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short recovery period the patient can go home. The patient may have numbness, temporary jaw weakness, dizziness, intermittent feelings of crawling in the face, slowing of the heart rate or increased blood pressure during the procedure, cold sores, ear pain, jaw pain or a small blood clot. More severe complications include meningitis and nerve paralysis.
MVD OPERATIVE TECHNIQUE
The role of surgery should be complete pain relief and is the procedure of choice for trigeminal neuralgia failing other therapy. The goal of surgery is, through a limited opening in the posterior fossa, using skull base microneurosurgical techniques, identify the vascular compression at the root entry zone and displace it. Once again the patient should have failed medical treatment and accept the risks of the operation. These risks include those for balloon compression as well as large blood clot requiring an emergent brain operation, stroke, deafness, double vision, CSF leak, seizures, injury to the cerebellum and death.
Under general endotracheal anesthesia, utilizing brain stem auditory evoked responses and masseter EMG, the patient is placed under general anesthesia in the lateral position. The body is then taped extensively to hold the position, to maintain the shoulder out of the way and to hold the ear anterior. The head is placed in three point fixation, head turned 10 degrees, vertex down 10 degrees and flexed 20 degrees, to provide a 45 degree angle with the microscope and at the same time allowing gravity to retract the cerebellum. At the intended incision line a minimum amount of hair should be shaved. Antibiotics are given, steroids are optional.
The skull base neurosurgeon makes a relaxed "S" incision that is intended to be centered over the junction of the transverse and sigmoid sinus, extending from 1.5 cm posterior to the mastoid tip to just below the tip of the pinna of the ear, slightly off the vertical axis. This may be minimally larger in individuals with thick musculature.
The incision occurs in two layers, the first to the galea and the second slightly displaced, down to the pericranium. This allows for a more water- tight closure. Small self- retaining retractors are brought into place. The craniotomy opening is then fashioned with a high -speed drill; its exact location determines its size. It is possible to construct a "dime size" (17 mm) or "quarter size" (24 mm) hole. The site of the craniotomy can be determined with a stereotactic system or using anatomical landmarks. If the occipital bone is thick or well rounded then the craniotomy will likely need to be a "quarter size" because of the angle needed for intracranial exposure. It is this minimal resection of bone in the optimal location that allows neurosurgery with the least complications, operating in the angle between the tentorial covering of the posterior fossa and the it's lateral bony border the petrous ridge. However, the surgery should NEVER be a struggle. The dura is opened; the edges are tacked back over the sinus, retracting the sinuses without occlusion. At this point the exposure MUST include the tentorium petrous angle not just the cerebellum. If the angle is not seen the opening must be made larger, retracting the cerebellum out of the way to access the angle is not an option. The microscope is brought in as soon as the dura is opened. Wet telfa protects the cerebellum as malleable retractor is advanced in the tentorial petrous angle at the superior lateral cerebellum, under direct visualization, allowing the recognition and opening of the arachnoid. CSF should be drained as much as possible. There are occasional veins from the cerebellum to the tentorium (Continued on page 49)
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