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Maryam Fouladi, Richard Heideman, James W. Langston, Larry E. Kun, Stephen J. Thompson and Amar Gajjar

✓ This report and the accompanying review of the literature address the challenges, when using surveillance magnetic resonance (MR) imaging, of establishing the origin of newly detected central nervous system lesions. Routine surveillance MR imaging in a 16-year-old boy, whose medulloblastoma had been successfully treated, demonstrated asymptomatic nodular leptomeningeal enhancement of the brain and spinal cord, which was consistent with recurrent disease. Examination of the cerebrospinal fluid, however, led to the diagnosis of bacterial meningitis. Two weeks after completion of antibiotic therapy, the original MR imaging findings were seen to have resolved. This case illustrates the importance of considering clinical and laboratory data, including results from a complete examination of the cerebrospinal fluid, when interpreting the origin of new lesions revealed by MR imaging.

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Nicholas S. Phillips, Robert A. Sanford, Kathleen J. Helton, Frederick A. Boop, Ping Zou, Tanya Tekautz, Amar Gajjar and Robert J. Ogg

✓Brainstem gliomas are a heterogeneous group of lesions that account for 15% of all pediatric tumors of the central nervous system. Diagnosis and treatment planning for these tumors is based on the observation of Epstein and Farmer that the growth of lesions with low malignant potential is limited by the anatomical structures of the brainstem. Surgery is offered only to those patients with a high probability of harboring a low-grade tumor, because the attendant risk for significant morbidity outweighs the therapeutic benefit of debulking the tumor in cases of high-grade tumors.

The authors report two cases that highlight the potential of diffusion tensor (DT) imaging to identify local white matter tracts in the pons, medulla, and cervical cord and to improve the preoperative assessment of low-grade gliomas. Preoperative DT imaging in both cases demonstrated that the white matter tracts were displaced by the bulk of the low-grade tumors but were structurally preserved. Intraoperative and neurological findings were consistent with the preoperative interpretation of the DT images. These cases demonstrate that DT imaging is a useful method for visualizing the relationship between tumor and normal brainstem white matter architecture, as well as for improving the surgical evaluation and management of pediatric brainstem tumors.

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Mark Van Poppel, Paul Klimo Jr., Mariko Dewire, Robert A. Sanford, Frederick Boop, Alberto Broniscer, Karen Wright and Amar J. Gajjar

Object

Brain tumors in infants are often large, high grade, and vascular, making complete resection difficult and placing children at risk for neurological complications and excessive blood loss. Neoadjuvant chemotherapy may reduce tumor vascularity and volume, which can facilitate resection. The authors evaluated how an ongoing institutional prospective chemotherapy trial would affect patients who did not have a gross-total resection (GTR) immediately and who therefore required further surgical intervention to achieve definitive tumor resection.

Methods

Thirteen infants (4 girls and 9 boys) who were enrolled in an institutional protocol in which they were treated with multiagent chemotherapy (methotrexate, vincristine, cisplatin, and cyclophosphamide with vinblastine for high-risk patients) subsequently underwent second-look surgery. The primary outcome was extent of resection achieved in postchemotherapy surgery. Secondary outcomes included intraoperative blood loss, radiographic response to the chemotherapy, complications during chemotherapy, and survival.

Results

Three infants underwent biopsy, 9 underwent subtotal resection, and 1 patient did not undergo surgery prior to chemotherapy. On subsequent second-look surgery, 11 of 13 patients had a GTR, 1 had a near-total resection, and 1 had a subtotal resection. In each case, a marked reduction in tumor vascularity was observed intraoperatively. The average blood loss was 19% of estimated blood volume, and 6 (46%) of 13 patients required a blood transfusion. Radiographically, chemotherapy induced a reduction in tumor volume in 9 (69%) of 13 patients. Emergency surgery was required in 2 patients during chemotherapy, 1 for intratumoral hemorrhage and 1 for worsening peritumoral edema. The average follow-up period for this cohort was 16.5 months, and at last follow-up, 4 patients (31%) had died, 1 patient had progressive metastatic spinal disease, and the rest had either no evidence of disease or stable disease.

Conclusions

A GTR of pediatric brain tumors is one of the most important predictors of outcome. The application of the authors' neoadjuvant induction chemotherapy protocol in a variety of tumor types resulted in devascularization of all tumors and volume regression in the majority, and subsequently facilitated resection, with acceptable intraoperative blood loss. Intracranial complications may occur during chemotherapy, ranging from incidental and asymptomatic to life threatening, necessitating close monitoring of these children.

