Charles Teo

Application of skull base techniques to pediatric neurosurgery

Abstract Techniques for skull base surgery have become well established over the last 10 years. Most of these techniques are used in adult patients for skull base tumors and neurovascular diseases. There are very few large series of pediatric patients in whom skull base approaches have been used, because of the rarity of these conditions. The authors would like to present a relatively large series of 26 pediatric patients who underwent skull base approaches for tumor resection. These tumors involved the anterior cranial base in 5 patients, the medial cranial skull base in 4 patients, and the posterior cranial base in 12 cases. Five patients had tumors that involved two or more fossae. The overall complication rate was 57%, which included temporary cranial nerve palsies, CSF leak and infection. Patients with permanent complications were 8 in number (37%). There was 1 postoperative death from pneumonia approximately 6 weeks after surgery. Complete tumor removal was achieved in 24 of the 26 patients. Skull base tumors in children are often extensive and present significant surgical challenges. Although complete tumor extirpation is the goal in most pediatric patients, this is often achieved only with some morbidity. This paper demonstrates the effectiveness of skull base approaches for these tumors and underscores the high stakes involved.

Telomeric associations in the progression of chromosome aberrations in pediatric solid tumors

Telomeric association (tas) is a cytogenetic phenomenon in which chromosome ends fuse to form dicentric, multicentric, and ring chromosomes. We observed clonal tas in six pediatric solid tumors of various types and histological grades studied using short-term in situ culture and G-banding techniques. These tumors included a neurilemoma, an undifferentiated (embryonal) sarcoma of the liver (UESL), two anaplastic astrocytomas (AA), one case of glioblastoma multiforme (GBM), and a neuroblastoma (NB) of the kidney. Cytogenetic data from all six tumors demonstrated multiple numerical and structural aberrations including tas. The tas appeared to be a secondary aberration in these tumors, however, it was possible to follow the progression of the telomeric chromosome aberrations in several cases. In all but one case (UESL) the loss of chromosome segments occurred. Tas of 11p was observed in three of the six tumors, two of which showed the subsequent loss of 11p (AA and AB). In addition, tas of 4p was seen in three tumors, two of which showed clonal tas of 4p with 22q. Tas of 10p, 21p, and 22q were all observed in at least two different tumors. The clonal telomeric fusions of 4p with 22q, recurring tas of 11p, and the subsequent loss of the short arm of 11 demonstrated here, suggests that some chromosome regions are subject to nonrandom instability and sometimes loss.

Application of endoscopy to the surgical management of craniopharyngiomas

ObjectiveThe purpose of this study was to evaluate the efficacy of a minimally invasive/endoscopic approach to craniopharyngiomas (CPGs) given that the surgical aim was a complete excision of the tumor as a single stage procedure. The endoscope can be used with both a subfrontal and a transsphenoidal approach.MethodsThis study is a retrospective review of 36 operative patients who were seen by one surgeon. All patients had attempted complete excision.ResultsPatients were divided into three groups according to their preoperative status. Those in group 1 had no previous treatment and fared well, although all developed postoperative diabetes insipidus. Those in group 2 had previous surgery only and also did well with repeat surgery. Those in group 3 had been treated previously with surgery and radiotherapy and, apart from a single exception, did poorly.ConclusionThe endoscopic, minimally invasive approach is versatile and effective in the surgical management of both first-time and repeat cases of CPG. It offers superior visualization of surrounding neurovascular structures and allows a more complete resection of tumor. It can be used for a cranial or a nasal approach to these tumors. Sadly, it failed to prevent postoperative endocrinopathy.

Endoscopic sublabial transmaxillary approach to the rostral middle fossa.

OBJECTIVE The rostral middle fossa faces the temporal pole and is the endocranial anterosuperior aspect of the greater wing of the sphenoid. Standard approaches to this region, such as the subtemporal, pterional, or orbitozygomatic approaches, require significant brain retraction or manipulation of the temporalis muscle. We report an endoscopic sublabial transmaxillary approach to this cranial base region that avoids the aforementioned pitfalls. METHODS Ten adult cadaveric half heads were used to develop the endoscopic approach and to identify the salient surgical landmarks. RESULTS The approach was divided into three stages: entry into the maxillary sinus, entry into the infratemporal fossa, and entry into the middle fossa. A craniotomy of greater than 20 mm in diameter can be safely created in the rostral middle fossa. When coupled with image guidance, the approach provides the flexibility to tailor the size and location of the middle fossa craniotomy. CONCLUSION Although endonasal endoscopic approaches are increasing in popularity, the middle fossa has not been adequately accessed with these techniques. The endoscopic sublabial transmaxillary approach provides safe and direct access to the rostral middle fossa, eliminating the need for brain retraction, temporalis muscle manipulation, or an external incision. The approach also permits early devascularization of cranial- or dural-based lesions.

