History
Clinical assessment of the patient with suspected peripheral neuropathy should include careful review of the past medical history, with attention to systemic diseases that can be associated with peripheral neuropathy, such as diabetes and hypothyroidism.
Many medications can also cause a peripheral neuropathy. These include nitrous oxide, colchicine, metronidazole, lithium, phenytoin, cimetidine, disulfiram, chloroquine, amitriptyline, thalidomide, cisplatin, pyridoxine, and paclitaxel. Conditions that are related to these drugs typically involve distal symmetric sensorimotor neuropathy. Any patient drug or alcohol use or exposure to solvents and heavy metals should be investigated.
Patients should also be questioned about their exposure to the human immunodeficiency virus (HIV), vitamin use, Lyme disease, and foreign travel (ie, exposure to leprosy). A family history that demonstrates the familial presence of hammer toes, cavus foot, gait abnormalities, and muscle weakness may indicate a long-standing or familial neuropathy.
Physical Examination
Patients typically present with vague symptoms of foot pain, which can sometimes be confused with plantar fasciitis. Findings of tenderness over the nerve, paresthesias, and numbness of the foot in the distribution of the tibial nerve are not uncommon. In some cases, atrophy of the intrinsic foot muscles may be noted, although this may be clinically difficult to ascertain. Eversion and dorsiflexion may cause symptoms to increase at the endpoint range of motion.
The Tinel sign (gentle tapping or percussion over the nerve causing radiation of pain and paresthesias along its course) may often be induced posterior to the medial malleolus. Symptoms generally subside with rest, though they typically do not disappear rapidly or altogether. (The Tinel sign, which is percussion of a nerve with a resultant distal manifestation of paresthesias, should not be confused with the Phalen sign, which is compression of the suspected nerve for 30 seconds, with subsequent reproduction of the patient's symptoms.)
Physical examination may demonstrate reduced sensitivity to light touch, pinprick, and temperature in patients with distal symmetric sensorimotor neuropathy.
Radiographic examination of the patient's limbs may demonstrate loss of bone density, thinning of the phalanges, or evidence of neuroarthropathy (eg, Charcot disease) in long-standing neuropathies. Additionally, trophic changes may include pes cavus, loss of hair, and ulceration. These findings are most prominent in those with diabetes, amyloid neuropathy, leprosy, or hereditary motor sensory neuropathy (HMSN) with prominent sensory involvement. Perineural thickening may be noted in cases of leprosy and amyloid neuropathy.
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Surgical approach for release of flexor retinaculum in patient with tarsal tunnel syndrome.
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View of tibial nerve after division of flexor retinaculum.
