Orofacial and somatic somatosensory evoked potentials in the diagnosis of neuropathy in patients with Sjögren's syndrome. We sought to assess the orofacial somatosensory evoked potentials (SSEPs) in the diagnosis of neuropathy in patients with Sjögren's syndrome (SS). The study group comprised 20 patients with SS (seven with definite, five with probable, and eight with possible SS). We recorded somatosensory evoked potentials (SSEPs) by stimulating the tibial nerve at the ankle (distal) and at the foot (proximal) and recorded the corresponding orofacial (OFSSEPs) from the temporal region and facial muscles. A total of 15 controls without neurogenic disorder were studied. Three patients (two probable and one definite SS) had large amplitude potentials, and two patients with definite SS had normal OFSSEPs. None of these were positive for antinuclear antibodies. Although none of the patients had clinical sensory neuropathy, electrophysiologic studies showed abnormalities in 12 patients (seven definite, four probable, and one possible SS). Four of the 12 patients with electrophysiologic abnormalities had no clinical sensory neuropathy and one had pure motor neuropathy. Abnormal facial nerve function (facial palsy) was found in five patients (two definite, one probable, and two possible SS). Electrophysiologic abnormalities correlated only with the presence of antinuclear antibodies. Neither a sensory deficit nor a motor deficit nor facial palsy distinguished the patients with electrophysiologic abnormalities from those without such abnormalities. OFSSEPs are abnormal in a substantial number of SS patients. OFSSEPs show an increased excitability or hyperexcitability of the CNS or changes in its conduction speed. The electrophysiologic abnormalities found in SS are very probably due to changes in the small fiber peripheral nerve. These abnormalities do not necessarily parallel the presence of a neuropathy. Their existence in the absence of clinical neuropathy, in the majority of the patients, suggests that these patients could be at high risk for the development of peripheral neuropathy. However, a large proportion of SS patients do not show electrophysiologic evidence of neuropathy, and the reason for this remains unclear.