Parallel and serial search in two teenagers with lesions of the mesial parietal cortex.

Visual-spatial attention was examined in two 14-year-olds who had undergone occipital-parietal craniotomies for removal of mesial parietal tumors, one in the right and one in the left hemisphere. Neither patient showed clinically significant visual neglect. They were administered two visual search tasks from Treisman and Souther [43] that make significantly different demands on visual spatial attention. In feature-present (parallel) search, they searched for the presence of a feature. In feature-absent (serial) search, they searched for its absence. Search rate was estimated from the slope of the function relating display size to response time. Both patients had flat slopes in feature-present search to target-present (TP) displays, indicating that they could conduct parallel search at the same rate as controls. Although the patient with the right-hemisphere lesion also had a flat slope to target-absent (TA) displays, the patient with the left-hemisphere lesion had a steep slope (30 ms/item) in this condition. In feature-absent search, the patients had equally slow search rates compared to controls, suggesting that the mesial parietal cortex is part of the network that mediates serial shifts of attention. Results support the distinction between detection of the target in parallel vs serial search and suggest that processes involved in TP and TA trials in parallel search are also dissociable.

Neuroamine related compounds in the CSF of hydrocephalic rabbits.

The effects of neonatal hydrocephalus on the levels of tyrosine, tryptophan, 5-hydroxyindoleacetic acid (5-HIAA), and homovanillic acid (HVA) in CSF were determined by high-performance liquid chromatography (HPLC) with fluorometric detection in normal and chronically hydrocephalic rabbits. The hydrocephalic rabbits showed a highly significant increase in both the serotonin metabolite 5-HIAA and the dopamine metabolite HVA. There were no significant effects of the hydrocephalus on either tyrosine or tryptophan levels. There was a significant positive correlation between the intracranial pressure (ICP) and the increase in 5-HIAA and HVA, but not with the two precursor amino acids. There was a significant decrease in these amino acid precursors with age in both groups. A trend towards higher levels of 5-HIAA and HVA in older rabbits was also evident, however this change was not to the degree found in the hydrocephalics. These data indicate that increased ICP affects the mechanism of removal of 5-HIAA and HVA from the cerebrospinal fluid.

Limited selective posterior rhizotomy for the treatment of spasticity secondary to infantile cerebral palsy: a preliminary report.

A limited selective posterior rhizotomy was performed on 30 children suffering from spasticity secondary to infantile cerebral palsy. As opposed to standard techniques that stimulate and divide the dorsal rootlets from L2 to S1, we dissected L4, L5, and S1 dorsal roots through an L5 to S1 laminectomy. Eight to 12 rootlets from each root were electrically stimulated with two unipolar electrodes (pulse width, 50 microseconds; 10-50 V). The muscle responses were observed visually and registered by electromyography. Those rootlets associated with an abnormal motor response as evidenced by sustained muscular contraction or by prolonged electromyographic response were divided. Spasticity was scored from 0 to +. The muscular groups assessed were those involved in the flexion of the shoulder, elbow and wrist in the upper limbs, and those involved in flexion and adduction of the hip, flexion of the leg, and plantar flexion in the lower limbs. The patients were assessed 1 week before and 6 months after the operation. Reduction of spasticity was observed in all the muscular groups, and all the patients presented functional improvement of motor abilities. These preliminary results indicate that a limited procedure that reduces the extension of the laminectomy and the length of the operation could be effective for treating spasticity secondary to infantile cerebral palsy.

Pediatric low-grade gliomas: prognosis with proton magnetic resonance spectroscopic imaging.

OBJECTIVE: Our aim was to assess the correlation between the low-grade glioma (LGG) metabolic profile and tumor progression. Using in vivo proton magnetic resonance spectroscopic imaging, we specifically asked whether and which metabolic features are associated with tumor regrowth or recurrence. METHODS: Eleven pediatric patients with histologically proven partially resected (<20% resection) midline LGG were treated and followed up for a period of 2 years. All patients underwent proton magnetic resonance spectroscopic imaging studies before any management was determined. Tumor progression was defined as radiological evidence of mass enlargement (>25%) during the follow-up period. Proton magnetic resonance spectroscopic imaging was performed using a PRESS-CSI sequence on a General Electric 1.5-tesla scanner (General Electric Medical System, Waukesha, WI). The signal intensities of N-acetylaspartate, choline (CHO), and creatine from the tumor and the normal brain were used to calculate normalized metabolite intensities and metabolite ratios. RESULTS: Tumors that progressed during a 2-year period displayed higher normalized CHO than those that remained stable (Mann-Whitney test, P < 0.03). The majority (five of six) of the rapidly growing LGG showed values of normalized CHO of at least 1, whereas the nonprogressors had a normalized CHO value of less than 1. CONCLUSION: In association with pediatric LGG, high normalized CHO values seem to herald the potential for rapid tumor growth. These observations may be valuable for defining subsets of patients with LGG who may benefit from early therapeutic interventions.

