Fred Gentili

Expanded endoscopic endonasal approach for anterior cranial base and suprasellar lesions: indications and limitations.

OBJECTIVEThe traditional boundaries of the transsphenoidal approach can be expanded to include the region from the cribriform plate of the anterior cranial fossa to the foramen magnum in the anteroposterior plane. The introduction of endoscopy to transsphenoidal surgery, with its improved illumination and wider field of view, has added significant further potential for the resection of a variety of cranial base lesions. We review our experience with the expanded endoscopic endonasal approach in a series of 22 patients with anterior cranial base and supradiaphragmatic lesions. METHODSFrom June 2005 to June 2007, the expanded endoscopic endonasal approach was used in 22 patients with the following pathologies: 6 craniopharyngiomas; 4 esthesioneuroblastomas; 3 giant pituitary macroadenomas; 2 suprasellar Rathkes pouch cysts; 2 angiofibromas; and 1 each of suprasellar meningioma, germinoma, ethmoidal carcinoma, adenoid cystic carcinoma, and large suprasellar arachnoid cyst. This study specifically focused on the surgical indications and approaches to these lesions and the surgical results, complications, and limitations associated with this technique. RESULTSGross total tumor removal, as assessed by postoperative magnetic resonance imaging, was possible in the majority of patients (73%), with the exception of the craniopharyngioma group, in which only 1 lesion was completely removed. There were no permanent neurological complications except for increased visual disturbance in 1 patient. Other complications included cerebrospinal fluid fistulae in 4 patients (18%) and meningitis in 1 patient (5%). There was no operative mortality. Large lesions, significant lateral extension, encasement of neurovascular structures, and brain invasion in malignant lesions are considered some of the contraindications for this technique. CONCLUSIONThe expanded endoscopic endonasal approach is a promising minimally invasive alternative to open transcranial approaches for selective lesions of the midline anterior cranial base. The avoidance of craniotomy and brain retraction and reduced neurovascular manipulation with less morbidity are potential advantages. Major complications have been few, but there are also limitations with this technique. This approach should be included in the armamentarium of cranial base surgeons and considered as an option in the management of selected patients with these complex pathologies.

Expanded endoscopic endonasal approach for treatment of clival chordomas: early results in 12 patients.

OBJECTIVEWe report our recent experience with an expanded purely endoscopic endonasal approach for the treatment of clival chordomas. METHODSTwelve patients underwent an expanded endoscopic approach for excision of cranial base chordomas at Toronto Western Hospital. Two patients had undergone a previous craniotomy for excision of a significant lateral intracranial extension of the tumor. All other patients had mainly centrally located lesions. Three patients had recurrent tumors. This study focused on the surgical approach, results, and complications associated with this approach. RESULTSDiplopia caused by VIth nerve palsy was the most common presenting symptom and was observed in seven patients. Gross total resection of the tumor was achieved in seven patients (58%). Four patients had complete recovery of their preoperative diplopia. One patient (8%) presented with new hemiparesis postoperatively. Four patients (33%) had a cerebrospinal fluid leak postoperatively; two were treated by lumbar drainage, and two required a secondary surgical repair. All newly diagnosed patients underwent adjuvant radiotherapy. There was no mortality. The short-term outcome was excellent in all but one patient. No recurrence was observed at the median follow-up period of 16 months. CONCLUSIONThe expanded endoscopic endonasal approach is a valid minimally invasive alternative for the treatment of centrally located clival chordomas or as an adjunct for the central part of chordomas with lateral extension. The early results of this technique indicate at least equivalency to more extensive open approaches, and its versatility may widen the horizon of surgical management of these aggressive lesions. The challenge with the cerebrospinal fluid leakage is being addressed with novel local flap repair techniques. This approach should be in the armamentarium of cranial base surgeons as an option in the management of clival chordomas.

Nerve injection injury with local anesthetic agents: a light and electron microscopic, fluorescent microscopic, and horseradish peroxidase study.

