This case is a good example of the need to evaluate whether the previous approach offered the best exposure to the tumor. The midline approach does not offer adequate midline exposure of the tumor. Associated neural structures can be injured when they are retracted during this approach. The use of muslin and the associated scarring illustrate complications that can change or increase the difficulty of a reoperatton. The patient also had a previous postoperative pseudo-meningocele. Direct closure was attempted but failed. It eventually required a lumboperitoneal shunt.

 

　　The displacement of the brain stem and upper cervical cord to the right mandated an approach from the left. The far-lateral transcondylar approach offered a fresh exposure to the tumor. The patient was placed in the modified park bench position. An inverted hockey stick incision incorporated the previous midline incision but circled laterally to the mastoid tip.The scalp flap was dissected from the scar tissue in the midline and reflected posterolaterally to expose the left side of the previous operative approach. This maneuver provided access to the lateral posterior fossa. The posterior fossa craniectomy was expanded laterally to the occipital condyle and through the inferior mastoid  region.   The posterolateral condyle and the lateral mass of Cl were drilled away.

 

　　Only remnants of dura were in the previous operative site, but clean dura was found along the lateral aspect of the expanded bony exposure. The intact dura was open and reflected laterally. Under the operating microscope,  the lower cranial nerves were identified from the jugular foramen and the hypoglossal c** and traced toward the brain stem. The vertebral artery and cranialnerves were carefully microdissected from the scar tissue. The hard, calcified mass of muslin encasing the vertebral artery was dissected free from the vertebral artery and brain stem and removed. The tumor was therefore exposed without retracting the brain stem.  This maneuver was important because the brain stem had extensive arachnoid scarring.   Retraction without removal of these adhesions could have damaged the brain stem.

 

　　For complete tumor excision, these adhesions were taken down with sharp dissection,  and the dentate ligaments of the upper cervical cord were cut to allow mobilization.Once mobilized and fully exposed, the tumor was removed completely to prevent the recurrence of a pseudomeningocele.a fascial graft was used to close the operative site. Nonetheless, a pseudomeningocele recurred and required a ventricular peritoneal shunt. The lumbar peritoneal shunt system did not function properly because of extensive neurofibromas of the cauda equina. Postoperatlvely,  the patient's quad**aresis improved and she had no new neurologic deficits.

 

　　Case 22: Petroclival meningioma

 

　　岩斜脑膜瘤

 

　　A 49-year-old female presented with a 1-year history of stag-g and poor balance, a several year history of occasional nau-sea and vomiting, and a 10-15-year history of night terrors and sleep-walking. Several years prior to her admission, she was medically treated for trigeminal neuralgia on the left side, which sided without recurrence.  Her neurological exam was significant for left cerebellar signs,as well as a positive Rhomberg with the patient falling to the left. An audlogram showed bilateral high-frequency hearing loss.Both CT and MRI demonstrated a large petroclival tumor with extensions through the tentorial hiatus. A cerebral arteriogram showed that the sinuses were patent. Using the petrosal approach, we gained access to and totally removed the meningioma. Her postoperative course was uneventful with the patient neurologically intact aside from the cerebellar signs present preoperatlvely, which gradually resolved over 1 month. On follow-up after 2 weeks? the patient demonstrated a large CSF collection under the skin flap.This was successfully treated with spinal drainage.   There has been no sign of tumor recurrence after 4 years of follow-up.

 

　　Case 23: Petroclival middle fossa meningioma

 

　　岩斜中颅窝脑膜瘤

 

　　This 45-year-old woman was evaluated 8 years previously for Meniere's disease. She presented now with a complete hearing loss on the left and vertigo. CT and MRI scans revealed a tumor involving the petrous ridge, tentorium, and the middle cranial fossa on soft tissue windows, and the petrous bone. During an initial operation,  meningioma was removed from the posterior and middle fossae. Residual tumor was present in the internal auditory c**,  the petrous bone, Meckel’s cave, and the clival dura a-round CN VI.  During a second operation 9 days later, a subtotal piecemeal petrosectomy with the removal of all residual tumor was performed.CN Ⅶ was tumor encased in the intrac**icular, labyrinthine, and tympanic segments. Resection of the epineurium allowed the nerve to be preserved. The patient sustained a temporary palsy of CNs V[ and Vtt postoperatively.The patient developed a necrosis of the posterior edge of the very thin scalp flap. This required debridement and a trapezius muscle rotation flap. The abducens palsy resolved quickly, and the facial nerve palsy improved over 5 months, eventually with House grade n function. No tumor recurrence was noted a year later.

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