Brainstem compression: a predictor of postoperative cerebellar mutism.

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.

Posterior fossa dimension and volume estimates in pediatric patients with Chiari I malformations.

INTRODUCTION: Chiari I malformations (CMI) involve pathological hindbrain abnormalities reported to be correlated with a hypoplastic posterior fossa. CMI was traditionally characterized by the downward herniation of the cerebellar tonsils with a descent of 5 mm or more below the foramen magnum. The fullness of the cisterna magna and CSF flow at the level of the cervicomedullary junction have been shown to be more useful in selecting symptomatic patients for surgical decompression. The present study calculates posterior fossa dimension and volume estimates in pediatric patients using magnetic resonance imaging. The combination of neuroradiological and clinical findings is used to re-examine the criteria used for diagnosis and treatment of pediatric CMI patients. MATERIALS AND METHODS: A retrospective chart review was conducted on patients who were admitted to the Division of Neurosurgery of the Children's hospital of Eastern Ontario between 1990 and 2007. Clinical and radiological assessments were performed on all patients. Posterior fossa volumes (PFV) and intracranial volumes (ICV) were measured from sagittal head magnetic resonance imaging scans using the Cavalieri method. RESULTS: Sixty-one CMI patients were identified. There were 32 male and 29 female patients with a mean age of 10 years (range: 8 weeks-18 years). Thirty-four (55%) of these patients were symptomatic with scoliosis (38%), suboccipital headaches (29%), and motor/sensory deficits (26%) being the most prominent symptoms. The mean PFV/ICV ratio for all the CMI patients (0.110) was found to be statistically smaller than that of the control patients (0.127, p=0.022). Mean PFV/ICV ratios for asymptomatic and symptomatic CMI patients were found to be similar for children aged 0-9 years (p=0.783) but different for children aged 10-18 years (p=0.018). DISCUSSION: Mean PFV values were found to be smaller in pediatric CMI patients than control patients; this complements earlier studies in adults and supports the present theory concerning the pathophysiological mechanism of CMI. Subtle morphometric differences among asymptomatic and symptomatic patients aged 0-9 years stress the importance of monitoring asymptomatic patients for the onset of symptoms in their adult years. Symptom development in CMI is likely multifactorial and is much more extensive than the degree of cerebellar tonsillar herniation.

Radioisotope shuntograms at the Children's Hospital of Eastern Ontario.

INTRODUCTION: Nuclear medicine shuntograms using the radiotracer technetium-99m diethylenetriaminepentaacetic acid have been used for many years as an additional method to assess shunt patency and performance. METHODS: The medical records of all children who had shuntograms performed at the Children's Hospital of Eastern Ontario between January 13, 2000, and January 10, 2003, were retrospectively reviewed. There was a total of 68 procedures in 56 patients with an average age of 9 years 3 months. During the same period there were 123 shunt revisions. RESULTS: Forty-two shuntograms were reported as normal. Of these, ten were identified to be false negative. Two children with fractured shunts had shuntograms performed in order to assess for cerebrospinal fluid flow patency; the shuntograms were identified to be normal, confirming shunt dependence, and the shunt replaced. Twenty-six shuntograms were reported as abnormal in 24 patients; 17 went on to have surgery and the shunt malfunction was confirmed. Seven patients did not require surgery: five were declared shunt independent, two patients clinically improved after severe constipation was treated. CONCLUSIONS: Approximately one fourth of all shuntograms reported as normal are not (false-negative rate=25%). Review of five other major studies between 1980 and 2003 have reported false-negative rates between 2 and 36%, which may be explained by variations in shuntogram protocols. A standardized method is proposed.

Medulloblastoma in children--the Ottawa experience.

A retrospective review of 36 children diagnosed with medulloblastoma in the Ottawa area between 1974 and 1997 was completed (mean age 7.8+/-4.2 years, range 1.2-15.3 years). Via a suboccipital approach, complete tumor resection was achieved in 75% and subtotal resection (>90%) in 25%, without any operative mortality. The tumor was located in the vermis in 39% and in the cerebellar hemisphere in 11%; it occupied both locations in 50%. In 47% of the children a ventriculoperitoneal shunt was required. Postoperatively, craniospinal radiation at 3600 cGy with a boost to the posterior fossa was administered. Chemotherapy was used in 56%. The 1-year survival rate was 92%, and survival plateaued at 54% at 5 years. Children less than 3 years of age fared worse than those over 3 years old. While the male-to-female ratio was 1.6:1, there was no gender difference in survival. Chang's classification was used to grade the tumors. T stage did not have an impact on survival, but M stage did. No statistically significant difference in survival was found between the patients who had a total resection and those who had a subtotal resection. There was no difference in survival in terms of tumor location, hydrocephalus or ventriculoperitoneal shunt. Chemotherapy showed no survival benefit. The recurrence rate was 26%, and its timing followed Collin's law. Recurrence led to death within 1-9 months. GH deficiency was diagnosed in 5 patients and hypothyroidism in 4 patients. The mean follow-up time was 4.4+/-3.7 years, with a range of 2.5 months to 16.5 years. Fourteen patients died, 5 were lost to follow-up, and 7 were transferred to adult care without persistent disease. Ten children are presently being followed up by the Neuro-oncology Clinic. Four children continue to be followed through psychology services. Our results are comparable to those in larger series, and are similar to those of the Montreal Children's Hospital.