Although regional anesthesia is generally considered to have no neurotoxic properties, significant nerve injury has been reported after its use. The present study was undertaken to examine possible toxic effects on peripheral nerve tissue of local anesthetic agents. We injected the sciatic nerve of

Esthesioneuroblastoma: The Princess Margaret Hospital experience

Esthesioneuroblastoma is rare. The aim of the study was to review our experience and to evaluate the staging system and treatment that best correlates with the patient outcome.

Preoperative Radiotherapy for Adult Head and Neck Soft Tissue Sarcoma: Assessment of Wound Complication Rates and Cancer Outcome in a Prospective Series

Combination surgery and radiotherapy (RT) is frequently used in soft tissue sarcoma (STS). Because lower doses and smaller irradiation volumes are possible in preoperative RT (pre-op RT), this approach can be especially valuable in anatomic settings where critical organs are in close proximity to the RT target area. A recent multicenter phase III trial (SR.2 trial of the National Cancer Institute of Canada Clinical Trials Group) comparing pre-op RT against post-op RT for extremity STS has shown significantly higher major wound complication rates (35%) with pre-op RT. We postulated that wound complication rates may be less frequent in the head and neck with better vascularity and wider use of secondary wound reconstruction. Using a prospective database, we identified 40 consecutive patients with head and neck STS treated with pre-op RT (50 Gy) and subsequent (4 to 6 weeks later) resection between 1/89 and 8/99 in a single institution setting. Major wound complications (MWC) were classified by the identical criteria used in the SR.2 trial. Intracranial extension was evident in 5 patients, whereas 50% of the patients had large tumors (> 5 cm). Deep tumor was present in 34 (85%), and 6 (15%) were superficial to fascia. In this series, 31 patients (77.5%) had secondary reconstruction of the acquired soft tissue deficit. The actuarial 2-year local relapse-free rate was 80%, and the metastatic relapse-free rate was 85%. Major wound complications occurred in 8 of 40 patients (20%) within 120 days of surgery according to the SR.2 criteria: secondary wound surgery (3), readmission or prolonged hospital admission for wound care (2), deep packing (0), prolonged dressing changes (2), and invasive procedure for wound care (1). The latter was a minor wound management problem (a single outpatient drainage of a seroma) for the combined rate of 8/20 or 20%. Our findings show that (1) pre-op RT in head and neck STS is associated with lower rates of major wound complications compared to extremity cases; (2) pre-op RT provides high rates of local control in an adverse group of cases of adult head and neck STS; (3) the choice of scheduling of RT should be based on anatomic issues with emphasis on the trade-offs between RT doses and volumes versus wound morbidity for individual patients. This is especially important when tumor may be adjacent to critical head and neck structures which may be protected from the high-dose RT area.

Clinical and experimental aspects of injection injuries of peripheral nerves.

Injury to peripheral nerves complicating deep intramuscular injections of antibiotic and other agents is well recognized and can result in significant permanent neurological deficit. The purpose of this paper is to review the subject of nerve injection injuries, and report on a series of recent experimental studies carried out in this laboratory designed to improve our understanding of the pathophysiology of this condition and help provide a rational basis for its treatment. A wide variety of chemotherapeutic, prophylactic, and local anaesthetic agents in common use were injected into the sciatic nerve of the adult Wistar rat. Both intrafascicular and extrafascicular injections were examined. Results revealed that the site of injection was the most crucial factor in determining the degree of nerve fiber injury. Following intrafascicular injection, the degree of injury varied significantly, depending upon the specific agent injected. The most severe injuries were associated with wide-spread axonal and myelin degeneration. Pathological alterations in the nerve were evident as early as 30 minutes following injection injury. Regeneration was a constant finding in nerve damage by injection of the various agents. The mechanism of injury appeared to be a direct toxic effect of the injected compound on neural tissue, with an associated break down of the blood-nerve barrier.

Amyloid destructive spondyloarthropathy causing cord compression: related to chronic renal failure and dialysis.

