Harold J. Hoffman

The Tethered Spinal Cord: Its Protean Manifestations, Diagnosis and Surgical Correction

31 children with spina bifida occulta who have presented with back pain, scoliosis, a progressive neurological deficit involving lower limbs or a neurogenic bladder have been found to have a tethered spinal cord. Release of the tethered spinal cord has always relieved pain, frequently occrected a progressive scoliosis, and arrested or improved neurogenic foot deformities as well as neurogenic bladder.

Arteriovenous malformations of the brain in children : a forty year experience

Despite the great capacity for the pediatric brain to recover from stroke, the morbidity and mortality in children who harbor an arteriovenous malformation (AVM) remains high. This study examines the clinical data and management experience with 132 patients with brain AVM from 1949 to 1989. Although the high tendency for a childhood AVM to present with hemorrhage (79%) remained constant for the forty year study period, the associated morbidity and mortality of hemorrhage changed. The mortality rate from hemorrhage for the entire series was 25%, which was reduced from 39% to 16% after the introduction of computed tomography. The mortality from AVM hemorrhage since 1975 was dependent on location; 8 of 14 patients (57%) with a cerebellar AVM died from hemorrhage while only 2 of 44 patients (4.5%) with a cerebral hemisphere AVM died (p less than 0.0001). Sixteen children (12%) presented with a chronic seizure disorder. Surgical excision of the malformation resulted in complete seizure control off anti-convulsant medication in 73% of patients. Although 21% of patients were treated non-operatively (many with terminal poor-grade hemorrhage), 79% had a surgical procedure with total AVM excision achieved in 70 patients (53.1%). Complete AVM resection was followed by a normal neurological outcome in 47 children (67%). Most partial excisions (n = 9) and clipping of feeding arteries (n = 7) were performed in the early years of this study, and did not provide protection from rehemorrhage. Although conservative management has been advocated for selected non-hemorrhagic AVMs, we conclude that essentially all children with an AVM should be treated in order to eliminate the risk of hemorrhage.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Stem Gliomas: A Classification System Based on Magnetic Resonance Imaging

MR scans of 87 pediatric patients with brain stem gliomas were retrospectively reviewed to develop a new classification scheme based on MR imaging. The scheme that has been developed utilizes primarily T2-weighted images, as these most accurately show tumor extent. Tumors are characterized as to location of origin, focality, direction and extent of tumor growth, degree of brain stem enlargement, degree of exophytic growth, and presence or absence of cysts, necrosis, hemorrhage, and hydrocephalus. The use of this classification allowed identification of differences in a population of patients who were selected to be as similar as possible. This system will aid in the assessment of new protocols for treatment of brain stem tumors.

Extraneural metastases of central nervous system tumors.

In the past, extraneural metastasis of central nervous system tumors was considered to be a rare event. However, more recently, a considerable body of literature has accumulated so that to date some 282 patients with extraneural metastases have been reported. Of these reported cases, 40.4% have occurred in children. Although central nervous system tumors can spread spontaneously beyond the confines of the central nervous system, most instances of extraneural metastasis occur after craniotomy or diversionary cerebrospinal fluid shunting. Extraneural metastases are universally fatal. Although it is not curative, chemotherapeutic treatment of metastases may greatly decrease the patients discomfort and improve the quality and duration of survival. Every effort should be made to prevent this complication by avoiding diversionary cerebrospinal fluid shunting procedures or by incorporating a filtering device if a shunt becomes necessary. Cancer 56: 1778‐1782, 1985.

Development of Anaplastic Changes in Low-Grade Astrocytomas of Childhood

The authors present their experience with six children who developed anaplastic astrocytomas after receiving treatment for low-grade astrocytomas. Five children were from a series of 55 children with optic chiasmatic-hypothalamic gliomas who have been studied since 1976. The sixth child initially had a low-grade astrocytoma of the thalamus. The mean age of the children at initial presentation was 5.3 years. Five children were treated with surgery and radiation therapy; one child with a chiasmatic-hypothalamic glioma received radiation therapy alone. The amount of external radiation therapy used in all children was 50-52.5 Gy delivered in standard fractionations over approximately 6 weeks to include the volume of the original tumor plus a margin of 2 cm. The time to anaplastic transformation varied between 2 and 10 years (mean, 6.4 years). At tumor recurrence, the children had seizures or symptoms and signs of raised intracranial pressure. The location of the second tumor in all patients was either at the primary site or within the field of radiation therapy. Five of the six children underwent a second craniotomy and subtotal resection of their malignant gliomas. One child had positive cerebrospinal fluid cytology and multiple intraspinal metastatic tumor nodules detected by magnetic resonance imaging. On histopathological examination, four children had anaplastic astrocytoma, and two had glioblastoma multiforme. Four of the six children have died of their anaplastic astrocytomas (mean time from diagnosis of anaplastic astrocytoma to death, 10 months). Two children underwent chemotherapy and spinal irradiation for their anaplastic astrocytomas, and are currently alive and undergoing treatment. The possible mechanisms by which anaplastic tumors have developed in children treated previously for low-grade astrocytomas is discussed. The data suggest that radiation therapy may have played an integral role in the genesis of anaplastic astrocytomas in these children.

