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J. Patrick Johnson, Aaron G. Filler and Duncan Q. McBride

Object

Thoracoscopic discectomy is a minimally invasive procedure simulating a thoracotomy and is an alternative to the costotransversectomy and transpedicular approaches. In recent studies authors have concluded that thoracoscopic discectomy is the preferred procedure; however, relative historical comparisons were difficult to interpret.

The authors conducted a prospective nonrandomized study in which they compared data on 36 patients undergoing thoracoscopic discectomy with eight patients undergoing thoracotomy between 1995 and 1999.

Methods

Patients affected with one- or two-level lesions underwent a thoracoscopic discectomy, and patients with three-level lesions or more underwent thoracotomy and discectomy. Data were collected on operative time, blood loss, chest tube duration, narcotic agent use, and hospital length of stay (LOS). Longer-term follow-up study of pain-related symptoms and neurological function was conducted.

Patients who underwent thoracoscopic discectomy had shorter operative times, less blood loss, a shorter period of chest tube drainage dependence, less narcotic usage, and a shorter LOS. These findings were statistically significant (p < 0.05) for narcotic usage and shorter LOS. Pain related to radiculopathy was improved by means of 75%, and no patients exprienced worsened pain. In patients with myelopathy there was an improvement of two Frankel grades in the thoracoscopic group and one Frankel grade in the thoracotomy discectomy group, but patients in the thoracotomy group were significantly worse preoperatively. One myelopathic patient from each group suffered a worsened outcome postoperatively, although this was not attributed to the method of surgery. The incidence of complications (minor and major) was 31% in the thoracoscopic group and greater than 100% (that is, more than one complication per patient) in the thoracotomy/discectomy group.

Conclusions

One advantage to thoracoscopic discectomy is its reduced incidence of morbidity compared with thoractomy, but its steep learning curve and unfamiliar surgical techniques make this procedure less practical for surgeons not performing it frequently. The more familiar costotransversectomy, transpedicular, and thoracotomy procedures remain viable alternatives for surgeons more experienced in these procedures.

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Jonathan Stuart Citow, J. Patrick Johnson, Duncan Q. McBride and Mario Ammirati

Object

Neurocysticercosis (NCC) is the most common parasitic infection of the central nervous system, and its prevalence is continuing to increase in the United States. The diagnosis of intraventricular NCC (IVNCC) may be difficult, and surgery frequently fails to resolve symptoms. A retrospective review of magnetic resonance (MR) imaging characteristics and surgery-related outcomes may improve management strategies of this disease.

Methods

The authors report the presentations, neuroimaging characteristics, surgical management, and outcomes of 30 patients with IVNCC treated over a 10-year period (mean follow-up period 4 years). Cysts were located in the lateral ventricles (five cases), the third ventricle (five cases), and the fourth ventricle (21 cases). One patient had lesions in both the lateral and fourth ventricles. Presenting symptoms were related to hydrocephalus or mass effect from the lesions.

All patients underwent computerized tomography (CT) and MR imaging of the brain. Treatment consisted of shunt implantation or primary excision of an IVNCC lesion. Outcomes after operations and reoperations were evaluated in light of enhancement characteristics on MR imaging.

Computerized tomography scanning demonstrated IVNCC lesions in 10% of cases, and MR revealed lesions in 100% of cases. In patients in whom gadolinium (Gd) enhancement of IVNCC lesions was demonstrated on MR imaging, the surgery-related failure rate was higher and patients required reoperation, and in those in whom gadolinium enhancement was absent the surgery-related failure rate was lower (64 and 19%, respectively; p < 0.0002).

Conclusions

Magnetic resonance imaging is superior to CT scanning for detecting IVNCC lesions. The absence of pericystic Gd enhancement on MR imaging is an indication for excision of the lesions. If pericystic enhancement is present, shunt surgery should be performed, and craniotomy reserved for treatment of those patients with symptomatic lesions secondary to mass effect. A treatment algorithm based on patient symptoms, cyst location, and MR imaging Gd enhancement characteristics is proposed.

