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Hwa-Shain Yeh, Thomas A. Tomsick and John M. Tew Jr.

✓ Three cases of ruptured aneurysm of the distal posterior inferior cerebellar artery (PICA) presenting with isolated intraventricular hematoma are reported. All of the aneurysms originated from the lateral medullary segment of the PICA and ruptured into the lateral recess of the fourth ventricle. The diagnosis of distal PICA aneurysm should be considered if isolated intraventricular hematoma is found without obvious parenchymal hemorrhage or subarachnoid blood in the basal cisterns. Complete vertebral arteriography is a requisite for the recognition of this condition. The outcome in patients with these aneurysms should be good if surgical repair is performed before rebleeding occurs.

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Hwa-Shain Yeh, Shiro Kashiwagi, John M. Tew Jr. and Thomas S. Berger

✓ Between 1982 and 1986, 27 patients with seizure disorders due to cerebral arteriovenous malformation (AVM) were surgically treated by the authors. These patients had no history or clinical manifestation of intracranial hemorrhage. All were treated with anticonvulsant agents by their neurologists but became disabled due to inadequate control of seizures by medication, side effects of the anticonvulsant drugs, or the effects on their professional lives of even infrequent seizures. The age of the patients ranged from 13 to 61 years. There were 13 males and 14 females. The AVM's were smaller than 2 cm in four patients, between 2 and 4 cm in five, and larger than 4 cm in 18. The most frequent location of the AVM's was in the temporal lobe, followed by the frontal, parietal, and occipital lobes. All patients had preoperative electroencephalography (EEG) and intraoperative electrocorticography. Intraoperative recording of the amygdala and the hippocampus by depth electrodes was performed if the AVM's were located in the temporal lobe. Superficial or posterior temporal lobe AVM's often have remote seizure foci that involve the amygdala and hippocampus. All patients underwent craniotomy and total excision of their AVM's. Surgery was carried out under local anesthesia to allow localization by electrical stimulation if the AVM involved the speech area or the sensorimotor cortex. Based on the EEG findings, excision of the epileptogenic lesion in addition to the AVM was performed in 18 patients. In seven patients with AVM's located in the temporal lobe, remote seizure foci were identified and excised. The remote epileptic activity was particularly prominent in AVM's in the temporal lobe and usually involved mesial temporal structures.

Microscopic study of excised seizure foci showed gliosis in 26 cases, hemosiderin deposits in 10, and focal hemorrhage in four. There were no operative deaths. Two patients developed a hemiparesis and three suffered temporary dysphasia after surgery. Two patients had visual field deficits. The results of postoperative seizure control during the average follow-up period of 3 years 11 months were excellent in 21 patients, good in three, fair in two, and poor in one. The latter patient, whose epileptic lesion was not completely excised because of its location in the motor cortex, had poor seizure control postoperatively. Another patient required a second operation to remove a remote seizure focus.

In this series, proposed mechanisms of seizure associated with cerebral AVM include focal cerebral ischemia secondary to arteriovenous shunting, gliosis of the surrounding brain, and a secondary epileptogenesis in the temporal lobe. Successful seizure control can be obtained with wide excision of the epileptogenic foci surrounding the AVM's. In some circumstances, seizure foci remote from the vascular malformation must be excised.

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David John Yeh, Richard B. Hessler and Mark R. Lee

Primary leiomyosarcoma of the central nervous system is rare and has been described both de novo and following temporally remote radiotherapy for a different unrelated malignancy. The authors report the case of a 42-year-old man in whom 60Co radiation treatment had been performed for an unknown primary mass in the brainstem 25 years previously. He presented with progressive neurological deterioration after undergoing many years of conservative therapy. A stereotactic biopsy sampling procedure was performed, and examination of the left cerebral pedunculopontine lesion revealed a spindle cell neoplasm. Histopathological and immunohistochemical examination of the tumor obtained from definitive resection suggested leiomyosarcomatous transformation of ganglioglioma.

