Faculty Bibliography

The authors present 2 cases of far-lateral lumbar disc herniations treated surgically via an extreme-lateral transpsoas approach. The procedure was performed using the MaXcess minimally invasive retractor system to access and successfully remove the disc fragments without complication. To the authors' knowledge, these are the first reported cases of using a minimally invasive retroperitoneal approach for the treatment of far-lateral disc herniations.

OBJECTIVES/HYPOTHESIS: Surgical resection of intradural pathology through an endonasal corridor creates defects that communicate the subarachnoid space with the sinonasal tract. Reconstruction of these defects with vascularized tissue is superior to any other method. The purpose of this study is to describe a novel vascularized pedicled flap from the middle turbinate (MT) mucosa and to assess its feasibility using a cadaveric model. METHODS: Twelve middle turbinate flaps (MTFs) were raised in six fresh cadaveric heads previously injected with colored silicone. Arteries supplying the MT were identified as the turbinate mucoperiosteum was harvested from both its medial and lateral aspects. Length and surface area of the flaps, as well as their ability to cover dural defects of the sella, planum sphenoidale, and fovea ethmoidalis reach were noted. RESULTS: All MTFs adequately covered defects of the planum and fovea ethmoidalis; however, two of the twelve MTFs were not suitable to cover a sellar defect. The mean surface area of the MTFs was 5.6 cm(2). As an independent factor surface area did not correlate with the ability of the flap to cover the sellar defects. However, those flaps that were not suitable for sellar repair were less than 4.0 cm in length. CONCLUSIONS: Harvesting of a vascular pedicle flap from the MT is feasible, albeit technically demanding. It should be considered as an alternative for the reconstruction of small defects of the fovea ethmoidalis, planum, and sella, particularly for patients for whom a reconstruction with vascularized tissue is desirable but the nasoseptal flap is not available.

OBJECTIVES/HYPOTHESIS: We sought to investigate the anatomical relation of the intrasphenoid septations to the internal carotid artery (ICA). METHODS: Twenty-seven preoperative high-resolution computed tomography angiographic (CTA) scans with 1 mm of separation acquisition were examined. In addition, an endoscopic endonasal approach and high-resolution computed tomography were done on 27 fresh-frozen cadaveric heads. The number of intrasphenoid septa and their relation to the ICAs were analyzed endoscopically and radiologically. Complete and incomplete septations were included in the analysis. A total of 54 sphenoid sinuses were studied. RESULTS: Out of 27 sphenoid sinuses radiologically studied from real patients, 23 (85%) and 11 (41%) had at least one or two septa, respectively, touching one of the ICA. Out of 27 sphenoid sinuses endoscopically examined from cadavers (excluding one conchal type), 24 (89%) had at least one septation inserted in the ICAs. Two or more septations were inserted in the carotid prominence in 48% of sphenoid sinuses. The radiological examination of the anatomical specimens revealed similar results, with discrepancy in just one case (1/27) where it did not identify an incomplete septation inserting at ICA. No significant differences were found between the groups. From a total of 54 sphenoid sinuses studied, 47 (87%) had at least one septum related to the ICA, and only 13% presented a typical isolated midline septation. CONCLUSIONS: As demonstrated both radiographically and endoscopically, most intrasphenoidal septa insert at the parasellar or paraclival carotid prominence. As such, extreme care should be taken when identifying and removing these septations intraoperatively.

OBJECT: Meningiomas of the cerebral convexity are often surgically curable because both the mass and involved dura mater can be removed. Stereotactic radiosurgery has become an important primary or adjuvant treatment for patients with intracranial meningiomas. The authors evaluated clinical and imaging outcomes in patients with convexity meningiomas after radiosurgery. METHODS: The patient cohort consisted of 125 patients with convexity meningiomas managed using radiosurgery at some point during an 18-year period. The patient series included 76 women, 55 patients who had undergone prior resection, and 6 patients with neurofibromatosis Type 2. Tumors were located in frontal (80 patients), parietal (24 patients), temporal (12 patients), and occipital (9 patients) areas. The WHO tumor grades in patients with prior resections were Grade I in 34 patients, Grade II in 15 patients, and Grade III in 6 patients. Seventy patients underwent primary radiosurgery and therefore had no prior histological tumor diagnosis. The mean tumor volume was 7.6 ml. Radiosurgery was performed using the Leksell Gamma Knife with a mean tumor margin dose of 14.2 Gy. RESULTS: Serial imaging was evaluated in 115 patients (92%). After primary radiosurgery, the tumor control rate was 92%. After adjuvant radiosurgery, the control rate was 97% for Grade I tumors. The actuarial tumor control rates at 3 and 5 years for the entire series were 86.1+/-3.8% and 71.6+/-8.6%, respectively. For patients with benign tumors (Grade I) and those without prior surgery, the actuarial tumor control rate was 95.3+/-2.3% and 85.8+/-9.3%, respectively. Delayed resection after radiosurgery was performed in 9 patients (7%) at an average of 35 months. No patient developed a subsequent radiation-induced tumor. The overall morbidity rate was 9.6%. Symptomatic peritumoral imaging changes compatible with edema or adverse radiation effects developed in 5%, at a mean of 8 months. CONCLUSIONS: Stereotactic radiosurgery provides satisfactory control rates either after resection or as an alternate to resection, particularly for histologically benign meningiomas. Its role is most valuable for patients whose tumors affect critical neurological regions and who are poor candidates for resection. Both temporary and permanent morbidity are related to brain location and tumor volume.