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Naresh P. Patel, Neill M. Wright, William W. Choi, Duncan Q. McBride and J. Patrick Johnson

Object. Forestier Disease (FD) is a progressive skeletal disorder affecting predominantly older men. It is also known as diffuse idiopathic skeletal hyperostosis (DISH) and is characterized by massive anterior longitudinal ligament calcification that forms a bridge on the anterior border of the thoracic and subaxial cervical spine. To the authors' knowledge, retroodontoid masses associated with FD have not been described.

Methods. Five patients with FD and multilevel subaxial cervical fusion were treated for retroodontoid masses and cervicomedullary junction (CMJ) compression. There were four men and one woman (mean age 73 years, range 54–86 years). All patients suffered progressive neurological symptoms resulting from anterior compression of the CMJ.

Four patients underwent combined transoral resection of the ligamentous mass followed by an occipitocervical fusion procedure. One patient with circumferential CMJ compression underwent a posterior decompression and occipitocervical fusion. Histopathological examination of the mass showed hypertrophic degenerative fibrocartilage. Early postoperative neurological improvement was noted in all patients. The follow-up period ranged from 4 to 19 months. At the end of the follow-up period, four patients experienced neurological improvement. One patient died 3 weeks postsurgery of pulmonary complications.

Conclusions. The osseous elements of the occipitoatlantoaxial complex are not directly affected by FD. The ligamentous structures of the odontoid process, however, are exposed to significantly altered biomechanics resulting from fusion of the subaxial cervical spine associated with FD. Stress-induced compensatory ligamentous hypertrophic changes at the craniovertebral junction cause CMJ compression and subsequent neurological deterioration. This previously undescribed entity should be considered in patients with FD or DISH who present with progressive quadriparesis. Transoral decompression and posterior fusion are often needed in patients with large masses and severe progressive neurological deficits. Selected patients with smaller masses and milder neurological symptoms may be treated with posterior fusion alone.

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George A. Alsina, J. Patrick Johnson, Duncan Q. McBride, Patrick R. L. Rhoten, C. Mark Mehringer and John K. Stokes

Worldwide, cysticercosis is the most common parasitic infection of the central nervous system. In endemic regions, the incidence of neurocysticercosis (NCC) approaches 4% of the general population. The disease is predominantly intracranial, the authors of most series generally report the incidence of spinal NCC as only 1.5 to 3% of all cases. Although spinal NCC is relatively rare, it represents a distinct clinical entity that can have devastating consequences for the patient. Because of the limited size of the spinal canal, the mass effect of these lesions is poorly tolerated. Most spinal NCC occurs in the subarachnoid space where mass effect can cause spinal cord compression, although obstruction of cerebrospinal fluid pathways due to scarring of the subarachnoid space can also cause symptoms.

The authors treated six patients with spinal NCC. In five cases the lesions were located in the subarachnoid space, and in one the lesion was intramedullary. All patients with subarachnoid spinal NCC required excision of the symptomatic lesions; in two cases initial medical therapy had failed. The patient with intramedullary spinal NCC experienced mild symptoms and underwent steroid therapy. All patients experienced variably improved outcomes and were eventually ambulatory.

Medical therapy should be carefully considered in selected patients in whom symptoms are stable and nonprogressive. Surgical intervention is required when severe or progressive deficits occur to prevent permanent injury. In some patients recovery may be limited as a result of inflammatory injury to the spinal cord or arachnoidal adhesions.

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Aaron G. Filler, Jodean Haynes, Sheldon E. Jordan, Joshua Prager, J. Pablo Villablanca, Keyvan Farahani, Duncan Q. Mcbride, Jay S. Tsuruda, Brannon Morisoli, Ulrich Batzdorf and J. Patrick Johnson

Object. Because lumbar magnetic resonance (MR) imaging fails to identify a treatable cause of chronic sciatica in nearly 1 million patients annually, the authors conducted MR neurography and interventional MR imaging in 239 consecutive patients with sciatica in whom standard diagnosis and treatment failed to effect improvement.