Relevance of the cerebellar hemispheres for executive functions.

The aim of the present study was to elucidate the role of the cerebellar hemispheres in executive functions. The findings are relevant because of the large number of children who survive cerebellar tumors. Neuropsychologic assessments of four patients (8-21 years of age) who had undergone neurosurgery for removal of tumors in the cerebellar hemispheres were conducted and compared with the assessments of six children who had been diagnosed with temporal lobe tumors or cysts. The executive functions were assessed using the Wisconsin Card Sorting Test. IQs were average in both groups. As expected, patients with cerebellar hemispheric lesions had impaired executive functions. In particular, they appeared to have difficulty generating and testing hypotheses regarding the matching rules on the Wisconsin Card Sorting Test. Patients with temporal lesions had a different pattern of deficits on this test. The findings are consistent with the theories that propose that the cerebellar hemispheres are involved in cognitive processes. The findings also demonstrate that subtle deficits in executive functions can be masked by a normal IQ in survivors of cerebellar tumors and highlight the need to design interventions targeted toward problem-solving skills.

Short-term and procedural memory for colours and inferior temporal cortex activity.

Two children (male, 10 years, and female, 13 years one month) with tumours of the inferior temporal (IT) cortex of the brain were studied post-surgically for their abilities to carry out a short-term memory test. This involved: differences in colour, number and shape of small plastic objects; differences in receptacles where these objects should be placed and in ways in which this placement should be done; a procedural task involving differences either in colour or in size of wooden rings employed in the task. Their performances in these tests, and those of patients with tumours of other encephalic areas, were compared with the performances of normal controls. The subjects with IT tumours spent a significantly greater amount of time than normal subjects of their age in carrying out the procedural task involving differences in colour. One of the IT subjects also spent a significantly greater amount of time in the procedural task involving size differences. Other differences in the performances of patients with encephalic tumours and the performances of normal controls were not significant. Results are discussed in relation to findings of colour and size perception and memory localized to the inferior temporal and middle temporal cortices.

A probe for simultaneous sampling in stereotactic brain biopsy. Technical note.

A probe for stereotactic brain biopsy which allows to obtain two different samples along a single trajectory tract is presented. It consists of a cylindrical stainless steel probe which has two separate grooves. The pieces of tissue are shredded from the lesion by sliding a polyethylene cannula that fits around the probe.

Spinal tumours of childhood.

Spinal tumours in children have different features and require different management than in adults; 20 patients under the age of 14 years are reported--the common presenting features were limb weakness, pain and spinal deformity. Eight tumours were extradural and 12 intradural of which 3 were intramedullary. The 6 patients who did not do well postoperatively were found to have a malignant tumour or were completely paraplegic or quadriplegic before surgery. If detected and treated early, results are excellent in many cases, since the tumours are usually benign.

Preoperative and postoperative analysis of visual and auditory memory in children with cerebellar tumors.

Motivated by the extensive clinical and experimental evidence that links the cerebellum to cognitive processes, we analyzed the auditory and visual memory of nine children with cerebellar tumors. Five patients had midline lesions and four had cerebellar hemispheric tumors. The patients were tested before and after surgery. One of the patients was also tested at 4 and 24 months after surgery. A third group constituted by four children, siblings of some of the patients, served as control. Statistically significant differences (P < 0.05) were found in the test of auditory memory, in which children with cerebellar tumors made a higher number of errors than their normal counterparts. Surgery performed according standard techniques did not increase significantly the number of errors in any of the tested categories. Location of the tumor (hemispheric vs midline) was not a determinant of the performance of the children. The patient tested up to 2 years after surgery demonstrated a progressive improvement in the performance of visual and auditory memory tasks. Our results provide further evidence that the cerebellum plays a role in the integration of auditory stimuli.

[Chiari malformation]. / Malformación de Chiari.

The Chiari malformation (CHM) is a congenital disease of unknown etiology. It is presumed that a defective closure of the neural tube produces at least one of its three types. It has also been related to traumatic delivery. Type II is closely associated to the myelomeningocele. The clinical picture is determined by the chronic compression of the cervical cord by the cerebellar tonsils. Low cranial nerve palsy and muscular hypotonia are some of its predominant features. Syringomyelia complicates type I. CAT scan and NMR are the preferred radiological studies for diagnosing MCH. Treatment is surgical. Posterior fossa decompression and cervical laminectomy are sufficient if the ventricular shunt is patent. If treatment is installed before permanent structural damage is present, up to 88% of the patients have significant remission of the symptoms.

The probable role of hydrocephalus in the development of intraventricular septa. An observation of one case.

