Etiology of Hemifacial Spasm

The facial nerve is inherently vulnerable at its exit point from the brainstem due to physiological reasons. If surrounding arteries become tortuous, elongated, or displaced—commonly as a result of arteriosclerosis—they may compress the nerve, leading to demyelination and subsequent disruption of neural conduction, thereby causing hemifacial spasm.

In simple terms, the nerve functions like an electrical wire; when a blood vessel “drapes over” the nerve, it causes a “short circuit,” resulting in abnormal signal transmission and formation of aberrant neural circuits—ultimately triggering facial spasm. How is hemifacial spasm treated? Since the underlying cause is vascular compression of the facial nerve leading to disrupted neural conduction, definitive treatment involves surgically separating the nerve from the offending vessel—thereby resolving the root cause of the condition.

Microvascular decompression (MVD) is a minimally invasive surgical procedure. A 4-cm incision is made behind the ear, and a bone opening approximately the size of a one-yuan coin is created in the skull. Through this small opening, the compressing vessel is carefully separated from the facial nerve. As neither the nerve nor the vessels are damaged during the procedure, no postoperative sequelae occur. Moreover, the incision lies within the hairline behind the ear, preserving cosmetic appearance. Female patients need only shave a palm-sized area of hair behind the ear; once their hair grows back, the surgical scar is completely concealed. The entire operation is performed under high-powered microscopic guidance, ensuring exceptional safety.