Microvascular surgery for trigeminal neuralgia

Trigeminal pain is described as sudden, severe, unilateral, brief, recurrent episodes of sharp shooting pain in the distribution of one or more of the trigeminal branches. The incidence is 5 in 100,000. Pain can be a sequel to normal stimuli such as eating or shaving. This pain is thought to be related to nerve compression by an artery or vein at the nerve dorsal root entry zone. In theory, the compression produces demyelination of nerve fibers, which can affect transmission, processing, and interpretation of impulses. The entry zone was first observed by Dandy in 1929. Later, NM Dott proposed demyelination at the entry zone as the cause of pain which Gardner described as a short circuit of afferent stimuli. In addition, King suggested a central mechanism for pain in the trigeminal distribution and Jannetta promoted microvascular decompression (MVD) as an effective treatment [1]. Left untreated, the patient with trigeminal neuralgia proceeds to have shorter intervals free of pain and may progress to have another more complicated type 2 pain syndrome. Patients who fail medical management either because of pain control or excessive side effects are candidates for surgical treatment. An extensive radiological exam may include reliable 3D high-resolution magnetic resonance imaging (MRI) with constructive interference in steady state (CISS) or fast imaging employing steady state acquisition sequence (FIESTA) that can identify the location and degree of compression at the entry zone. The clinical diagnosis combined with this expanded radiological exam will lead to better preoperative planning and an improved surgical outcome [2, 3].