Whilst peripheral sensory neuropathy is the modality tested for when screening for the “at risk” foot, motor and autonomic neuropathy also frequently co-exist in the neuropathic foot. Sensory neuropathy allows the patient to traumatise the foot without being aware, whilst motor neuropathy leads to muscle atrophy, foot deformity, and altered pressure distribution across the foot predisposing the foot to ulceration. Autonomic neuropathy can lead to altered regulation of cutaneous blood flow, loss of sweating and hence dry fragile skin, prone to cracking, fissures and infection.
Painful peripheral neuropathy occurs in about a third of patients with peripheral neuropathy and may exist in the absence of any signs of motor or sensory neuropathy. Patients complain of burning, tingling, aching or stabbing pains, or feet feeling abnormally hot or cold. Patient often have difficulty understanding that painful neuropathy may co-exist with sensory neuropathy, putting them at risk of trauma even though they perceive that they can feel their feet because they are experiencing pain. Patients’ misperceptions about
Figure 5.1 Testing for neuropathy using a Semmes Weinstein Monofilament giving standard 10 g of fine touch
Neuropathy have been shown to have a negative impact on the kind of self-care behaviour that may prevent foot ulceration and careful explanation about the nature of the pain is required.