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Kris A. Smith and Harold L. Rekate

✓ Tethering of the spinal cord in the lumbar and sacral regions of children with congenital anomalies is a well-recognized problem; however, tethering in the cervical region has rarely been reported. A search of the literature revealed no reports of symptomatic postoperative cervical spinal cord tethering. The authors present five cases of delayed postoperative cervical spinal cord tethering and discuss the benefit of detethering in these patients. All five patients were young (16 to 42 years of age) at presentation. All had done well after an initial surgical procedure but returned between 1 and 31 years postoperatively with symptoms including severe headache, upper-extremity pain, and progressive neurological deficits. In each case, magnetic resonance imaging indicated dorsal tethering of the cord in the cervical region. Surgical exploration with microscopic sharp detethering of the cervical cord was performed on each patient with favorable results. To avoid retethering, wide Tutoplast duraplasty is recommended.

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Kris A. Smith and Robert F. Spetzler

✓ The use of the supratentorial—infraoccipital approach is reported in seven patients with posteromedial temporal lobe lesions. No patient had permanent morbidity. Gross total resection of three low-grade gliomas and two gangliogliomas was achieved in five patients; one patient had subtotal resection of a low-grade glioma with adjacent gliosis, and one was initially thought to have a glioma but proved to have encephalomalacia on final pathological analysis. The patients ranged in age from 5 to 34 years. All seven patients presented with seizures, and four had uncontrolled seizures preoperatively. Six have been seizure-free since surgery (mean follow-up period 15 months), and one is well controlled on anticonvulsant medication. An anatomical study was performed to delineate the microsurgical anatomy relevant to operating on the medial temporal lobe through this posterior approach. A viewing wand intraoperative navigational system was utilized with this approach and proved helpful in gaining access as far anterior as the uncus through this occipital craniotomy. This approach is favorable in selected patients with posterior, medial, temporal lobe tumors because resection of otherwise difficult lesions may be accomplished without sacrificing lateral temporal lobe cortex or transecting the optic radiations.

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Erratum

Prospective trial of gross-total resection with Gliadel wafers followed by early postoperative Gamma Knife radiosurgery and conformal fractionated radiotherapy as the initial treatment for patients with radiographically suspected, newly diagnosed glioblastoma multiforme

L. Fernando Gonzalez and Kris A. Smith

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Kris A. Smith, Gary E. Kraus, Blake A. Johnson and Robert F. Spetzler

✓ The case of a giant posterior communicating artery (PCoA) aneurysm is reported in which the initial presentation was coma secondary to obstructive hydrocephalus. The primary radiological diagnosis was a probable craniopharyngioma. A cerebral angiogram revealed a partially thrombosed giant PCoA aneurysm on the right side. The patient underwent pterional craniotomy with aneurysm clipping and thrombectomy to relieve mass effect, and has made a good recovery. Review of the literature documents that giant PCoA aneurysms are rare. This is believed to be the first reported case of a PCoA aneurysm presenting as a third ventricle mass with obstructive hydrocephalus. The magnetic resonance imaging characteristics of those third ventricle masses that mandate vascular workup are discussed.

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Ryan Smith, Kris A. Smith, Christopher A. Biggs and Adrienne C. Scheck

Object

The goal of this study was to develop an assay that makes possible the assessment of the glioma cell response to single-fraction high-dose Gamma Knife surgery. In this assay, the isolation of radioresistant cell subpopulations facilitates mechanistic studies of radioresistance.

Methods

A tissue-equivalent paraffin phantom with an aperture capable of holding an Opticell cell culture cassette was developed for treatment with the Leksell Gamma Knife model C. A second apparatus, which the authors also created, uses the manufacturer-supplied polystyrene phantom, thereby allowing this assay to be performed in the Leksell Gamma Knife Perfexion. After treatment, the cells were morphologically assessed to determine their response to radiation treatment. Two specific parameters were used to determine radiosensitivity: 1) the diameter of the clearing zone, defined as the central region of cell death; and 2) the number of surviving colonies within this central high-dose clearing zone.

Results

Radioresistance was compared in 2 different cell lines from glioblastomas. The first cell line, ME, was established from a primary tumor before its treatment, and the second cell line, DIV, was established from a tumor that recurred after treatment with chemotherapy and fractionated radiotherapy. The ME cell line had the most robust response to radiosurgery, as characterized by a consistently larger clearing zone (28.33 ± 1.1 mm). In contrast, the clearing zone produced when the DIV cell line was used was 24.0 ± 1 mm, indicating an approximate response difference of 5 Gy. The mean number of surviving colonies within the clearing zone for the ME cell line was 1.33 ± 1 compared with that for the DIV cell line, which was 66.67 ± 2.

Conclusions

The authors developed a biological dosimeter to model the response of cells from glioblastomas to single-fraction high-dose radiation. This system also allows the identification and isolation of radioresistant cells.

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M. Yashar S. Kalani, Sudarshan Iyer, Stephen W. Coons and Kris A. Smith

Intradural spinal teratomas are rare tumors of the spinal cord that are infrequently encountered in children. Although the mechanistic basis for the formation of these tumors is unclear, several lines of evidence suggest that a dysembryogenic process in the embryo results in their formation. The authors present a case of spinal intradural teratoma in an 18-year-old, previously healthy man and review the literature linking the development of these tumors to defects in neurulation and embryogenesis.

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C. Leland Rogers, Andrew G. Shetter, Francisco A. Ponce, Jeffrey A. Fiedler, Kris A. Smith and Burton L. Speiser

Object. The authors assessed the efficacy and complications from gamma knife radiosurgery (GKS) for multiple sclerosis (MS)-associated trigeminal neuralgia (TN).

