Magnetic resonance tomographic angiography in the investigation of hemifacial spasm.

Magnetic resonance angiography (MRA), combined with submillimeter magnetic resonance tomographic angiographic sections (MRTA) showed vascular compression of the 7th cranial nerve or its root exit zone (REZ) in the brain stem in 24 of 37 patients (64.86%) with hemifacial spasm. MRA alone was positive for REZ compression in only 19 (51.4%) cases, while conventional MRI was even less revealing, only 10 (27%) cases being positive.