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Hwa-shain Yeh, John M. Tew Jr. and Maureen Gartner

✓ Prediction of seizure control after surgery on cerebral arteriovenous malformations (AVM's) is currently unavailable. Between 1982 and 1990, 54 patients (30 males, 24 females) with epilepsy caused by a supratentorial cerebral AVM, without prior manifestation of intracranial hemorrhage, were surgically treated. Patients ranged in age from 11 to 59 years at seizure onset and from 13 to 70 years at surgery; the duration of seizure history ranged from several months to 27 years. The AVM's were located in the temporal (17 cases), frontal (15), parietal (10), rolandic (two), and occipital (two) regions; eight were multilobular. All patients underwent preoperative electroencephalography, intraoperative electrocorticography, and total excision of the AVM; additional cortical excision was performed in 25 cases. Remote seizure foci were identified in the ipsilateral mesial temporal structure in 10 patients with AVM's located in the lateral or posterior temporal lobe and in one with an AVM in the anterior frontal region. Two patients required a second operation to remove a remote seizure focus. Among the 54 patients, there were no operative deaths. After surgical treatment, two patients developed hemiparesis, one had contralateral paresthesia of limbs, two suffered partial visual field defects, and five experienced temporary speech disturbances.

Postoperative results of seizure control during follow-up study (mean duration 4.8 years) were excellent in 38 patients (70.4%), good in 10 (18.5%), fair in five (9.3%), and poor in one (1.9%). Results appear to correlate with age at seizure onset, duration of seizures, location of lesions, and cortical excision. Excellent results were shown in 18 (60%) of 30 patients whose age at seizure onset was 30 years or less and in 20 (83.3%) of 24 whose age at seizure onset was greater than 30 years. Eighteen (90%) of 20 patients had excellent results when seizure duration was 1 year or less; only 25% of these underwent cortical excision. Twelve (71%) of the 17 temporal AVM's were associated with demonstrable epileptic foci. Secondary epileptogenesis can occur in humans with supratentorial cerebral AVM's; cortical excision in selected patients can improve the outcome of seizure control. Early surgery of a cerebral AVM in young patients presenting with epilepsy is an important consideration.

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Hwa-shain Yeh, Jeffrey T. Keller, Kim A. Brackett, Edmund Frank and John M. Tew Jr.

✓ As microvascular surgery has developed, the necessity for smaller arterial prostheses of less than 2 mm in internal diameter (ID) has increased markedly. Glutaraldehyde-stabilized human umbilical arteries with 1.5 to 2.0 mm ID are smaller than any other graft material currently available. This study was designed to determine whether this graft material has potential clinical application for microanastomosis.

Twenty male albino rats, each weighing 400 to 500 gm, were used in this study. The abdominal aorta was exposed and a 3- to 4-mm segment was resected. A 10-mm interposition graft of glutaraldehyde-stabilized human umbilical artery was implanted by end-to-end anastomosis. The patency of the grafts was determined by repeated operative exploration at intervals of 1 week, and 1, 3, 9, and 12 months. Two grafts were found to be occluded each time at the 1-, 3-, and 9-month explorations. At each exploration time, five rats were sacrificed and histopathological studies conducted. All five remaining grafts were patent at 12 months.

There was no evidence of endothelial proliferation on the luminal surface of the patent grafts as determined by scanning electron microscopy. The luminal surface and underlying region consisted of an amorphous proteinaceous-like material. Significant degeneration of the vessel wall was noted in all grafts surviving over 9 months. Central necrosis surrounded by a chronic inflammatory process that extended to and included the adventitia was observed in the occluded grafts. While the patency demonstrated was good, the tissue changes noted in the walls of the grafts indicate that further study is necessary before this material can be used as a graft in humans.

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Surgical resection of third ventricle colloid cysts

Preliminary results comparing transcallosal microsurgery with endoscopy

Adam I. Lewis, Kerry R. Crone, Jamal Taha, Harry R. van Loveren, Hwa-Shain Yeh and John M. Tew Jr.

