Surgical implications of cerebral dysgenesis

Cerebral dysgenesis encompasses varied disorders of brain development. Based on the understanding of these conditions provided by histopathologists, embryologists, radiologists and developmental pediatricians, surgeons are able to appropriately assist in the care of these patients. The surgeon can offer assessment of the ventriculomegaly that commonly accompanies cerebral dysgenesis in addition to providing methods to control hydrocephalus, to reconstruct cranial and facial malformations and to remove dysfunctional tissue. For most patients, surgical intervention is only one of the many factors that determine developmental prognosis. Based on the foundation built by other specialists, this review discusses cerebral dysgenesis from the perspective of historical and current surgical interventions.

Early computed tomographic scanning after resection of brain tumors in children

Enhanced and non-enhanced computed tomography (CT) brain scans were performed within 72 h of surgery on 21 children in whom brain tumors had been resected totally or subtotally, and scans were repeated at varying intervals thereafter. Biopsies of the resection margins were performed in 12 patients at the end of the surgical procedure. The immediate CT scan showed enhancement in the resection margin in 13 of the 21 patients and in 9 of the 13, the enhancement disappeared on follow-up scans. There was discordance between the results of immediate CT scan examination and the biopsies of the resection margins in 7 of the 12 cases. The advantages and disadvantages of an immediate postoperative scan versus a more delayed CT scan are discussed.

Cervical neuroschisis and meningocoele manque in type I (no neck) Klippel-Feil syndrome

A male child with type I (no neck) Klippel-Feil syndrome presented at birth with a transient and partial cord injury. Investigations failed to reveal spinal instability or foramen magnum compression. Subsequent deterioration led to investigations that demonstrated neuroschisis. A cervical meningocoele manque with cord tethering was found at exploration and untethering reversed the deficit. The surgical pathology of the cervical cord is described.

Ruptured intracranial aneurysm presenting as cerebral infarction in a young child

We describe a 15-month-old girl who presented with an acute hemiplegia. The sequence of events appears to have been clinically silent subarachnoid hemorrhage, vasospasm, infarction and a second lethal hemorrhage 3 months later. The old infarction was seen on computed tomography during her second illness. Autopsy confirmed the presence of a recent rupture of an intracranial aneurysm and old hemorrhage. In addition there was an unusual fibroblastic proliferation in the aneurysm wall. This case demonstrates that clinically silent subarachnoid hemorrhage, vasospasm and infarction can occur as complications of aneurysms, even in very young children.

Apnea in patients with myelomeningocele

Apnea is a known complication of the Chiari II malformation presenting in infancy. Obstructive apnea secondary to bilateral abductor palsy or laryngomalacia and centrally mediated expiratory apnea with cyanosis can occur. Observations of 9 patients suggest that these forms of apnea may represent stages in a continuum of brain stem dysfunction due to the combined effects of the hindbrain malformation and its compression, hydrocephalus and progressive arachnoiditis. Obstructive apnea in some patients may be reversed by optimal control of hydrocephalus with or without cervical decompression. These patients may also develop episodes of cyanotic expiratory apnea of central origin (PEAC). This form of apnea does not respond to surgical or medical treatment and may show progressive worsening over time. Five of 6 patients with this form of apneic spell died suddenly, 2 of these died despite full recuscitative efforts. It is recommended that reports of treatment address results for both forms of apnea.

Keyhole craniectomy for correction of sagittal synostosis

A modification of the technique combining sagittal strip, circular occipital and biparietal wedge craniectomies (Albright's procedure) for the treatment of sagittal synostosis, with prominent occipital bossing, is described. "Keyhole," as opposed to wedge, parietal craniectomies allow improvement in the shape of the skull, beginning intraoperatively, while eliminating the outbending of the parietal bone that occurs at the apex of a wedge craniectomy.

Spontaneous remission of paralysis due to spinal extradural hematoma: case report

Spontaneous spinal extradural hematoma is an uncommon cause of cord compression and paraplegia. The clinical presentation of this entity is uniform, with sudden pain followed by sensory and motor dysfunction. Unlike other considerations in the differential diagnosis of cord compression, here the pain and clinical deficit may remit suddenly and spontaneously. This feature may obscure the diagnosis of an organic cause for cord dysfunction. This report describes a patient whose extradural hematoma was caused by hemorrhage from an arteriovenous malformation. Dramatic reduction of his pain and paralysis followed myelography.

Neurotoxic complications of contrast computed tomography in children

Four children with brain tumors had marked alterations in levels of consciousness and vital signs after contrast-enhanced cranial computed tomography (CT). Each had clinical evidence of increased intracranial pressure but was alert and coherent before CT. During the procedure, 2 to 2.5 mL/kg 60% diatrizoate meglumine was administered intravenously, and within hours the patients became progressively lethargic and disoriented and bradycardia and hypertension developed; two had generalized seizures. Two children died immediately after the CT procedure. Contrast-enhanced CT may produce grave neurologic complications in children with brain tumors, and this study should be reserved for those patients in whom the probability of obtaining additional information is high. Use of low-osmolality agents or nonionic contrast agents may decrease the morbidity and mortality associated with the procedure.

Visual evoked potentials, intracranial pressure and ventricular size in hydrocephalus

Hydrocephalus in the newborn is frequently seen associated with perinatal asphyxia, birth trauma, or intracranial hemorrhage. Hydrocephalus produces enlargement of the cerebral ventricles and raised intracranial pressure secondary to increases in the amount of cerebrospinal fluid. In this study the relationship between the visual evoked potential and ventricular size in infantile hydrocephalus was investigated. Statistical analysis was used to define them and the role of the visual evoked potential in the clinical and structural assessment of infantile hydrocephalus. The results of these investigations demonstrated a significant relationship between ventricular size and evoked potential parameters and confirmed the usefulness of the flash visual evoked potential examination in the assessment of infants with hydrocephalus.