Multiloculated cerebral ventricles are a well-known complication of neonatal meningitis secondary to gram-negative bacteria. Their presence often hampers the proper functioning of the multiple shunts required for draining the ventricles. To determine whether the associated hydrocephalus may contribute to the development of the ventricular septa, we analyzed the histological structure of the ventricular wall and of the ventricular septa of a child who died as a consequence of Escherichia coli meningitis and unilateral hydrocephalus. Our results show that the ventricular septa are formed by glial protrusion into the ventricles. The ependymal wall of the grossly dilated ventricle was disrupted, but not that of the contralateral ventricle. We hypothesize that the presence of an insufficiently controlled hydrocephalus may have been one of the factors that induced the formation of the septa. It is suggested that an external ventricular derivation should be used during the active phase of the infection.

[Lumbar dermal sinus as a cause of intramedullary and subdural abscess. Report of 2 cases]. / Seno dermoide lumbar como causa de absceso medular y subdural. Informe de dos casos.

Dermal sinus is a congenital lesion more frequently presented in the lumbar area. Produces tethering of the spinal cord and its presence increases the risk of infections of the CNS. The only treatment of those lesions should be neuro-chirurgical: the goal of the surgical procedure is to remove the lesion and to free the spinal cord from its attachment to the surrounding layers. Magnetic resonance is the ideal diagnostic procedure. We report two cases of children of ten months and one year old harboring a congenital dermal sinus complicated respectively with intramedullary and subdural abscess. Prompt surgical treatment allowed regression of the symptoms. The MR images are detailed.

Intradural neurenteric cyst at the craniovertebral junction.

A case of an intraspinal neurenteric cyst at the craniovertebral junction in a 7-year-old girl is reported. The intermittent progression of her neurological symptoms delayed the diagnosis. The location and cystic nature of the lesion were diagnosed with magnetic resonance imaging. Total surgical excision of the cyst was possible.

Acute spinal cord swelling in a child with Chiari II malformation.

We report on a patient with Chiari II malformation who developed acute cervical myelopathy and brainstem dysfunction following a shunt failure. A brain and spine magnetic resonance image obtained immediately after admission evidenced swelling of the medulla and upper cervical spinal cord. After emergency placement of an external ventricular drain, the swelling receded, the child's respiratory pattern improved and the motor function of his upper and lower extremities progressively returned to its normal condition. The case reported here suggests that in patients with Chiari type II malformation, spinal cord swelling might have a similar pathophysiology to the periventricular edema observed in the supratentorial compartment, and thus may be independent of the early stages of syringomyelia or syringobulbia.

Variation of post-treatment H-MRSI choline intensity in pediatric gliomas.

Pediatric brain gliomas are not always amenable for complete surgical excision, therefore adjuvant treatment for a large tumor mass is often required. As tumor volume shrinkage may not be a reliable method for assessing response to treatment, information about the tumor growth potential is desirable for an adequate follow-up of the patients. Choline (Cho) signal intensity, determined by proton magnetic resonance spectroscopy imaging (H-MRSI), has proved to be a reliable indicator of the metabolic activity and of tumor progression in various intracranial tumors. In this study we have sought to determine if H-MRSI can be of use in monitoring the response of pediatric gliomas to different forms of therapy. We performed pretreatment and post-treatment H-MRSI in 10 children with biopsed or partially excised brain gliomas. The follow-up period ranged between 6 and 40 months. A total of 38 H-MRSI were performed. All the patients had chemotherapy or radiotherapy. As an indicator of tumor activity we utilized the ratio between tumor/brain Cho signal intensity. Treatment response was evaluated as a function of tumor volume and clinical outcome. In 6 patients whose tumor volume decreased or remained stable we observed that the Cho ratio decreased (p < 0.01) after treatment and remained low during longitudinal follow-up. In the 4 patients whose tumors progressed the Cho ratio increased after treatment. These observations suggest that serial H-MRSI can provide valuable information regarding the response to therapy in pediatric gliomas and therefore be of use in the follow-up of these neoplasms of childhood.

Childhood brain tumours in Cape Town.

Brain tumours are the commonest solid tumours of childhood; 145 patients under the age of 14 years with intracranial tumours treated between 1979 and 1985 are presented. Of the tumours 63% were situated in the posterior fossa while 37% were supratentorial. Medulloblastomas accounted for 25% of the entire series. Modern methods of treatment are outlined.

Herniation of cerebellar tonsils following supratentorial shunt placement.

Acquired Chiari 1 following ventriculoperitoneal shunting is an extremely unusual event. We report the case of an 8-year-old boy who presented with clinical and radiological signs of cerebellar tonsil herniation shortly after the placement of a cystoperitoneal shunt. Quantitative analysis of posterior fossa volumes (PFV) revealed that the patient had a smaller posterior fossa than age-matched normal controls. This abnormality, expressed as a decreased ratio between the posterior fossa and the supratentorial cavities (PFR), had already been present when the preoperative MRI was done. Our results suggest that preexisting structural abnormalities in the posterior fossa may constitute an important factor in the development tonsillar herniation following supratentorial shunts.