Electrocorticography.

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.

Temporal lobe focal cortical dysplasia: MRI imaging using FLAIR shows lesions consistent with neoplasia.

Focal cortical dysplasia (FCD), a form of neuronal migration disorder, is a malformative lesion of the neocortex that occurs during development of the brain. It can cause partial and generalized epilepsy. Seizures occur at an early age and are often resistant to medication. Surgical resection has been found to be beneficial in these patients. Dual pathology, in the form of mesial temporal sclerosis, has been associated with FCD. At the Children's Hospital of Eastern Ontario, four patients with temporal lobe FCD have recently, been identified. This paper discusses how these children presented and how they were managed, with particular emphasis on their MRI findings and differential diagnoses. In three of the four patients neuroimaging studies showed lesions consistent with a neoplastic process because of the large volume and mass effect. Radiologically, FCD may mimic the MRI appearance of tumors, such as dysembryoplastic neuroepithelial tumors, primitive neuroectodermal tumors, gangliogliomas, oligodendrogliomas, and astrocytomas. These lesions are best visualized on fluid-attenuated inversion recovery (FLAIR) imaging, a technique that has recently become applicable in the clinical setting, as we help demonstrate in this series. With better MRI capability, milder forms of FCD and microdysplasia may be distinguished.

Transcutaneous vagus nerve stimulation for partial onset seizure therapy. A new concept.

A new concept for transcutaneous vagus nerve stimulation for control of partial onset seizures is described. The rationale for the application of this innovative noninvasive method is discussed.

The preoperative assessment in the planning of surgical management of medically refractory epilepsy in the pediatric patient.

Surgical intervention in refractory epilepsy in children offers the hope of seizure control. For the patient, the preoperative assessment is a major factor in whether he or she is selected as a patient who will potentially benefit. It also plays an important part in the choice of the surgical intervention to be used. This paper reviews the investigations available and suggests an investigational algorithm for use in the pediatric population.

Intracranial plasma cell granuloma.

Plasma cell granulomas (PCGs) are benign, inflammatory masses of unknown etiology composed of polyclonal mature plasma and lymphoid cells. The lung is their most common location, and occurrence within the cranial cavity is extremely rare. We report the case of an 11-year-old girl who presented with seizures and was diagnosed as having a dural-based right frontal tumor that extended toward the sagittal sinus and the falx. The lesion was totally excised, together with the abnormal dura. A limited cortical excision was also performed using electrocorticographic guidance. Histopathologic diagnosis of intracranial plasma cell granuloma was reached after extensive immunohistochemical tests and electron microscopy. This is the third case of PCG with description of changes in the neighboring cerebral tissue. Although PCGs are well-circumscribed lesions, lymphoplasmocytic inflammation, neuronal loss, and reactive gliosis occur within the adjacent cortex. Disturbed cortical lamination, as we have observed, appears to be a histological finding that has not been described previously.

Latex allergy in neurosurgical practice.

The possibility of latex allergy and the implications of the potential life-threatening allergic reactions among patients (for example those with spina bifida), health care professionals, and latex industry workers are discussed. Latex allergy is becoming increasingly widespread in medical and surgical practice. Although early reports of latex allergy date from 1927, only over the last decade has more attention been paid to this condition. This is due to an increasing number of reported cases of adverse reactions to latex, varying in severity from mild to fatal. Latex allergy has become a major problem in children with spina bifida, who need to undergo many major aggressive diagnostic and therapeutic procedures. Risk groups have been identified and include patients having multiple surgical procedures, such as those with spina bifida. In this review we aim to emphasise some aspects of the current management of surgical patients with latex allergy.

Hydrocephalus and epileptic seizures.

Is there an association between shunted hydrocephalus and the development of epileptic seizures? To answer this question a retrospective review of the medical records of 197 patients with shunted hydrocephalus was undertaken. In this series 17% of patients with hydrocephalus developed seizures. No correlation was found between the occurrence of epileptic seizures and a shunt malfunction, the number of shunts placed, the age of the patient at the initial shunt procedure or the location of the shunt. Patients with hydrocephalus who had significant cognitive delay or significant motor disability were significantly more likely to develop seizures than patients who did not. The findings of this review support the hypothesis that the occurrence of seizures in children with hydrocephalus is related to an underlying diffuse encephalopathy and not to the hydrocephalus or to procedures related to the treatment of this disorder.

Epidermoid cysts of the pineal region.

