[Vertebrobasilar abnormalities in patients with hemifacial spasm: MR-angiography findings]

Hemifacial spasm (HFS) is a disorder characterized by a complex of symptoms with hyperactive motor dysfunction of the facial nerve. It is indicated that HFS in the majority of cases can be caused by a blood vessel compressing the nerve adjacent to the brainstem.

We studied and treated 44 patients with HFS. Magnetic resonance imaging (MR) and MR-angiography of the brain were performed in patients with HFS to asses the presence of an artery of the vertebrobasilar system compressing the root of the facial nerve. We evaluate the response to treatment with Botulinum toxin in these cases. 14 patients were excluded (6 patients presented HFS due to other lesions and in 8 patients the MR was not performed). The remaining 30 patients with idiopathic HFS underwent MR/MRA (3D-FISP) and it was also performed in 14 patients with synkineses after facial palsy to be used as controls.

The MRA documented an abnormal position of the arteries surrounding the facial nerve (ipsilaterally to HFS) in 22 patients. The compressing artery was the PICA in 3 patients (10%), the AICA in 3 patients, the vertebral artery in 7 patients and the basilar artery in 8 patients, one patient showed a combined compression by AICA and PICA. The remaining 8 patients had a normal MRI. At the control group only one patient presented an abnormal AICA and the other had a normal MRI-MRA. Patients were followed-up for 22.4 months and after Botulinum toxin treatment patients kept 4.81 months free of symptoms.

We recommend to perform MR studies in all HFS patients to rule out a secondary cause of the disease and MRA to evaluate the underlying vertebrobasilar abnormalities if surgery is planned. Botulinum toxin is a useful treatment in these patients and only after its failure, microvascular decompression will be considered.