Surgical Management of Children with Temporal Lobe Epilepsy and Mass Lesions

In a review of 48 children who underwent temporal lobectomy for temporal lobe epilepsy, 16 patients had mass lesions in the temporal lobe. These mass lesions consisted of 12 tumors, 3 vascular malformations, and 1 arachnoid cyst. In 9 of 10 patients where the hippocampus was present in the pathological specimen and was not involved by tumor, there was concomitant mesial temporal sclerosis. All 16 patients have been followed for more than 1 year. Nine are free of seizures, with 4 of these 9 still on medication. Seven patients have had a greater than 50% reduction in seizures.

Posterior fossa medulloblastoma in childhood: Treatment results and a proposal for a new staging system

Seventy-two children with posterior fossa medulloblastoma were diagnosed at the Hospital for Sick Children, Toronto, from 1977 to 1987 and treated by standard methods. The 5- and 10-year survival and disease-free survival rates were 71% and 63%, and 64% and 63%, respectively. Total tumor resection, as determined by the surgeon was the most significant favorable prognostic factor. Post-operative meningitis, a residual enhancing mass lesion on the post-operative, pre irradiation CT scan and dissemination to the brain or cord at diagnosis were unfavorable factors. These four easily definable factors were used to define a staging system with prognostic significance. Five-year disease-free survival rates were for Stage I (total resection, no adverse factor) 100%, Stage II (total resection with one or more adverse factor or less than total resection with no other adverse factor) 78%, and Stage III (less than total resection with one or more adverse factor) 18%. Evaluation of treatment results in medulloblastoma requires that these prognostic factors be known.

The Tethered Spinal Cord

The tethered spinal cord includes a group of dysraphic conditions in which the conus medullaris is located in an abnormally low position and is fixed there in a relatively immobile state. During fetal life, the spinal cord grows much more slowly than the vertebral column. This leads to a progressive disparity between the termination of the spinal cord and the termination of the spine, in effect to a progressive ascent of the conus medullaris. Barson’s studies showed that in the 20-week embryo, the conus medullaris terminated at the L4–5 level.1 By term, the conus had ascended to L3 and by two months of postnatal age, the conus reached the adult Ll–2 level (Fig. 9.1). Tethering of the conus prevents this normal ascent. Yamada–s studies have conclusively shown that if stretch is placed on the conus medullaris, progressive ischemia occurs, leading inevitably to neurologic sequelae.2

Combined utility of functional MRI, cortical mapping, and frameless stereotaxy in the resection of lesions in eloquent areas of brain in children.

We studied 16 children with lesions in the eloquent brain to determine if the amalgamation of information from functional magnetic resonance imaging (fMRI), frameless stereotaxy, and direct cortical mapping and recording could facilitate the excision of these lesions while minimizing potential neurological deficits. The mean age of the children was 10 years. Fourteen children presented with seizures. All lesions were located in or near eloquent cerebral cortex. fMRI was successful in all patients in delineating the relationship between the lesion and regions of task-activated cortex. The ISG wand was utilized in all cases for scalp and bone flap placement, and for intraoperative localization of the lesion. Direct cortical stimulation or recording of phase reversals with somatosensory evoked potentials helped delineate the central sulcus and language cortex in patients with lesions near the motor or language cortex. Intraoperative electrocorticography (ECoG) was utilized in all patients who presented with seizures to guide the extent of resection of the epileptiform cortex. Ten children had benign cerebral neoplasms, nine of which were totally resected. The other diagnoses included vascular malformations, Sturge-Weber, tuberous sclerosis, Rasmussens encephalitis, and primitive neuroectodermal tumor. Only 1 patient with a left Rolandic AVM developed a new neurological deficit postoperatively. Thirteen of fourteen patients who presented with seizure disorders were rendered either seizure free or improved in terms of seizure control postoperatively. Follow-up has ranged from 12 to 18 months, with a mean follow-up of 15 months. We conclude that the techniques of fMRI, frameless stereotaxy, direct cortical stimulation and recording can be utilized in sequence to accurately localize intracerebral lesions in eloquent brain, and to reduce the morbidity of resecting these lesions in children.

Hemispherectomy for Sturge-Weber syndrome.

Patients with Sturge-Weber disease who have the onset of seizures in infancy invariably face a progressively downhill course which leaves them severely hemiplegic, demented and usually institutionalized because of uncontrolled seizures. During the past 12 years, we have carried out 6 hemispherectomies in infants under 1 year of age who presented with seizures and Sturge-Weber disease. The results have been gratifying. Seizures have stopped, hemipareses have been minimal and intellectual development has been good.