Localization of epidermoid cysts to the pineal region is rare. The 7-year-old boy now reported presented with an 18-month history of progressive ataxia. CT and MRI scans demonstrated a 2.5x2.5 cm cyst at the pineal region with obstructive hydrocephalus. At surgery via an occipital transtentorial approach, a characteristic "pearly tumour" was encountered, and complete resection was achieved. We present the management of this child with pineal region epidermoid cyst and review 11 cases reported in the literature since 1968. In all, 8 of the 12 patients were males. The age at the time of diagnosis ranged from 7 years to 69 years. Parinaud's syndrome and hydrocephalus are the most common presenting findings. All but 1 patient underwent direct surgical resection; 1 had stereotactic decompression. Surgical treatment brought about complete resolution of the presenting symptoms and signs in 10 of the 12 cases. One patient had persistent upgaze palsy. One patient died from progression of the pineal region mass. This patient presented with hemiparesis, which is a marker of clinical aggressiveness. The authors advocate direct surgical attack as opposed to stereotactic diagnosis and aspiration to: (1) obtain maximal resection and thereby limit the potential for recurrence and delayed complications of the cyst; (2) possibly avoid shunt placement in patients who present with hydrocephalus; and (3) decrease the likelihood of sampling error.

Predictors of seizure outcome following cortical resection in pediatric and adolescent patients with medically refractory epilepsy.

Several preoperative clinical variables have been reported to have value as predictors of seizure outcome following the surgical resection of epileptogenic focus in adults who have had medically refractory epilepsy. The present paper reports the results of a retrospective review of the ability of these variables to predict seizure outcome in a group of pediatric patients who had medically refractory epilepsy and underwent surgical resection of an epileptogenic focus at the Children's Hospital of Eastern Ontario. Variables in this review included age at first seizure, age at time of surgery, duration of seizures, seizure type, sex, family history, etiology, level of intelligence, EEG data, results of imaging studies, findings on examination of the central nervous system, and location and site of surgical resection. We found 64 patients who met the entry criteria for this review. Normal intelligence and tumor as etiology were associated with a good postoperative seizure outcome in patients who had a temporal resection; no variables had positive correlation with outcome in the extratemporal group. Caution must be used in the extrapolation of data and inclusion of studies of predictors of seizure outcome for adults to pediatric age groups.

Epilepsy surgery for 5- to 18-year old patients with medically refractory epilepsy--is it cost efficient?

This study was designed to examine the question of whether cortical resection for children and adolescents with medically refractory epilepsy was less costly and more effective than the medical alternative. The study design used a decision analysis model. Data on outcome probabilities were based on literature review and local experience. The time span of the study was 25 years. Though the initial costs for the surgically treated group were significantly greater than those for the medical group, the time-cost lines intersected at 14 years after surgery. Surgery remained cheaper thereafter.

Unusual association of intractable temporal lobe seizures and intracranial aneurysms in an adolescent: is it a coincidence?

Intracranial aneurysms in the pediatric age group are rare occurrences. They usually present with subarachnoid hemorrhage or mass effect. Their association with epilepsy has rarely been reported; such concurrence may not be a coincidence. We present a 16-year-old girl with a 5-year history of medically intractable complex partial seizures. Preoperative electrophysiological and neuroimaging studies demonstrated an epileptogenic focus and atrophy in the right mesial temporal lobe, and ipsilateral incidental aneurysm at the carotid artery bifurcation. The patient underwent a complete right anterior temporal lobectomy, followed by clipping of the aneurysm. We concluded that the epilepsy management in association with cerebral aneurysms is controversial, but when surgery is indicated, clipping of the aneurysm and resection of the epileptogenic focus may provide the optimal outcome. The relevant literature is reviewed and the possible mechanisms of production of epilepsy by intracranial aneurysms are discussed.

Long-term socioeconomic outcome following surgical intervention in the treatment of refractory epilepsy in childhood and adolescence.

Surgical treatment of refractory epilepsy in childhood and adolescence has been shown to be effective in reducing the seizure frequency. This paper examines the question: "Does this result in a better socioeconomic outcome in later years?" Patients who underwent a surgical procedure for the treatment of their medically refractory epilepsy at our hospital, had more than 2-years' follow-up, and were less than 18 years old at time of survey were included. From a retrospective chart review, age at onset and at surgery, duration of seizures prior to surgery, years of follow-up, type of surgery, and neurological status were obtained. From a telephone survey, seizure frequency after surgery, marital, financial and driving status, level of education, and employment status were ascertained. Sixty-four patients in our epileptic surgical series meet entry criteria. Significantly higher levels of education, employment status and independence were found in patients with a class I Engel outcome compared to other Engel outcomes.

Patient satisfaction with surgical treatment of refractory epilepsy done in childhood and early adolescence.

The results of a retrospective self-controlled telephone satisfaction survey of 63 patients who had undergone an earlier resection for the treatment of medically refractory epilepsy before the age of 18 years was reported. The survey items consisted of a global rating scale and a series of open-ended questions about positive and negative outcomes as a result of the surgery. Most (80%) of the patients felt the surgery had had a positive effect on their lives. The mean global score was 6.24+2.4 (scale 0-9). Strong positive correlations were found between seizure control and degree of satisfaction and between perceived postsurgical neurological deficits and dissatisfaction.