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Kyle D. Weaver and Matthew G. Ewend

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Kyle D. Weaver, Diane Armao, Joseph M. Wiley and Matthew G. Ewend

✓ This 10-year-old girl presented with a 1-month history of progressive bulbar palsy and a solitary enhancing mass originating within the floor of the fourth ventricle. Results of initial imaging studies and presentation were suggestive of neoplasia. Subtotal resection was performed and pathological examination revealed the mass to be a histiocytic lesion, with no evidence of a glioma. The patient had no other stigmata of histiocytosis and was treated with steroid medications, resulting in prolonged resolution of the lesion. This case demonstrates that for discrete brainstem lesions the differential diagnosis includes entities other than glioma for which treatment is available. Biopsy sampling should be considered when technically feasible.

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Jonathan A. Forbes, Matthew L. Carlson, Saniya S. Godil, Marc L. Bennett, George B. Wanna and Kyle D. Weaver

In this publication, video format is utilized to review the operative technique of retrosigmoid craniotomy for resection of acoustic neuroma with attempted hearing preservation. Steps of the operative procedure are reviewed and salient principles and technical nuances useful in minimizing complications and maximizing efficacy are discussed.

The video can be found here: http://youtu.be/PBE5rQ7B0Ls.

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Kaleb Yohay, Betty Tyler, Kyle D. Weaver, Andrea C. Pardo, Dan Gincel, Jaishri Blakeley, Henry Brem and Jeffrey D. Rothstein

Object

The poor outcome of malignant gliomas is largely due to local invasiveness. Previous studies suggest that gliomas secrete excess glutamate and destroy surrounding normal peritumoral brain by means of excitotoxic mechanisms. In this study the authors assessed the effect on survival of 2 glutamate modulators (riluzole and memantine) in rodent glioma models.

Methods

In an in vitro growth inhibition assay, F98 and 9L cells were exposed to riluzole and memantine. Mouse cerebellar organotypic cultures were implanted with F98 glioma cells and treated with radiation, radiation + riluzole, or vehicle and assessed for tumor growth. Safety and tolerability of intracranially implanted riluzole and memantine CPP:SA polymers were tested in F344 rats. The efficacy of these drugs was tested against the 9L model and riluzole was further tested with and without radiation therapy (RT).

Results

In vitro assays showed effective growth inhibition of both drugs on F98 and 9L cell lines. F98 organotypic cultures showed reduced growth of tumors treated with radiation and riluzole in comparison with untreated cultures or cultures treated with radiation or riluzole alone. Three separate efficacy experiments all showed that localized delivery of riluzole or memantine is efficacious against the 9L gliosarcoma tumor in vivo. Systemic riluzole monotherapy was ineffective; however, riluzole given with RT resulted in improved survival.

Conclusions

Riluzole and memantine can be safely and effectively delivered intracranially via polymer in rat glioma models. Both drugs demonstrate efficacy against the 9L gliosarcoma and F98 glioma in vitro and in vivo. Although systemic riluzole proved ineffective in increasing survival, riluzole acted synergistically with radiation and increased survival compared with RT or riluzole alone.

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Matthew L. Carlson, William R. Copeland III, Colin L. Driscoll, Michael J. Link, David S. Haynes, Reid C. Thompson, Kyle D. Weaver and George B. Wanna

Object

The goals of this study were to report the clinical presentation, radiographic findings, operative strategy, and outcomes among patients with temporal bone encephaloceles and cerebrospinal fluid fistulas (CSFFs) and to identify clinical variables associated with surgical outcome.

Methods

A retrospective case series including all patients who underwent a middle fossa craniotomy or combined mastoid–middle cranial fossa repair of encephalocele and/or CSFF between 2000 and 2012 was accrued from 2 tertiary academic referral centers.

Results

Eighty-nine consecutive surgeries (86 patients, 59.3% women) were included. The mean age at time of surgery was 52.3 years, and the left side was affected in 53.9% of cases. The mean delay between symptom onset and diagnosis was 35.4 months, and the most common presenting symptoms were hearing loss (92.1%) and persistent ipsilateral otorrhea (73.0%). Few reported a history of intracranial infection (6.7%) or seizures (2.2%).

Thirteen (14.6%) of 89 cases had a history of major head trauma, 23 (25.8%) were associated with chronic ear disease without prior operation, 17 (19.1%) occurred following tympanomastoidectomy, and 1 (1.1%) developed in a patient with a cerebral aqueduct cyst resulting in obstructive hydrocephalus. The remaining 35 cases (39.3%) were considered spontaneous. Among all patients, the mean body mass index (BMI) was 35.3 kg/m2, and 46.4% exhibited empty sella syndrome. Patients with spontaneous lesions were statistically significantly older (p = 0.007) and were more commonly female (p = 0.048) compared with those with nonspontaneous pathology. Additionally, those with spontaneous lesions had a greater BMI than those with nonspontaneous disease (p = 0.102), although this difference did not achieve statistical significance.

Thirty-two surgeries (36.0%) involved a middle fossa craniotomy alone, whereas 57 (64.0%) involved a combined mastoid–middle fossa repair. There were 7 recurrences (7.9%); 2 patients with recurrence developed meningitis. The use of artificial titanium mesh was statistically associated with the development of recurrent CSFF (p = 0.004), postoperative wound infection (p = 0.039), and meningitis (p = 0.014). Also notable, 6 of the 7 cases with recurrence had evidence of intracranial hypertension. When the 11 cases that involved using titanium mesh were excluded, 96.2% of patients whose lesions were reconstructed with an autologous multilayer repair had neither recurrent CSFF nor meningitis at the last follow-up.

Conclusions

Patients with temporal bone encephalocele and CSFF commonly present with persistent otorrhea and conductive hearing loss mimicking chronic middle ear disease, which likely contributes to a delay in diagnosis. There is a high prevalence of obesity among this patient population, which may play a role in the pathogenesis of primary and recurrent disease. A middle fossa craniotomy or a combined mastoid–middle fossa approach incorporating a multilayer autologous tissue technique is a safe and reliable method of repair that may be particularly useful for large or multifocal defects. Defect reconstruction using artificial titanium mesh should generally be avoided given increased risks of recurrence and postoperative meningitis.