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Surgical treatment of syringomyelia

Favorable results with syringoperitoneal shunting

Nicholas M. Barbaro, Charles B. Wilson, Philip H. Gutin and Michael S. B. Edwards

✓ The authors reviewed the clinical findings, radiological evaluation, and operative therapy of 39 patients with syringomyelia. Syringoperitoneal (SP) shunting was used in 15 patients and other procedures were used in 24 patients. Follow-up periods ranged from 1½ to 12 years. During the period of this study, metrizamide myelography in conjunction with early and delayed computerized tomography scanning replaced all other diagnostic procedures in patients with syringomyelia. Preoperative accuracy for the two procedures was 87%.

The most common symptoms were weakness (79%), sensory loss (67%), pain (38%), and leg stiffness (28%). Surgery was most effective in stabilizing or alleviating pain (100%), sensory loss (81%), and weakness (74%); spasticity, headache, and bowel or bladder dysfunction were less likely to be reversed. Approximately 80% of patients with idiopathic and posttraumatic syringomyelia and 70% of those with arachnoiditis improved or stabilized. Better results were obtained in patients with less severe neurological deficits, suggesting the need for early operative intervention. A higher percentage of patients had neurological improvement with SP shunting than with any other procedure, especially when SP shunting was the first operation performed. Patients treated with SP shunts also had the highest complication rate, most often shunt malfunction. These results indicate that SP shunting is effective in reversing or arresting neurological deterioration in patients with syringomyelia.

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Brian T. Andrews, Philip R. Weinstein, Mark L. Rosenblum and Nicholas M. Barbaro

✓ Five patients had intradural arachnoid cysts of the thoracic spinal canal associated with syringomyelia or posttraumatic intramedullary spinal cord cysts. Three cases were diagnosed 6 to 18 years after spinal surgery and two 14 to 17 years after spinal cord trauma. In each case, delayed progression of symptoms led to the identification of the lesions. The diagnosis was assisted by the use of myelography and delayed computerized tomography scanning in two cases and by magnetic resonance imaging in all five. In each case, the arachnoid cyst appeared to compress the spinal cord or nerve roots; in three cases, the syrinx cavities appeared to exert a significant mass effect. In the two trauma-related cases, the intramedullary cysts were small and may have represented areas of cystic myelomalacia. In four cases, intraoperative real-time ultrasonography helped to localize the arachnoid and intramedullary cavities. All five patients were treated by fenestration of the arachnoid cyst; additional peritoneal shunting of the cyst was performed in one case and of the intramedullary cavity in three. In one patient, the two lesions appeared to have a balancing effect; after drainage of the arachnoid cyst, the syrinx cavity expanded and had to be treated separately. The neurological deficits were reduced in four patients and stabilized in one. Intradural arachnoid cysts and intramedullary cysts may occur together as a late complication of spinal surgery or spinal cord trauma, and either or both lesions may cause delayed neurological deterioration.

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William G. Obana, Kenneth D. Laxer, Philip H. Cogen, John A. Walker, Richard L. Davis and Nicholas M. Barbaro

✓ Frontal opercular gliosis in the dominant hemisphere caused medically refractory partial epilepsy in two patients. Both patients were aphasic during their seizures, but otherwise had normal speech. Magnetic resonance images showed well-demarcated lesions resembling tumors in each patient; on heavily T2-weighted images, the lesions were hyperintense compared with normal brain. Cortical mapping with subdural grids localized speech to the area of the lesions; therefore, the resections were performed under local anesthesia and speech was tested throughout the procedure. Postoperatively, both patients were seizure-free and had no new neurological deficits. Well-demarcated lesions, even in the dominant operculum, can be safely removed in patients with medically refractory partial epilepsy.

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Adam N. Mamelak, Nicholas M. Barbaro, John A. Walker and Kenneth D. Laxer

✓ Corpus callosotomy is valuable for controlling medically intractable generalized seizures in appropriate patients, but postoperative development of language disorders, neuropsychological impairment, and motor dysfunction have all been noted. The extent of callosum resection has been implicated as a possible determinant of outcome, but this hypothesis has not been formally tested. Analysis of the records of all patients who underwent corpus callosotomy at the University of California, San Francisco, from 1986 to 1991 showed that, of 15 patients who underwent anterior or complete callosotomy, seven were entirely or nearly seizure-free, four had at least a 50% reduction in seizure frequency, and four had no change.

To determine callosal size and extent of callosotomy, preoperative and postoperative magnetic resonance images were measured with computer-based planimetry. Seizure outcome was not significantly associated with preoperative callosal size or extent of callosotomy. Intelligence quotient scores did not change significantly after callosotomy. No severe neuropsychological deficits developed after anterior or complete callosotomy, even in patients with mixed cerebral dominance or bilateral language representation. These results indicate that division of the anterior one-half to two-thirds of the corpus callosum is nearly as effective as more extensive anterior sectioning or complete callosotomy in reducing drop-attack and generalized tonic-clonic seizures in appropriate patients, and that the extent of callosotomy is not an important factor on outcome when at least 50% to 65% of the callosum is divided. Mixed cerebral dominance and other unusual patterns of language and memory organization do not appear to increase the postoperative risk for neuropsychological deficits, regardless of the extent of anterior section.

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Lilly Tang, Mary Mantle, Paul Ferrari, Hagen Schiffbauer, Howard A. Rowley, Nicholas M. Barbaro, Mitchel S. Berger and Timothy P. L. Roberts

Object. The aim of this study was to evaluate the spatial accuracy of interictal magnetoencephalography (MEG) in localizing the primary epileptogenic focus in comparison with alternative MEG-derived estimates such as ictal onset recording or sensory mapping of the periphery where seizures manifest.

