A comparison of quantitative sensory testing with skin biopsy in small fiber neuropathy

Patients with a small fiber neuropathy often are difficult to diagnose. They frequently undergo various diagnostic studies including quantitative sensory testing (QST) and skin biopsy. We wanted to determine if there was a correlation between findings on a QST study to that of a skin biopsy. Twenty patients were prospectively studied. Nine had an abnormal skin biopsy. Thirteen patients had an abnormal QST. Seven of the nine patients with an abnormal skin biopsy had an abnormal QST. Assuming that skin biopsy is the gold standard for identification of small fiber neuropathies, the sensitivity of QST for detection of such neuropathies is high, provided that both cold and warm sensation thresholds are studied. However, the specificity of QST for small fiber neuropathies is low (46%).