✓ It is still not determined which is the best surgical option for third ventricle colloid cysts. Since 1990, the authors have used a steerable fiberscope to remove colloid cysts in seven patients and have performed microsurgery via a transcallosal approach in eight patients. The two techniques were compared for operating time, length of hospital stay, incidence of complications, recurrence, and hydrocephalus, and days spent recuperating before return to work to determine if endoscopic removal of colloid cysts is a safe and effective alternative to microsurgery. Statistical analysis was adjusted for age, sex, and presenting symptoms.

Microsurgical cases averaged 206 minutes of operating time whereas endoscopic cases averaged 127 minutes (p = 0.01). For combined days spent in the intensive care unit and on the ward, the patients averaged 9.5 days after microsurgery and 4 days after endoscopy (p = 0.05). Postoperative complications occurred in five of eight patients after microsurgery and in one of seven patients after endoscopy (p = 0.09); complications were transient and primarily related to short-term memory loss. In all patients, preoperative symptoms resolved and the cysts have not recurred. Postoperatively, one patient required a ventriculoperitoneal shunt after microsurgery but all patients were shunt-independent after endoscopy. Patients returned to work an average of 59 days after discharge following microsurgery compared with an average of 26 days after endoscopy (p = 0.05). Compared with transcallosal microsurgery for the removal of colloid cysts, these preliminary results show that a steerable endoscope reduced operating time and that patients spent fewer days in the hospital and returned to work sooner after endoscopy.

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Yoko T. Udaka, Lanipua A. Yeh-Nayre, Chiazo S. Amene, Scott R. VandenBerg, Michael L. Levy and John R. Crawford

Object

Pediatric low-grade glioma (LGG) is the most common brain tumor of childhood. Except for the known association of gross-total resection and improved survival rates, relatively little is known about the clinical and radiographic predictors of recurrent disease and the optimal frequency of surveillance MRI. The authors sought to determine the clinical and radiographic features associated with recurrent or progressive disease in a single-institutional series of children diagnosed with primary CNS LGG.

Methods

The authors performed a retrospective analysis of data obtained in 102 consecutive patients diagnosed at Rady Children's Hospital–San Diego between 1994 and 2010 with a biopsy-proven LGG exclusive of a diagnosis of neurofibromatosis. Tumor location, patient age, sex, and symptomatology were correlated with tumor progression or recurrence. Magnetic resonance imaging characteristics and neuroimaging surveillance frequency were analyzed in those children with progressive or recurrent disease.

Results

Forty-six of 102 children diagnosed with an LGG had evidence of recurrent or progressive disease between 2 months and 11 years (mean 27.3 months) after diagnosis. In the larger group of 102 children, gross-total resection was associated with improved progression-free survival (p = 0.012). The location of tumor (p = 0.26), age at diagnosis (p = 0.69), duration of symptoms (p = 0.72), histological subtype (p = 0.74), sex (p = 0.53), or specific chemotherapeutic treatment regimen (p = 0.24) was not associated with tumor progression or recurrence. Sixty-four percent of children with recurrent or progressive disease were asymptomatic, and recurrence was diagnosed by surveillance MRI alone. All children less than 2 years of age in whom the tumor was diagnosed were asymptomatic at the time of progression (p = 0.04). Thirteen percent (6 of 46) of the children had disease recurrence 5 years after initial diagnosis; all of them had undergone an initial subtotal resection. Tumor progression was associated with either homogeneous or patchy T1-weighted post–Gd administration MRI enhancement in 94% of the cases (p = 0.0001).

Conclusions

Children diagnosed with recurrent LGG may be asymptomatic at the time of recurrence. The authors' findings support the need for routine neuroimaging in a subset of children with LGGs, even when gross-total resection has been achieved, up to 5 years postdiagnosis. The authors found that T1-weighted MR images obtained before and after Gd administration alone may be sufficient to diagnose LGG recurrence and may represent an effective strategy worthy of further validation in a larger multiinstitutional cohort.

