification
Diabetes is one of the most common causes of peripheral neuropathy, a term that encompasses a heterogeneous group of disorders (Figure 17.1). In population-based surveys, up to one-third of patients with diabetes have evidence of peripheral neuropathy but many are asymptomatic. Diabetic neuropathy should not be diagnosed solely on the basis of one symptom, physical sign or test; it is recommended that a minimum of two abnormalities be detected (symptoms, signs or test abnormalities – nerve conduction, quantitative sensory testing or quantitative autonomic testing) (Box 17.1)….
Chronic sensorimotor neuropathy
Chronic sensorimotor neuropathy is the most common form of diabetic neuropathy. This results from the distal dying back of axons that begins in the longest nerves; thus, the feet are affected first in a stocking distribution, and later there may be progressive involvement of the upper limbs. Sensory loss is most evident; autonomic involvement is usual, although it is mostly symptomless. Positive painful symptoms tend to be worse at night. Neurological examination shows a symmetrical sensory loss to all modalities, reduced or absent ankle or knee reflexes, and small muscle wasting of the feet and hands (Figure 17.3). The foot at high risk of neuropathic ulceration might have a high arch (pes cavus deformity) and clawing of the toes.
A simple staging system has been developed for diabetic neuropathy (Box 17.2).