Methods. During this retrospective study of 12 patients with epilepsy who had undergone successful magnetic source (MS) imaging with the aid of a dual 37-channel biomagnetometer as well as simultaneous MEG/electroencephalography (EEG) recordings, ictal events were observed in five patients and quantitative comparisons of interictal spike and ictal seizure onset source localizations were made. In the eight patients who had presented with sensorimotor seizure, source localization of cortical sites concordant with seizure foci was determined using somatosensory functional mapping, and the results were quantitatively compared with interictal spike source localizations.

Interictal spike sources demonstrated on MEG localized to the same region as the corresponding ictal event or somatosensory source localizations. The mean distance between the ictal foci and interictal spike sources was 1.1 ± 0.3 cm. Results of functional somatosensory mapping in patients with sensorimotor seizures demonstrated that seizure sources consistently colocalized with interictal MEG spike sources, with a mean distance of 1.5 ± 0.4 cm. No systematic directional bias was observed. Interictal sources tended to be tightly clustered, and the mean ellipsoid volume, defined by one standard deviation of the source spatial coordinates, was 1 cm3.

Conclusions. Interictal spike localizations on MEG were concordant with ictal and, where relevant, functional somatosensory mapping localizations. These findings support the interpretation of interictal spikes on MEG as a useful and effective noninvasive method for localizing primary seizure foci.

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Devin K. Binder, Justin S. Smith and Nicholas M. Barbaro

Object

The authors report on the treatment of primary brachial plexus tumors in 25 patients at the University of California, San Francisco. They compare their findings with those obtained in similar series.

Methods

The authors reviewed the electronic and medical records, radiological images, operative reports, and pathological findings in 25 consecutive cases of primary brachial plexus tumors. Cases of metastatic lesions or adjacent neoplasms extending into and involving the brachial plexus were excluded.

At presentation patients ranged in age from 19 to 71 years (mean 47 ±15 years), and neurofibromatosis was present in eight patients (32%). Presenting signs and symptoms included palpable mass (60%), numbness/paresthesias (44%), radiating pain (44%), local pain (16%), and weakness (12%). Duration of symptoms ranged from 2 months to 10 years. Neuroimaging revealed lesions ranging widely in size (volume ~1 to >100 ml). Pathological diagnoses included schwannoma (15 [60%]), neurofibroma (five [20%]), malignant peripheral nerve sheath tumor (four [16%]), and desmoid tumor (one [4%]).

Conclusions

Primary tumors arising in the brachial plexus are rare. Careful workup, surgical technique, and attention to pathological diagnosis optimize management.

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Jason S. Cheng, Rene O. Sanchez-Mejia, Mary Limbo, Mariann M. Ward and Nicholas M. Barbaro

Object

Trigeminal neuralgia (TN) is a painful disorder that frequently causes lancinating, electrical shock–like pain in the trigeminal distribution. Common surgical treatments include microvascular decompression (MVD), radio-surgery, and radiofrequency ablation, and complete pain relief is generally achieved with a single treatment in 70 to 85% of cases for all modalities. In a subset of patients with multiple sclerosis (MS), however, the rates of surgical treatment failure and the need for additional procedures are significantly increased compared with those in patients without MS. In this study the authors report their experience with a cohort of 11 patients with TN who also had MS, and assess the efficacy of MVD, gamma knife surgery (GKS), and radiofrequency ablation in achieving complete or partial long-term pain relief.

Methods

Eleven patients with TN and MS who were treated by the senior author (N.B.) at the University of California, San Francisco were included in this study. All patients underwent GKS and/or radiofrequency ablation, and four received MVD. A detailed clinical history and intraoperative findings were recorded for each patient and frequent follow-up evaluations were performed, with a mean follow-up duration of 40.6 months (range 1–96 months). Pain was assessed for each patient by using the Barrow Neurological Institute scale (Scores I–V).

Conclusions

Achieving complete pain relief in patients with TN and MS required significantly more treatments compared with all other patients with TN who did not have MS (p = 0.004). Even when compared with a group of 32 patients who had highly refractory TN, the cohort with MS required significantly more treatments (p = 0.05). Radiosurgery proved to be an effective procedure and resulted in fewer retreatments and longer pain-free intervals compared with MVD or radiofrequency ablation.

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Rene O. Sanchez-Mejia, Mary Limbo, Jason S. Cheng, Joaquin Camara, Mariann M. Ward and Nicholas M. Barbaro

Object

Trigeminal neuralgia (TN) is characterized by paroxysmal lancinating pain in the trigeminal nerve distribution. When TN is refractory to medical management, patients are referred for microvascular decompression (MVD), radiofrequency ablation, or radiosurgery. After the initial treatment, patients may have refractory or recurrent symptoms requiring retreatment. The purpose of this study was to determine what factors are associated with the need for retreatment and which modality is most effective.

Methods

To define this population further, the authors evaluated a cohort of patients who required retreatment for TN. The mean follow-up periods were 51 months from the first treatment and 23 months from the last one, and these were comparable among treatment groups.

Conclusions

Trigeminal neuralgia can recur after neurosurgical treatment. In this study the authors demonstrate that the number of patients requiring retreatment is not negligible. Lower retreatment rates were seen in patients who initially underwent radiosurgery, compared with those in whom MVD or radiofrequency ablation were performed. Radiosurgery was more likely to be the final treatment for recurrent TN regardless of the initial treatment. After retreatment, the majority of patients attained complete or very good pain relief. Pain relief after retreatment correlates with postoperative facial numbness.