Search PubMed⌕ Search

Biomedical subjects

J A Lazareff

Publications and source records attributed to J A Lazareff.

At least 19 recordsLinked to original sources
PubMed2001

Functional assessment of children with cerebral palsy following limited (L4-S1) selective posterior rhizotomy--a preliminary report.

OBJECTIVE: Selective Posterior Rhizotomy (SPR) is effective for reducing spasticity in children with cerebral palsy (CP). Nonetheless, extensive sensory deafferentation associated with this procedure can lead to prolonged postoperative hypotonia that delays the functional recovery of the patient. As lumbar rhizotomy provokes suprasegmental hypotonia, we hypothesized that reducing the extent of the deafferentation to the roots of L4-S1 levels would reduce the risk of postoperative hypotonia. METHODS AND RESULTS: Five patients with spastic cerebral palsy (4 males and 1 females, age range: 4-12 years) underwent limited selective dorsal rhizotomy (LSDR) of three (L4-S1) dorsal roots. All patients were able to walk independently prior to surgery. Functional assessments of these patients were performed pre and post operatively. Assessments included spasticity evaluation, passive range of motion, and sagittal plane kinematics of the hip, knee, and ankle during walking. Following surgery, reduced spasticity, increased passive range of motion and improved joint motion during walking was observed. Specifically, peak hip and knee extension and peak ankle dorsiflexion increased while peak plantarflexion decreased. CONCLUSIONS: Strength and motor control were not adversely affected by this procedure in any of the subjects and all patients actually demonstrated improvements. Previous studies have demonstrated that LSDR is highly effective in reducing spasticity and achieving functional outcome in spastic children. The results of this study demonstrated improved function during walking as assessed using gait analysis techniques.

Ambulatory Care↗
PubMed2001

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.

Acute Disease↗
PubMed2000

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.

Adolescent↗
PubMed1999

Limited (L4-S1, L5-S1) selective dorsal rhizotomy for reducing spasticity in cerebral palsy.

Selective posterior rhizotomy is effective for relieving spasticity associated with cerebral palsy. In current techniques dorsal roots from L1/L2 to S1/S2 are selectively divided. With transoperative electromyography (EMG) significant sensory loss has been prevented, but postoperative hypotonia following excessive reduction of the fusimotor drive is still of concern for surgeons and therapists. To decrease the volume of deafferentiated rootlets we proposed a limited selective posterior rhizotomy (LPSR) that limits the extent of the surgery to three (L4-S1) or two (L5-S1) dorsal roots. We present the results of two group of spastic children; group 1 (n = 59, 32 quadriplegic and 27 diplegic) who had a L4-S1 LPSR, and group 2 (n = 12) in whom L5 and S1 were selectively rhizotomized. Posture, passive movilization, range of joint movement, and muscle tone in hip flexors, adductors, leg flexors and plantar flexors were graded according to the method proposed by Sindou and Jeanmonod. In all groups these was a significant reduction of the mentioned parameters (Friedman test p < 0.001) at 6, 12 and 18 months after surgery. The preoperative and postoperative ability to ambulate was classified into five grades. In all groups there was a significant (chi 2 between p < 0.01 and p < 0.001) improvement in the quality of their gait. A third of the patients achieved some form of independent ambulation. Our results suggest that extensive selective deafferentation of the lower limbs is not an absolute requisite for reducing muscle tone or achieving functional improvement in spastic children.

Cerebral Palsy↗
PubMed1999

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.

Adolescent↗
PubMed1999

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.

Astrocytoma↗
PubMed1999

Tumor volume and growth kinetics in hypothalamic-chiasmatic pediatric low grade gliomas.

Pediatric low grade gliomas evidence a tendency towards quiescent growth, thus complicating the clinical management of nonresected tumors whose clinical behavior may be difficult to predict. We decided to explore the hypothesis of possible correlation in pediatric low grade glioma between tumor volume and growth rate. We identified 6 children with hypothalamic chiasmatic lesions. Five of these patients were treated only with biopsy and 1 with repeated partial tumor resection. All of 6 patients had 10-15 sequential brain MRI over a time span of 3-8 years. Tumor volume was determined using Sigma Scan Image software. The results were analyzed utilizing two equations for modeling tumor growth: exponential and Gompertz. In 4 patients whose tumor volume was approximately 80-100 cm(3) at the time of diagnosis, slow spontaneous partial regression was observed. In the other patients deceleratory or exponential tumor growth was volume-dependent. Our results suggest that growth of pediatric low grade glioma decelerates as tumor becomes large and that the Gompertz model for tumor growth is useful for understanding the growth kinetics of pediatric low grade glioma.

