Daniel L. Keene

Purpose Cerebellar mutism is a common complication of posterior fossa tumor resection. We observed marked, preoperative brainstem compression on MR imaging, among patients who developed postoperative mutism. This study was designed to investigate if an association was indeed present. Materials and methods Patients (18 months–18 years) undergoing resection of a midline, posterior fossa tumor were retrospectively reviewed. Demographic data, tumor pathology, mutism onset and duration, and postoperative complications were obtained from hospital records. Pre- and postoperative MR images were studied to assess tumor size and the severity of pons compression (an estimate of the mechanical and distortional forces imparted by the tumor). Results Patients with mutism showed greater preoperative pons compression and a greater increase in postoperative pons diameter. Conclusion We predict that brainstem compression may represent white-matter injury from (1) surgical manipulation and traction, and (2) axonal damage caused by the release of the tumor’s compressive force and ensuing axon distortion and dysfunction. The results provide support that mutism may be largely caused by white-matter damage disrupted axon integrity and function.

To determine the incidence and characteristics of pediatric patients with central nervous system (CNS) germ cell tumors (GCT) in Canada.

Objectives Cerebral vascular disease has been reported as a long-term complication of cranial radiotherapy. The purpose of this study was to examine the frequency and risk factors associated with development of cerebral vascular disease in children after cranial radiation. Materials and methods A retrospective chart review of all cancer patients treated between 1985 and 2003 who were under the age of 18 years at the time of initial radiotherapy was performed. Variables examined include diagnosis and site of malignancy, age at the time of radiotherapy, sex, total radiation dosage, number of fractions, duration, and whether the patient had proven cerebral vascular event. Results Two hundred and forty-four patients met the study criteria. One hundred and 13 cases involved tumors of the central nervous system. The remaining patients had systemic neoplastic disease. Post radiation cerebral vascular disease occurred in 11 (5%) patients, and all but one patient had a tumor involving the central nervous system (mainly in the posterior fossa and supratentorial midline). Conclusion There is an increased risk of cerebral vascular disease after radiation therapy in childhood, especially in children who received high dose radiation at the posterior fossa and supratentorial axial region.

Electrocorticography (ECOG), the intra-operative recording of cortical potentials, has played an important role in the surgical management of patients with medically refractory epilepsy. It has been used 1) to localize the epileptogenic tissue; 2) map out cortical functions; and 3) predict the success of the surgery. Despite its common use, few studies have been done to prove its effectiveness in these areas. The technique used in children for recording ECOG is very similar to that used in adults except for the limitations imposed by the child's age. Anaesthesia must often be used. Based upon a computerized medical literature search, a review of this procedure was done. Pre-resection localization, and post-resection prediction of outcome was done for temporal and extra-temporal resection, both lesional and nonlesional. Most of the available studies were in adult patients. All were retrospective in nature. Evidence for the role of pre-resection ECOG in determining the degree of resection felt necessary to obtain good clinical outcome was limited. Similarly the post-resection ECOG predication of surgical outcome was restricted.

Alfentanil is a potent, short-acting opioid agent which has been used during balanced anaesthesia in children undergoing the surgical excision of epileptic foci. After the observation that this agent had the potential to induce epileptic seizures, we questioned the frequency of this occurrence in this group of patients. Twelve patients (6 males, 6 females) undergoing surgical excision of an epileptic foci were prospectively followed. For each patient an electrocorticogram was recorded for 30 minutes before and after receiving alfentanil 20 micrograms/kg intravenously. The frequency of epileptiform abnormalities before and after drug administration was evaluated. When the electrocorticogram no longer showed the effects of alfentanil administration, methohexital 0.5 microgram/kg was given intravenously. Alfentanil induced significant activation of epileptiform discharges among 83% of these patients. Twenty-five per cent had an electrographic seizure. In comparison, methohexital induced significant activation of epileptiform discharges in 50% of these patients. None experienced electrographic seizures. As alfentanil can induce electrographic seizures in patients known to have epilepsy, caution is advised in its use in this group of patients.