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Patricia L. Robertson, Karin M. Muraszko, Emiko J. Holmes, Richard Sposto, Roger J. Packer, Amar Gajjar, Mark S. Dias and Jeffrey C. Allen

Object

Cerebellar mutism syndrome (CMS) is a unique postoperative syndrome typically arising 1 to 2 days after resection of a midline posterior fossa tumor; it consists of diminished speech progressing to mutism, emotional lability, hypotonia, and ataxia. Most descriptions have been limited to small institutional series using a retrospective chart review methodology.

Methods

The authors incorporated a CMS questionnaire in two large clinical trials (Children’s Cancer Group [CCG] 9931, treatment for high-risk medulloblastoma/primitive neuroectodermal tumor; and CCG/Pediatric Oncology Group [POG] A9961, treatment for average-risk medulloblastoma) to prospectively survey for incidence, severity, and possible causes of CMS in children with newly diagnosed medulloblastoma. Information pertaining to 450 of the 463 patients enrolled in the studies was available for review (82 patients in CCG 9931, and 368 patients in CCG/POG A9961).

Cerebellar mutism syndrome occurred in 107 (24%) of 450 children. Symptom intensity was judged to have been severe in 43%, moderate in 49%, and mild in 8% of these 107 patients. Mutism and ataxia were the features most frequently judged as severe. In both cohorts, preoperative brainstem invasion was the only feature that correlated with risk of CMS. One year after diagnosis, nonmotor speech/language deficits, neurocognitive deficits, and/or ataxia persisted in a significant fraction of patients.

Conclusions

Nearly one quarter of patients who underwent resection of a medulloblastoma developed symptoms of CMS, of which 92% were judged to be of moderate or severe intensity. Brainstem invasion by tumor was the only risk factor that correlated positively with CMS occurrence; there was a negative correlation with cerebellar hemisphere tumor location. As more radical resections are attempted for medulloblastoma, the potential for increased morbidity must be carefully weighed against prognostic factors, especially in patients with brainstem invasion.

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Amar Gajjar, Ravi Bhargava, Jesse J. Jenkins, Richard Heideman, Robert A. Sanford, James W. Langston, Andrew W. Walter, John F. Kuttesch, Michael Muhlbauer and Larry E. Kun

✓ Little is known about low-grade astrocytoma with neuraxis dissemination at diagnosis. A review of medical records identified this phenomenon in eight of 150 pediatric patients evaluated between 1985 and 1994 for histologically confirmed low-grade astrocytoma. These patients (five male and three female) ranged in age from 5 months to 20 years (median 8 years). Symptoms of neuraxis disease were minimal or absent. Primary tumor sites were the hypothalamus in four cases, brainstem/spinal cord in three, and temporal lobe in one. Patterns of dissemination (evaluated by computerized tomography and/or magnetic resonance imaging techniques) appeared to be related to the primary site: hypothalamic tumors metastasized along the ventricular cerebrospinal fluid pathways, and tumors in other locations disseminated along subarachnoid pathways. Following initial treatment with chemotherapy (in three), partial resection (in one), radiation therapy (in three), and chemotherapy plus irradiation (in one), four patients required salvage therapy for progressive or recurrent disease. Seven of the eight patients are alive with stable or progressive disease 6 to 105 months postdiagnosis (median 15 months). Low-grade astrocytoma with initial neuraxis dissemination is responsive to chemotherapy and radiation, a proportion showing periods of stable disease. The optimum therapy or combination of therapies remains unclear.

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Paul Klimo Jr., Atmaram S. Pai Panandiker, Clinton J. Thompson, Frederick A. Boop, Ibrahim Qaddoumi, Amar Gajjar, Gregory T. Armstrong, David W. Ellison, Larry E. Kun, Robert J. Ogg and Robert A. Sanford

Object

Whereas diffuse intrinsic pontine gliomas generally have a short symptom duration and more cranial nerve involvement, focal brainstem gliomas are commonly low grade, with fewer cranial neuropathies. Although these phenotypic distinctions are not absolute predictors of outcome, they do demonstrate correlation in most cases. Because there is a limited literature on focal brainstem gliomas in pediatric patients, the objective of this paper was to report the management and outcome of these tumors.

Methods

The authors reviewed the records of all children diagnosed with radiographically confirmed low-grade focal brainstem gliomas from 1986 to 2010. Each patient underwent biopsy or resection for tissue diagnosis. Event-free survival (EFS) and overall survival were evaluated. Univariate analysis was conducted to identify demographic and treatment variables that may affect EFS.