Methods. There were 15 patients with MS-associated TN (MS—TN). Treatment involved three sequential protocols, 70 to 90-Gy maximum dose, using a single 4-mm isocenter targeting the ipsilateral trigeminal nerve at its junction with the pons with the 50% isodose. Pain was appraised by each patient by using Barrow Neurological Institute (BNI) Scores I through IV: I, no pain; II, occasional pain not requiring medication; IIIa, no pain but continued medication; IIIb, some pain, controlled with medication; IV, some pain, not controlled with medication; and V, severe pain/no pain relief.

With a mean follow up of 17 months (range 6–38 months), 12 (80%) of 15 patients experienced pain relief. Three patients (20%) reported no relief (BNI Score V). For responders, the mean latency from treatment to the onset of pain relief was 13 days (range 1–61 days). Maximal relief was achieved after a mean latency of 56 days (range 1–157 days). Five patients underwent a second GKS after a mean interval of 534 days (range 231–946 days). The mean maximum dose at this second treatment was 48 Gy. The target was unchanged from the first treatment. All five patients who underwent repeated GKS improved. Complications were limited to delayed facial hypesthesias. Two (13%) of 15 patients experienced onset of numbness after the first GKS, as well as two of five patients following a second GKS. The patients found this mild and not bothersome. Each patient who developed hypesthesias also experienced complete pain relief.

Conclusions. Gamma knife radiosurgery is an effective treatment for MS—TN. Radiosurgery carries an acceptable small risk of mild facial hypesthesias, and hypesthesia appears predictive of a favorable outcome.

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Colin J. Przybylowski, Tyler S. Cole, Jacob F. Baranoski, Andrew S. Little, Kris A. Smith and Andrew G. Shetter

OBJECTIVE

The objective of this study was to assess long-term outcomes of facial pain and numbness after radiosurgery for multiple sclerosis (MS)–related trigeminal neuralgia (MS-TN).

METHODS

The authors conducted a retrospective review of their Gamma Knife radiosurgeries (GKRSs) to identify all patients treated for MS-TN (1998–2014) with at least 3 years of follow-up. Treatment and clinical data were obtained via chart review and mailed or telephone surveys. Pain control was defined as a facial pain score of I–IIIb on the Barrow Neurological Institute (BNI) Facial Pain Intensity Scale. Kaplan-Meier analysis was performed to determine the rates of pain control after index and first salvage GKRS procedures. Patients could have had more than 1 salvage procedure. Pain control rates were based on the number of patients at risk during follow-up.

RESULTS

Of the 50 living patients who underwent GKRS, 42 responded to surveys (31 women [74%], median age 59 years, range 32–76 years). During the initial GKRS, the trigeminal nerve root entry zone was targeted with a single isocenter, using a 4-mm collimator with the 90% isodose line completely covering the trigeminal nerve and the 50% isodose line abutting the surface of the brainstem. The median maximum radiation dose was 85 Gy (range 50–85 Gy). The median follow-up period was 78 months (range 36–226 months). The rate of pain control after the index GKRS (n = 42) was 62%, 29%, 22%, and 13% at 1, 3, 5, and 7 years, respectively. Twenty-eight patients (67%) underwent salvage treatment, including 25 (60%) whose first salvage treatment was GKRS. The rate of pain control after the first salvage GKRS (n = 25) was 84%, 50%, 44%, and 17% at 1, 3, 5, and 7 years, respectively. The rate of pain control after the index GKRS with or without 1 salvage GKRS (n = 33) was 92%, 72%, 52%, 46%, and 17% at 1, 3, 5, 7, and 10 years, respectively. At last follow-up, 9 (21%) of the 42 patients had BNI grade I facial pain, 35 (83%) had achieved pain control, and 4 (10%) had BNI grade IV facial numbness (very bothersome in daily life).

CONCLUSIONS

Index GKRS offers good short-term pain control for MS-TN, but long-term pain control is uncommon. If the index GKRS fails, salvage GKRS appears to offer beneficial pain control with low rates of bothersome facial numbness.

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Alexander C. Whiting, Tsinsue Chen, Kyle I. Swanson, Corey T. Walker, Jakub Godzik, Joshua S. Catapano and Kris A. Smith

OBJECTIVE

Debate continues over proper surgical treatment for mesial temporal lobe epilepsy (MTLE). Few large comprehensive studies exist that have examined outcomes for the subtemporal selective amygdalohippocampectomy (sSAH) approach. This study describes a minimally invasive technique for sSAH and examines seizure and neuropsychological outcomes in a large series of patients who underwent sSAH for MTLE.

METHODS

Data for 152 patients (94 women, 61.8%; 58 men, 38.2%) who underwent sSAH performed by a single surgeon were retrospectively reviewed. The sSAH technique involves a small, minimally invasive opening and preserves the anterolateral temporal lobe and the temporal stem.

RESULTS

All patients in the study had at least 1 year of follow-up (mean [SD] 4.52 [2.57] years), of whom 57.9% (88/152) had Engel class I seizure outcomes. Of the patients with at least 2 years of follow-up (mean [SD] 5.2 [2.36] years), 56.5% (70/124) had Engel class I seizure outcomes. Preoperative and postoperative neuropsychological test results indicated no significant change in intelligence, verbal comprehension, perceptual reasoning, attention and processing, cognitive flexibility, visuospatial memory, or mood. There was a significant change in word retrieval regardless of the side of surgery and a significant change in verbal memory in patients who underwent dominant-side resection (p < 0.05). Complication rates were low, with a 1.3% (2/152) permanent morbidity rate and 0.0% mortality rate.

CONCLUSIONS

This study reports a large series of patients who have undergone sSAH, with a comprehensive presentation of a minimally invasive technique. The sSAH approach described in this study appears to be a safe, effective, minimally invasive technique for the treatment of MTLE.