OBJECTIVE: Patients who have a schwannoma of the facial nerve (facial schwannoma, facial neuroma) can be managed with observation, surgical resection, stereotactic radiosurgery, or fractionated radiotherapy. Attempted complete resection is associated with facial weakness. The role of radiosurgery in these patients remains to be defined. METHODS: We reviewed the clinical and imaging outcomes in patients who underwent gamma knife radiosurgery for a facial schwannoma. RESULTS: Six patients had radiosurgery and were followed for a mean and median of 46.6 and 61.5 months, respectively (21-85 months). Three had a previous resection, and in 3 the diagnosis was made based on clinical and imaging criteria. All patients had facial nerve symptoms (5 had weakness and 1 had muscle twitching). House-Brackmann grades before radiosurgery were as follows: 1 (n = 1), 2 (n = 3), 3 (n = 1), and 6 (n = 1). The radiosurgery margin dose was 12 or 12.5 Gy. On later imaging, 3 tumors had regressed (with the longest follow-up duration) and 3 were unchanged. All patients had preservation of their preradiosurgery facial function. No other adverse effects were noted and all patients maintained their preradiosurgery level of hearing. CONCLUSION: Over a mean of almost 4 years of follow-up, radiosurgery was shown to be a safe and effective management for residual and newly diagnosed facial schwannomas.

OBJECTIVE: Radiation-induced meningiomas of the brain are typically managed with surgical resection. Stereotactic radiosurgery (SRS) has become an important primary or adjuvant management for patients with intracranial meningiomas, but the value of this approach for radiation-induced tumors is unclear. METHODS: This series consisted of 19 patients (mean age, 40 years) with 24 tumors. The patients met criteria for a radiation-induced meningioma and underwent gamma knife radiosurgery. Seven patients had undergone a previous resection. The World Health Organization tumor grades for those with prior histology were Grade I (n = 5) and Grade II (n = 2). The median tumor volume was 4.4 cm3. Radiosurgery was performed using a median margin dose of 13 Gy. RESULTS: Serial imaging was evaluated in all patients at a median follow-up of 44 months. The control rate was 75% after primary radiosurgery. Delayed resection after radiosurgery was performed in 5 patients (26%) at an average of 39 months. The median latency between radiation therapy for original disease and SRS for radiation-induced meningiomas was 29.7 years (range, 7.3-59.0 years). The overall survival after SRS was 94.1% and 80.7% at 3 and 5 years, respectively. No patient developed a subsequent radiation-induced tumor. The overall morbidity rate was 5.3% (1 optic neuropathy). Asymptomatic peritumoral imaging changes compatible with an adverse radiation effect developed in 1 patient. CONCLUSION: SRS provides satisfactory control rates either after resection or as an alternative to resection. Its role is most valuable for patients whose tumors affect critical neurological regions and who are poor candidates for resection.

OBJECTIVE: Stereotactic radiosurgery has become an important primary or adjuvant minimally invasive management strategy for patients with intracranial meningiomas with the goals of long-term tumor growth prevention and maintenance of patient neurological function. We evaluated clinical and imaging outcomes of meningiomas stratified by histological tumor grade. METHODS: The patient cohort consisted of 972 patients with 1045 intracranial meningiomas managed during an 18-year period. The series included 70% women, 49% of whom had undergone a previous resection and 5% of whom had received previous fractionated radiation therapy. Tumor locations included middle fossa (n = 351), posterior fossa (n = 307), convexity (n = 126), anterior fossa (n = 88), parasagittal region (n = 113), or other (n = 115). RESULTS: The overall control rate for patients with benign meningiomas (World Health Organization Grade I) was 93%. In those without previous histological confirmation (n = 482), tumor control was 97%. However, for patients with World Health Organization Grade II and III tumors, tumor control was 50 and 17%, respectively. Delayed resection after radiosurgery was necessary in 51 patients (5%) at a mean of 35 months. After 10 years, Grade 1 tumors were controlled in 91% (n = 53); in those without histology, 95% (n = 22) were controlled. None of the patients developed a radiation-induced tumor. The overall morbidity rate was 7.7%. Symptomatic peritumoral imaging changes developed in 4% of the patients at a mean of 8 months. CONCLUSION: Stereotactic radiosurgery provided high rates of tumor growth control or regression in patients with benign meningiomas with low risk. This study confirms the role of radiosurgery as an effective management choice for patients with small to medium-sized symptomatic, newly diagnosed or recurrent meningiomas of the brain.