Faculty Bibliography

BACKGROUND: In this article, we report on the technique of placing fat in between a sellar or parasellar neoplasm and the optic chiasm to possibly protect the optic chiasm from sequelae of radiation. METHODS: A review was performed on three patients, each of whom had planned subtotal resection with fat placed near their optic chiasm to facilitate future radiosurgery. RESULTS: Follow-up on our three patients varied from 6 months to 3 years post-stereotactic radiosurgery. The fat remained stable and in place. The tumors either remained stable or reduced in size. No infections, postoperative marker dependent neurological complications or unusual symptoms were encountered. CONCLUSIONS: Placement of fat between a parasellar neoplasm and the optic chiasm appears to be a safe approach to help define the tumor chiasm space, helping to facilitate radiosurgery. Future experience is warranted to determine the efficacy of this technique.

A petroclival meningioma represents a challenging tumor to resect in the cerebellopontine angle and ventral to the brain stem. Multiple cranial nerves and blood vessels may be intimately involved with the tumor. A partial labyrinthectomy presigmoid transpetrosal approach can facilitate resection while preserving hearing. This approach allows for a direct line of sight along the petrous bone while sealing the canals can preserve hearing. In this video operative manuscript, we demonstrate a step-by-step illustration of a partial labyrinthectomy presigmoid transpetrosal resection of a petroclival meningioma. This approach affords the best chance of hearing preservation and an opportunity for maximum tumor resection. The video can be found here: http://youtu.be/29I4KEXz1vY .

Cervical radiculopathy secondary to compression from congenital anomalous vertebral arteries (VAs) is a known entity. Patients present with a variety of symptoms ranging from upper-extremity numbness to true occipital neuralgia. Treatment options for extracranial tortuous VAs include conservative management or some form of surgical microvascular decompression (MVD). The authors report on a patient with a congenital anomalous VA loop causing cervical nerve root compression. Successful MVD was conducted with relief of the patient's symptoms. A novel sling technique was used for mobilization of the VA. To the authors' knowledge, this is the first MVD described utilizing this technique.

There is evidence that primary hemifacial spasm (HFS) in the majority of patients is related to a vascular compression of the facial nerve at its root exit zone (REZ). As a consequence, the hyperexcitability of facial nerve generates spasms of the facial muscles. Microvascular decompression (MVD) of the facial nerve near its REZ has been established as an effective treatment of HFS. Intra-operative disappearance of abnormal muscle responses (lateral spread) elicited by stimulating one of the facial nerve branches has been used as a method to predict MVD effectiveness. Other neurophysiologic techniques, such as facial F-wave, blink reflex and facial corticobulbar motor evoked potentials (FCoMEP), are feasible to intra-operatively study changes in excitability of the facial nerve and its nucleus during MVDs. Intra-operative neuromonitoring with the mentioned techniques allows a better understanding of HFS pathophysiology and helps to optimise the MVD.

OBJECTIVE:Conventional surgical treatment of bilateral ophthalmic aneurysms would require bilateral craniotomies and bilateral neck dissections for proximal control of the cervical internal carotid artery (ICA). We present a semiemergent case where bilateral ophthalmic artery aneurysms were clipped using a unilateral mini-pterional craniotomy and contralateral proximal cervical ICA control while employing the Sugita head frame. CLINICAL PRESENTATION/METHODS:A 37-year-old female presented with progressive right retro-orbital headaches. MRI/A revealed a right carotid-ophthalmic aneurysm as well as a small aneurysm on the left carotid-ophthalmic segment. Given the young age and medial orientation of the right aneurysm, direct surgical clipping was planned. It was our thought that a contralateral approach would afford us the best chance to clip the right medially pointing aneurysm fully without optic nerve retraction while having proximal control via exposure of contralateral cervical ICA. METHODS:After gaining proximal ICA control from right neck dissection, the Sugita frame was rotated to allow for a left pterional craniotomy. The right medially pointing ophthalmic aneurysm was clipped without optic nerve retraction. After dissection of the distal dural ring and gaining proximal control, the left aneurysm was clipped. Postoperatively, the patient remained intact without any visual complaints, and both aneurysms were obliterated on angiography. CONCLUSION/CONCLUSIONS:Our case illustrates safety and control while clipping bilateral ophthalmic artery aneurysms via a unilateral mini-pterional approach and utility of the Sugita head frame.

BACKGROUND: An intracranial posterior circulation revascularization procedure in the form of a side-to-side in situ posterior inferior cerebellar artery (PICA)-PICA bypass operation was introduced in 1991. This elegant and apparently low-risk operation is performed infrequently. Thus, the operative nuances used in this procedure have not been well reported, limiting the scope of treatment modalities of vertebral artery-PICA aneurysms and vertebral dissections. OBJECTIVE: To repair an incidental right-sided PICA aneurysm noted in a 51-year-old woman in magnetic resonance imaging and subsequent angiography. METHODS: The patient underwent side-to-side in situ PICA-PICA bypass surgery. RESULTS: Immediate indocyanine green angiography suggested that the PICA distal to the aneurysms was filling in a retrograde fashion through the bypass. On the following day, the patient was taken for coil embolization of the aneurysm. However, angiography images revealed that the aneurysm was spontaneously thrombosed, the proximal PICA was patent, and the PICA distal to the aneurysms was filling in a retrograde fashion, as suspected in intraoperative indocyanine green angiography. No further treatments were done. The patient recovered fully. CONCLUSION: We describe in detail the preoperative evaluation, decision process, and operative techniques for a side-to-side in situ PICA-PICA bypass operation, which is a relatively safe and elegant posterior circulation bypass procedure