Astrocytoma↗
PubMed1998

Multiple shunt failures: an analysis of relevant factors.

Ventricular shunts that require multiple revisions are familiar to pediatric neurosurgeons. We conducted a retrospective study to determine whether patients who require repeated shunt revisions represent a particular cohort within shunted hydrocephalic children. The clinical records of 244 children who had undergone shunt procedures between January 1990 and January 1996 were examined. They were divided into group 1: children with no shunt failure (n=136), group 2: children with one shunt revision (n=52), group 3: children with 2 or 3 shunt revisions (n=34), and group 4: patients who had 4 or more shunt revisions (n=22). Patients in groups 3 and 4 accounted for 54.8% of the total of 531 shunt procedures. Etiology of hydrocephalus, nature of the dysfunction, CSF characteristics, and variables related to the surgical procedure were analyzed for each group. We observed a progressive shortening of the intervals between revisions as the numbers of surgeries increased, indicating that shunts that tended to fail repeatedly did so sooner than those that did not. A Kaplan-Meier shunt survival curve showed that group 2 had a slower rate of failure than either group 3 (chi2=7.13, P<0.01) or group 4 (chi2=4.76, P<0.05). The etiologies of the hydrocephalus were not randomly distributed among the four groups (chi2=81.4, P<0.001); there was a predominance of congenital conditions in group 1. Repeated shunt revisions were associated with a progressive increase in the concentration of monocytes in the CSF (Kruskal-Wallis, P<0.05). Our data suggest that multiple shunt revisions constitute a phenomenon that may be caused by specific, still unidentified, biological factors.

Adolescent↗
PubMed1998

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.

Arnold-Chiari Malformation↗
PubMed1998

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.

Adolescent↗
PubMed1997

An enzyme immunoassay for neuron-specific enolase in cerebrospinal fluid.

A direct (as opposed to competitive) enzyme immunoassay (EIA) was developed to detect neuron-specific enolase (NSE) in cerebrospinal fluid (CSF). Most common methods of evaluating NSE levels have utilized radioimmunoassay. These are highly sensitive, but cannot be employed in laboratories not equipped or licensed for the use of radioisotopes. The EIA developed here shows sensitivity within the physiological range of values for CSF-NSE (> I ng/ml) and can be used in laboratories with appropriate densitometric scanning capabilities. The assay was applied to CSF samples obtained from patients with a variety of diagnoses at the time of surgical intervention for their respective disorders. While there were no diagnostically significant differences between the level of NSE in CSF from patients with different neurological disorders utilized in the development of this procedure, we were able to differentiate between marginally different levels of NSE. We conclude that we have developed a safe, fast, reliable, and sensitive assay for NSE in the CSF that can be used to study NSE levels in a variety of neurological cases.

Analysis of Variance↗
PubMed1996

Proton magnetic resonance spectroscopic imaging of pediatric low-grade astrocytomas.

Despite their uniform histologic appearance, pediatric low-grade astrocytomas (LGA) often exhibit a rather unpredictable clinical course. It is presently unclear whether certain specific genetic, immunologic and/or metabolic features underlie these observed variations. In order to address this question we examined the tumor distribution of choline compounds (Cho), creatine (Cr) and N-acetyl aspartate (NAA) in seven children with midline LGA by means of proton magnetic resonance spectroscopy imaging (H-MRSI). Studies were performed with a 1.5 T GE Signa Scanner equipped with the standard head coil; nominal voxel size was 7.5 x 7.5 x 15 mm. This spatial resolution allowed us to select and independently evaluate multiple regions of interest (ROI) in the tumor as well as in areas of normal brain from the same individual. Normalized values of the observed signal intensities demonstrated a lower NAA and Cr content in the tumors than in the surrounding normal brain. Intratumoral Cho signals were also below normal values in all but one patient. The average Cho:NAA ratio was consistently higher in the tumor than in the normal brain. However, there was a wide variation (up to fourfold) in the Cho:NAA ratios of different ROIs, even within the same tumor. Our results clearly indicate that pediatric LGAs are metabolically heterogeneous, a feature that may be relevant to the understanding of their variable biologic behavior. Inasmuch as unique metabolic patterns were observed in some LGAs, we believe that systematic HMRSI studies of these patients may help define subsets within the group with specific therapeutic requirements.

Astrocytoma↗
PubMed1996

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.

Adolescent↗
PubMed1995

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.

Aging↗
PubMed1995

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.

Brain↗
PubMed1993

[Lumbar dermal sinus as a cause of intramedullary and subdural abscess. Report of 2 cases].

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.

Abscess↗