Hemifacial Spasm Associated With the Specific Offending Vein

Area of Science:

• Neurosurgery
• Neurology
• Vascular Anatomy

Background:

• Hemifacial spasm (HFS) is rarely caused by venous compression.
• Limited research exists on venous characteristics and pathogenic mechanisms in venous HFS.
• Understanding venous involvement may reduce surgical retreatment rates.

Purpose of the Study:

• To investigate the venous characteristics and pathogenic mechanisms of HFS caused by venous compression.
• To report successful microvascular decompression for HFS attributed to specific venous structures.

Main Methods:

• Presentation of 4 cases of HFS caused by the veins of the middle cerebellar peduncle (V. of Mid.Cer.Ped).
• Surgical intervention involved microvascular decompression.
• Intraoperative observations and abnormal muscle response (AMR) monitoring were utilized.

Main Results:

• V. of Mid.Cer.Ped were identified as the offending vessels in all cases.
• Veins coursed between facial and vestibulocochlear nerves, surrounding the facial nerve root ventrally.
• Successful decompression led to the disappearance of AMR and resolution of HFS symptoms without complications.

Conclusions:

• Veins can induce hemifacial spasm.
• The specific venous anatomy involves traversing between cranial nerves and surrounding the facial nerve root.
• Pulsatile cerebrospinal fluid dynamics contribute to nerve impingement and deformation.
• Intraoperative findings of venous compression on the facial nerve warrant consideration for venous decompression, even after arterial decompression, if AMR persists.