Secretion of tears in patients with hemifacial spasm

Hemifacial spasm can cause abnormal tear secretion on the affected side. Thirty patients with this disease were examined using the Schirmer's test without topical anesthetic. Twelve of them showed more tear secretion on the affected side than on the unaffected side. The average Schirmer test value was 30.4 +/- 12.3 mm (+/- SD) on the affected side in the patients and 17.4 +/- 10.9 mm (n = 148) in the control subjects (P less than 0.001). Microvascular decompression surgery reduced the hypersecretion of tears. The results suggest that compression of the facial nerve by a blood vessel causes an excitatory stimulus for tear secretion in patients with hemifacial spasm.