The management of completely resected childhood intracranial ependymoma: the argument for observation only

IntroductionThe management of children with completely resected intracranial ependymomas is controversial. We favor deferring adjuvant radiotherapy in low-risk patients, whereas others recommend radiotherapy.ReviewThis article reviews the available evidence for and against deferring radiotherapy in children with low-risk completely resected childhood ependymomas.

Blindness, deafness, quadriparesis, and a retinal malformation: the ravages of neurofibromatosis 2☆

Advances in molecular biology have established that the diseases once collectively referred to as neurofibromatosis are actually genetically distinct and clinically heterogenous conditions. This realization has led to separate definitions for neurofibromatosis (NF) type 1 and 2. Although ophthalmologic manifestations of NF1 have long been recognized, the distinguishing ocular features of NF2 have only recently received attention. We describe an inferior retinopapillary malformation with an overlying glial hamartoma in a deaf, quadriparetic patient with NF2. Magnetic resonance (MR) imaging initially showed bilateral vestibular schwannomas and a large cervical ependymoma. Over six years of follow-up, the patient developed multiple intracranial meningiomas.

The Value of Endoscopy in the Total Resection of Pineocytomas

BACKGROUND Pineocytomas are rare pineal region tumors. The mainstay of treatment for pineocytomas is total surgical resection. OBJECTIVE To address the worthiness of endoscopy to achieve total macroscopic resection and whether or not this portends better progression-free and overall survival. METHODS A series of 15 patients (11 females, 4 males; mean age, 48 years) with histological diagnosis of pineocytoma were retrospectively reviewed. All patients underwent an attempt at total resection via an interhemispheric/transtentorial/retrosplenial approach. The endoscope was used at various times throughout the case and consistently at the end to evaluate any possible residual tumor. No patient in this series was given radiotherapy after surgery. RESULTS There was no surgical mortality and all patients are currently alive without recurrence (mean follow-up, 4.28 years). A macroscopic and radiological complete removal was achieved in all cases. There was only one patient with permanent neurological deficit (disconjugate eye movements). Two patients (13%) had transient poor sleep pattern, 5 patients (33%) had transient disconjugate eye movements, and 2 patients (13%) had transient short-term memory disturbance. In 6 cases (40%), the endoscope was able to detect residual tumor located either behind the Vein of Galen or attached to the undersurface of the corpus callosum. Residual tumor was then resected using a 30° endoscope and dedicated angled endoscopic instruments. CONCLUSIONS This series demonstrates the advantage of endoscopic-assisted surgery in the total removal of pineocytomas. With total removal of these histologically benign tumors patients may enjoy extended progression-free survival without adjuvant radiotherapy.

Spontaneous third ventriculocisternostomy in an infant with obstructive hydrocephalus

Spontaneous ventriculocisternostomy, the spontaneous communication between the ventricular system and the subarachnoid space, is rare. The authors report a case of an infant with obstructive hydrocephalus who developed a spontaneous third ventriculocisternostomy. The infant was initially evaluated for progressive ventriculomegaly and increasing head circumference (HC). During follow-up, the patients HC began to follow percentile lines and magnetic resonance (MR) imaging demonstrated a reduction of the hydrocephalus. Flow-sensitive phase-contrast cine MR images revealed cerebrospinal fluid (CSF) flow through the floor of the third ventricle between the tuber cinereum and the mammillary bodies connecting the ventricular system with the prepontine cistern. Although rare, clinicians should be cognizant of this phenomenon as it may eliminate the need for CSF diversion.

Neurenteric cyst: an unusual cause of third nerve palsy

IntroductionNeurenteric cysts are a rare cause of central nervous system compression. Pediatric intracranial cysts are even less common.Case studyWe describe the presentation, imaging features, surgical management, and postoperative course of a 5-year-old female with congenital third nerve paresis, worsening headaches, and a cyst of the third nerve. We performed an eyebrow incision and keyhole supraorbital craniotomy for exploration and subsequent resection of a neurenteric cyst that was densely involved with the third nerve at its exit from the midbrain. Postoperatively, she had chemical meningitis and complete third nerve palsy. This entity is extremely rare in this location but should be included in the differential. We summarize the current literature on these lesions and recommend biopsy and fenestration as surgical treatment.

Low-Grade astrocytoma with a complex four-breakpoint inversion of chromosome 8 as the sole cytogenetic aberration

We report a case of a low-grade astrocytoma in a 10-year-old boy in which the sole cytogenetic aberration was a complex four-breakpoint inversion of chromosome 8 with the karyotype designation 46,XY,der(8)inv(8)(p23q24)inv(8)(q11q21). Two protooncogenes on chromosome 8, MOS at 8q11 and MYC at 8q24, are located at or near the bands which correspond to two of the breakpoints in this inversion. The localization of the structural aberrations to four breakpoints on chromosome 8 provides a rare example of a solid tumor with structural aberrations limited to a single chromosome.