Results

Fifty-two patients (20 girls, 32 boys) with follow-up data were identified. Median follow-up was 10.0 years, and the median age at diagnosis was 6.5 years (range 1–17 years). The tumor locations were midbrain (n = 22, 42%), pons (n = 15, 29%), and medulla (n = 15, 29%). Surgical extirpation was the primary treatment in 25 patients (48%). The 5- and 10-year EFS and overall survival were 59%/98% and 52%/90%, respectively. An event or treatment failure occurred in 24 patients (46%), including 5 deaths. Median time to treatment failure was 3.4 years. Disease progression in the other 19 patients transpired within 25.1 months of diagnosis. Thirteen of these patients received radiation, including 11 within 2 months of primary treatment failure. Although children with intrinsic tumors had slightly better EFS at 5 years compared with those with exophytic tumors (p = 0.054), this difference was not significant at 10 years (p = 0.147). No other variables were predictive of EFS.

Conclusions

Surgery suffices in many children with low-grade focal brainstem gliomas. Radiation treatment is often reserved for disease progression but offers comparable disease control following biopsy. In the authors' experience, combining an assessment of clinical course, imaging, and tumor biopsy yields a reasonable model for managing children with focal brainstem tumors.

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David S. Hersh, Rahul Kumar, Kenneth A. Moore, Luke G. F. Smith, Christopher L. Tinkle, Jason Chiang, Zoltan Patay, Amar Gajjar, Asim F. Choudhri, Jorge A. Lee-Diaz, Brandy Vaughn and Paul Klimo Jr.

OBJECTIVE

Biopsies of brainstem lesions are performed to establish a diagnosis in the setting of an atypical clinical or radiological presentation, or to facilitate molecular studies. A better understanding of the safety and diagnostic yield of brainstem biopsies would help guide appropriate patient selection.

METHODS

All patients who underwent biopsy of a brainstem lesion during the period from January 2011 to June 2019 were reviewed. Demographic, radiological, surgical, and outcome data were collected.

RESULTS

A total of 58 patients underwent 65 brainstem biopsies during the study period. Overall, the median age was 7.6 years (IQR 3.9–14.2 years). Twenty-two of the 65 biopsies (34%) were open, 42 (65%) were stereotactic, and 1 was endoscopic. In 3 cases (5%), a ventriculoperitoneal shunt was placed, and in 9 cases (14%), a posterior fossa decompression was performed during the same operative session as the biopsy. An intraoperative MRI (iMRI) was performed in 28 cases (43%). In 3 of these cases (11%), the biopsy was off target and additional samples were obtained during the same procedure. New neurological deficits were noted in 5 cases (8%), including sensory deficits, ophthalmoparesis/nystagmus, facial weakness, and hearing loss; these deficits persisted in 2 cases and were transient in 3 cases. A pseudomeningocele occurred in 1 patient; no patients developed a CSF leak or infection. In 8 cases (13%) an additional procedure was needed to obtain a diagnosis.

CONCLUSIONS

Brainstem biopsies are safe and effective. Target selection and approach should be a collaborative effort. iMRI can be used to assess biopsy accuracy in real time, thereby allowing any adjustment if necessary.

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Kathleen J. Helton, James K. Weeks, Nicholas S. Phillips, Ping Zou, Larry E. Kun, Raja B. Khan, Amar Gajjar, Maryam Fouladi, Alberto Broniscer, Frederick Boop, Chin-Shang Li and Robert J. Ogg

Object

Diffusion tensor (DT) imaging has been used to predict postoperative motor function in patients with supratentorial tumors. The authors sought to determine whether DT imaging and white matter tractography could detect axonal degeneration in patients with brainstem tumors.

Methods

A cross-sectional, retrospective study of 7 patients with brainstem tumors and 8 healthy volunteers was performed. The DT imaging data were normalized and regions of interest (ROIs) with the highest probability of sensory and motor connections were selected using the Talairach Atlas to identify the 3D millimetric coordinates of white matter tracts. An iterative process involving fractional anisotropy (FA), apparent diffusion coefficients (ADCs), and color maps was developed to precisely select ROIs in the bilateral sensory and motor tracts. The FA and ADC values were calculated for each ROI.

Results

The FA values of sensory and motor tracts significantly differed between the patient and healthy volunteer groups (p < 0.05), whereas no significant changes were found in the splenium or genu of the corpus callosum. The FA values were altered proximal and distal to the brainstem tumors with a bimodal peak of antegrade decreased FA involving second- and third-order sensory axons and retrograde decreased FA of motor axons.

Conclusions

This study demonstrates changes in diffusion properties of sensory and motor tracts consistent with degeneration to further characterize brainstem tumors in children, and the results warrant the planning of prospective trials. The rigorous methods the authors describe may provide valuable information when planning biopsies or debulking of unusual brainstem tumors, as well as improve prognostication of the possible functional tract recovery following therapy.