OBJECT: Chordomas are rare malignant neoplasms arising predominantly at the sacrum and skull base. They are uniformly lethal unless treated with aggressive resection and proton beam irradiation. The authors present results of the surgical management of a large number of patients with clivus chordomas. Factors that influence the surgeon's ability to achieve radical tumor resection are also evaluated. METHODS: Between 1991 and 2005, 71 patients with clivus chordomas underwent surgery. The average follow-up was 66 months (median 60 months, range 3-189 months). Sixty-five patients had complete records that were analyzed in the present report. Thirty-five percent of them had undergone surgery before being treated by the authors. They were evaluated with MR imaging and CT scanning and underwent surgery utilizing a variety of skull base techniques aimed at achieving radical excision. Many also underwent postoperative radiation, usually in the form of proton beam therapy. The patients were followed up with serial imaging at regular intervals as well as with neurological evaluation. RESULTS: Radical tumor resection was achieved in 58% of the group. The overall 5-year survival rate was 75%. Radical resection had a positive impact on survival. The ability to achieve radical resection was dependent on the preoperative tumor volume and the number of anatomical areas involved by the tumor. Cranial nerve impairment and CSF leakage were the most frequent postoperative complications. CONCLUSIONS: Radical excision is the ideal surgical goal in the treatment of clival chordomas and can be achieved with reasonable risks. Several different surgical approaches may be necessary to accomplish this

The management of adult patients with Chiari malformation associated with syrinx remains controversial. Although an abundance of literature exists for the pediatric population, there is an absence of guidelines for the adult population. It is unclear which of the different surgical approaches is appropriate in patients with Chiari I malformations and syringomyelia. A 36-year-old female patient had a posterior fossa decompression 3years prior to recurrence. The patient developed recurrent symptoms with sensory loss and hyperesthesia in the right upper extremity. MRI revealed decreased cerebrospinal fluid flow at the craniocervical junction. The patient was taken to the operating room for revision of the posterior fossa decompression, lysis of adhesions and duraplasty. Re-exploration of a Chiari decompression, lysis of adhesions and revision duraplasty is an effective treatment option for recurrent syringomyelia

OBJECT: Intramedullary spinal cord tumors can displace the surrounding neural tissue, causing enlargement and distortion of the normal cord anatomy. Resection requires a midline myelotomy to avoid injury to the posterior columns. Locating the midline for myelotomy is often difficult because of the distorted anatomy. Standard anatomical landmarks may be misleading in patients with intramedullary spinal cord tumors due to cord rotation, edema, neovascularization, or local scar formation. Misplacement of the myelotomy places the posterior columns at risk of significant postoperative disability. The authors describe a technique for mapping the dorsal column to accurately locate the midline. METHODS: A group of 10 patients with cervical and thoracic intramedullary spinal cord lesions underwent dorsal column mapping in which a strip electrode was used to define the midline. After the laminectomy and durotomy, a custom-designed multielectrode grid was placed on the exposed dorsal surface of the spinal cord. The electrode is made up of 8 parallel Teflon-coated stainless-steel wires (76-microm diameter, spaced 1 mm apart) embedded in silastic with each of the wires stripped of its insulating coating along a length of 2 mm. This strip electrode maps the amplitude gradient of conducted spinal somatosensory evoked potentials elicited by bilateral tibial nerve stimulation. Using these recordings, the dorsal columns are topographically mapped as lying between two adjacent numbers. RESULTS: The authors conducted a retrospective analysis of the preoperative, immediate, and short-term postoperative neurological status, focusing especially on posterior column function. There were 8 women and 2 men whose mean age was 52 years. There were 4 ependymomas, 1 subependymoma, 1 gangliocytoma, 1 anaplastic astrocytoma, 1 cavernous malformation, and 2 symptomatic syringes requiring shunting. In all patients the authors attempted to identify the midline by using anatomical landmarks, and then proceeded with dorsal column mapping to identify the midline electrophysiologically. In the 2 patients with syringomyelia and in 5 of the patients with tumors, the authors were unable to identify the midline anatomically with any certainty. In 2 patients with intramedullary tumors, they were able to identify the midline anatomically with certainty. Dorsal column mapping allowed identification of the midline and to confirm the authors' anatomical localization. In 2 patients with intramedullary tumors, posterior column function was preserved only on 1 side. All other patients had intact posterior column function preoperatively. CONCLUSIONS: Dorsal column mapping is a useful technique for guiding the surgeon in locating the midline for myelotomy in intramedullary spinal cord surgery. In conjunction with somatosensory evoked potential, motor evoked potential, and D-wave recordings, we have been able to reduce the surgical morbidity related to dorsal column dysfunction in this small group of patients