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Scott Y. Rahimi, E. Andrew Stevens, David John Yeh, Ann Marie Flannery, Haroon Fiaz Choudhri and Mark R. Lee

The atlantoaxial region has been extensively described as a spinal segment especially prone to injury in children. In this clinical review, the authors evaluate and summarize the management of 23 pediatric cases of atlantoaxial instability treated between March 1990 and October 2002. Four broad categories of atlantoaxial problems were observed—atlantoaxial rotatory subluxation in six patients, anterior–posterior atlantoaxial instability caused by ligamentous injury or congenital ligamentous laxity (10 patients), atlantoaxial fracture with or without dislocation (five patients), and atlantooccipital dislocation (two patients). Most cases (60.9%) were treated without surgical intervention, resulting in excellent outcomes; however, 21.7% of cases were treated with a cervical halo (mean patient age 72.6 months) alone for 3 months. Various techniques of surgical stabilization including transarticular screws with sublaminar wiring, trans-oral decompression with posterior plating, and laminectomy with Steinmann pin occipital–cervical fusion were used with good results. Both patients with atlantooccipital dislocation underwent immediate Locksley occipital–cervical fusion, with marked neurological improvement. Individualized case management must be based on clinical presentation, with internal fixation being the last resort.

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Soumya Mukherjee, Bhaskar Thakur, Dolin Bhagawati, Dimpu Bhagawati, Samira Akmal, Vasileios Arzoglou, John Yeh and Habib Ellamushi

Object

The authors assess the utility of routine biopsy at vertebroplasty for vertebral compression fracture (VCF) as a tool in the early detection of malignancy in presumed benign VCF.

Methods

A prospective observational study was conducted on a cohort of consecutive patients undergoing vertebroplasty over a 5-year period between April 2006 and March 2011 at the Royal London Hospital. Polymethylmethacrylate cement injection was used in every procedure. Intraoperative vertebral body biopsy was performed routinely at every level of VCF. Pain visual analog scale (VAS) scores, Oswestry Disability Index (ODI) scores, analgesic usage, and complications were recorded preoperatively and at 1 day, 1 week, 1 month, 6 months, and 1 year postoperatively.

Results

A total of 202 levels were augmented in 147 patients. The most common levels augmented were T-12 (17%), L-1 (18%), and L-4 (10%). Analysis of 184 routine vertebral biopsies in 135 patients revealed that in 86 patients with presumed osteoporosis and no prior cancer diagnosis, 4 (4.7%) had a malignant VCF. In 20 known cancer patients presumed to be in remission, 2 (10%) had a malignant VCF. Routine vertebral biopsy returned an overall cancer diagnosis rate of 5.5% (6 of 109) when combining the 2 groups (patients with no prior history of cancer or cancer thought to be in remission). In these 6 patients, history, examination, laboratory tests, and preprocedure imaging all failed to suggest malignancy diagnosed at routine biopsy. Significant reductions in pain VAS and ODI scores were evident at Day 1 and were sustained at up to 1 year postoperatively (p < 0.001). They were not dependent on the level of fracture (T3–10, T11–L2, or L3–S1) (p > 0.05), number of levels treated (single level, 2 levels, or > 2 levels) (p > 0.05), or etiology of VCF (p > 0.05). The complication rate was 6% (9 of 147). There were 5 deaths, none of which were directly related to surgery.

Conclusions

Routine vertebral biopsy performed at vertebroplasty may demonstrate cancer-related VCFs in unsuspected patients with no previous cancer diagnosis or active malignancy in patients previously thought to be in remission. This early diagnosis of cancer or relapsed disease will play an important role in expediting patients' subsequent cancer management. In cases of multiple-level VCF, the authors advocate biopsy at each level to maximize the diagnostic yield from the specimens and to avoid missing a malignancy at a single level.

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Oral Presentations

2010 AANS Annual Meeting Philadelphia, Pennsylvania May 1–5, 2010