Destructive spondyloarthropathy is a recently recognized disease that has not been reported in the neurosurgical literature. It is associated with spinal amyloid deposition in long-term renal failure and dialysis, and it occurs increasingly as the number of dialysis patients and their survival times increase. Clinically, there is a multisegmental and often rapidly progressive radiculomyelopathy that may require emergency stabilization. The radiological features are disc space narrowing with erosion of vertebral end plates and subarticular cysts. The pathological features include deposition of amyloid, which stains with Congo Red and antibodies to beta-2-microglobulin. We present two cases with clinical, radiological, and pathological features and a review of the literature.

Image-guided, intensity-modulated radiation therapy (IG-IMRT) for skull base chordoma and chondrosarcoma: preliminary outcomes

BACKGROUND We report our preliminary outcomes following high-dose image-guided intensity modulated radiotherapy (IG-IMRT) for skull base chordoma and chondrosarcoma. METHODS Forty-two consecutive IG-IMRT patients, with either skull base chordoma (n = 24) or chondrosarcoma (n = 18) treated between August 2001 and December 2012 were reviewed. The median follow-up was 36 months (range, 3-90 mo) in the chordoma cohort, and 67 months (range, 15-125) in the chondrosarcoma cohort. Initial surgery included biopsy (7% of patients), subtotal resection (57% of patients), and gross total resection (36% of patients). The median IG-IMRT total doses in the chondrosarcoma and chordoma cohorts were 70 Gy and 76 Gy, respectively, delivered with 2 Gy/fraction. RESULTS For the chordoma and chondrosarcoma cohorts, the 5-year overall survival and local control rates were 85.6% and 65.3%, and 87.8% and 88.1%, respectively. In total, 10 patients progressed locally: 8 were chordoma patients and 2 chondrosarcoma patients. Both chondrosarcoma failures were in higher-grade tumors (grades 2 and 3). None of the 8 patients with grade 1 chondrosarcoma failed, with a median follow-up of 77 months (range, 34-125). There were 8 radiation-induced late effects-the most significant was a radiation-induced secondary malignancy occurring 6.7 years following IG-IMRT. Gross total resection and age were predictors of local control in the chordoma and chondrosarcoma patients, respectively. CONCLUSIONS We report favorable survival, local control and adverse event rates following high dose IG-IMRT. Further follow-up is needed to confirm long-term efficacy.

Sinonasal Carcinomas: Epidemiology, Pathology, and Management

Sinonasal carcinomas are uncommon neoplasms accounting for approximately 3% to 5% of all upper respiratory tract malignancies. Sinonasal malignancies in most cases do not cause early symptoms and present in an advanced stage of disease. Exact staging necessitates a clinical and endoscopic examination with biopsy and imaging. Tumor resection using an open or endoscopic approach is usually considered the first treatment option. In general, sinonasal carcinomas are radiosensitive, so adjuvant or neoadjuvant radiation treatment may be indicated in advanced disease. Multidisciplinary surgical and medical oncologic approaches, including ablation and reconstruction, have enhanced the survival outcome over the past few decades.

Monitoring of Sensory Evoked Potentials During Surgery of Skull Base Tumours

Despite advances in instrumentation and the use of microsurgical techniques, neurosurgical procedures involving extensive areas of skull base or other critical areas of brain still carry significant risk for neurological injury. The use of intraoperative recording of sensory evoked potentials (SEP) has been advocated to monitor neurologic function during these major neurosurgical procedures to reduce the risk of injury to neural structures. This report summarizes our experience with intraoperative monitoring of SEP in over 200 patients, and details our findings in a group of 12 patients with skull base and posterior fossa tumours. Somatosensory evoked potentials (SSEP) were monitored in all patients, and brain stem auditory evoked potentials (BAEP) in five. While minor changes in BAEP and SSEP parameters were noted in most patients, significant changes occurred in five. Irreversible loss of BAEP in one patient was associated with complete hearing loss postoperatively. Marked, persistent alteration of both BAEP and SSEP was associated with postoperative brainstem dysfunction. No patient with stable BAEP and SSEP at the end of the procedure suffered additional neurological deficit. We conclude that intraoperative SEP monitoring may be valuable in minimizing neural injury during major neurosurgical procedures.