Maturational topography of the visual evoked potential in fetal lambs

The normal maturational course of the visual evoked potential (VEP) in human newborns and infants is well documented. Unfortunately, there is a paucity of data about VEP maturation in the 'normal' preterm infant. Since this population is at risk to develop many abnormalities affecting the VEP (intraventricular hemorrhage, hydrocephalus, and retinopathy of prematurity), one must question whether such VEP data collected from this group is representative of normal maturation. To provide normative parametric developmental data we have been studying VEP development in fetal lambs. Six fetal lambs between 105 and 120 days gestational age were externalized and surgically instrumented with subcutaneous recording electrodes placed over the occipital and parietal regions. High-intensity light-emitting diodes (LEDs) externalized fiberoptic cables were secured adjacent to the orbit. from 108 to 141 days gestation, fetal VEPs were recorded in response to bright flash stimulation and the maturational topography was investigated. Over the occipital regions, the emergence of major positivities at P400 and P650 were observed beginning around 120 days gestation. Over the parietal area, the emergence of P200 and P500 components was observed by 128 days gestation. The latency-maturation functions revealed that the slope of the parietal function was steeper than the occipital counterpart, suggesting that the maturation of parietal neurons occurs at a faster rate than neuronal development in the occipital regions.

The application of i.v. digital subtraction angiography to cranial disease in children

All intracranial IV digital subtraction angiographic examinations performed over the past 2 years were reviewed retrospectively to ascertain the uses and limitations of this technique for the evaluation of pediatric intracranial disease. Of the various abnormalities studied, this imaging technique was particularly useful in diagnosing venous and dural sinus abnormalities; in screening for suspected large aneurysms, vascular malformations, and major arterial occlusive disease; and in preoperative vascular mapping. IV digital subtraction angiography has selected usefulness in confirming brain death, in evaluating cerebral ischemia, in identifying vascular abnormalities underlying intracranial hemorrhage, and in evaluating vascularity and sinus extension of masses. The IV route for digital subtraction angiography is not useful in diagnosing segmental arterial occlusive or small-vessel disease, nor is it useful in preoperative localization of specific arterial supply to arterial venous malformations, aneurysms, or neoplasms. IV digital subtraction angiography can be performed successfully in children of all ages with minimal patient morbidity. For most patients, the diagnostic information obtained was adequate without the need for standard cerebral arteriography.

Intrauterine hydrocephalus and ventriculomegaly: associated anomalies and fetal outcome

Advances in fetal diagnostic techniques have opened many areas to prenatal anatomical scrutiny. Intrauterine hydrocephalus and ventriculomegaly are conditions which are readily diagnosed. Fetal intervention has been undertaken in humans in order to minimize the craniofacial disfigurement and to maximize the growth potential of the brain. To justify such an approach, the significance of all anomalies should be recognized prior to treatment. The authors have reviewed 41 cases of hydrocephalus diagnosed in utero in order to define associated anomalies and patient outcome. 75% of our personal series and 72% of the reviewed literature cases had other anomalies of the central nervous system. Other system malformations, some of which proved fatal, were seen commonly. Prenatal diagnostic techniques did not always reveal these additional problems. The outcome of these pregnancies is not good. Approximately one third of these fetuses have survived to be treated postnatally and to be followed up clinically. Only 7.5% of this series were felt to have attained normal developmental milestones. The remainder of the survivors have various focal and/or global cerebral deficits.

Management of intrauterine hydrocephalus

The aggressive treatment of hydrocephalus has been of benefit to many children. Sophisticated two-dimensional ultrasound techniques allow the diagnosis of prenatal hydrocephalus to be made with accuracy and ease. In the past, the medical decisions governing the management of hydrocephalus in utero were made by obstetricians and were directed at reducing maternal mortality and morbidity. Now, with improved diagnosis and support facilities for the newborn, neurosurgical input is being requested as more concern is expressed for the fetus. Based on their experience with seven cases of intrauterine hydrocephalus in the past 3 years, the authors present their program for the management of this problem. If antenatal ultrasonography shows hydrocephalus without other anomalies, they recommend that the fetus be born by elective Caesarean section at the time of pulmonary maturity, and that early ventricular shunting be carried out. This plan should minimize nervous system trauma resulting from hydrocephalus and the birth process. If, however, antenatal diagnostic studies show cerebral or other major system anomalies in addition to hydrocephalus, than standard obstetrical care should be given. Antenatal ultrasonography has been found to be reliable in assessing fetal lateral ventricular size and shape, and to correlate well with the results of postnatal computerized tomography scanning.

Clinical - radiological correlates in intracerebral hematomas due to aneurysmal rupture

In this series of intracerebral hematomas from aneurysmal rupture, gathered from several neurosurgical services, certain morphological features were studied in detail. Patients with very large hematomas tended to have poor neurological grades on admission to hospital and their immediate discharge outlook was correspondingly poor. Ruptured middle cerebral and pericallosal artery aneurysms were relatively common causes of intracerebral hematomas. Patients with temporal lobe hematoma did relatively well; those with parietal hematoma did poorly. The larger the hematoma the less chance there was of developing cerebral vasospasm but the more likely was pre-operative brain herniation. The survival was more closely linked to size and location of the hematoma than to the location of aneurysm or the degree of midline shift.