Methods. After performing MR neurography and interventional MR imaging, the final rediagnoses included the following: piriformis syndrome (67.8%), distal foraminal nerve root entrapment (6%), ischial tunnel syndrome (4.7%), discogenic pain with referred leg pain (3.4%), pudendal nerve entrapment with referred pain (3%), distal sciatic entrapment (2.1%), sciatic tumor (1.7%), lumbosacral plexus entrapment (1.3%), unappreciated lateral disc herniation (1.3%), nerve root injury due to spinal surgery (1.3%), inadequate spinal nerve root decompression (0.8%), lumbar stenosis (0.8%), sacroiliac joint inflammation (0.8%), lumbosacral plexus tumor (0.4%), sacral fracture (0.4%), and no diagnosis (4.2%).

Open MR—guided Marcaine injection into the piriformis muscle produced the following results: no response (15.7%), relief of greater than 8 months (14.9%), relief lasting 2 to 4 months with continuing relief after second injection (7.5%), relief for 2 to 4 months with subsequent recurrence (36.6%), and relief for 1 to 14 days with full recurrence (25.4%). Piriformis surgery (62 operations; 3-cm incision, transgluteal approach, 55% outpatient; 40% with local or epidural anesthesia) resulted in excellent outcome in 58.5%, good outcome in 22.6%, limited benefit in 13.2%, no benefit in 3.8%, and worsened symptoms in 1.9%.

Conclusions. This Class A quality evaluation of MR neurography's diagnostic efficacy revealed that piriformis muscle asymmetry and sciatic nerve hyperintensity at the sciatic notch exhibited a 93% specificity and 64% sensitivity in distinguishing patients with piriformis syndrome from those without who had similar symptoms (p < 0.01).

Evaluation of the nerve beyond the proximal foramen provided eight additional diagnostic categories affecting 96% of these patients. More than 80% of the population good or excellent functional outcome was achieved.

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Matthias Oertel, Daniel F. Kelly, David McArthur, W. John Boscardin, Thomas C. Glenn, Jae Hong Lee, Tooraj Gravori, Dennis Obukhov, Duncan Q. McBride and Neil A. Martin

Object. Progressive intracranial hemorrhage after head injury is often observed on serial computerized tomography (CT) scans but its significance is uncertain. In this study, patients in whom two CT scans were obtained within 24 hours of injury were analyzed to determine the incidence, risk factors, and clinical significance of progressive hemorrhagic injury (PHI).

Methods. The diagnosis of PHI was determined by comparing the first and second CT scans and was categorized as epidural hematoma (EDH), subdural hematoma (SDH), intraparenchymal contusion or hematoma (IPCH), or subarachnoid hemorrhage (SAH). Potential risk factors, the daily mean intracranial pressure (ICP), and cerebral perfusion pressure were analyzed. In a cohort of 142 patients (mean age 34 ± 14 years; median Glasgow Coma Scale score of 8, range 3–15; male/female ratio 4.3:1), the mean time from injury to first CT scan was 2 ± 1.6 hours and between first and second CT scans was 6.9 ± 3.6 hours. A PHI was found in 42.3% of patients overall and in 48.6% of patients who underwent scanning within 2 hours of injury. Of the 60 patients with PHI, 87% underwent their first CT scan within 2 hours of injury and in only one with PHI was the first CT scan obtained more than 6 hours postinjury. The likelihood of PHI for a given lesion was 51% for IPCH, 22% for EDH, 17% for SAH, and 11% for SDH. Of the 46 patients who underwent craniotomy for hematoma evacuation, 24% did so after the second CT scan because of findings of PHI. Logistic regression was used to identify male sex (p = 0.01), older age (p = 0.01), time from injury to first CT scan (p = 0.02), and initial partial thromboplastin time (PTT) (p = 0.02) as the best predictors of PHI. The percentage of patients with mean daily ICP greater than 20 mm Hg was higher in those with PHI compared with those without PHI. The 6-month postinjury outcome was similar in the two patient groups.

Conclusions. Early progressive hemorrhage occurs in almost 50% of head-injured patients who undergo CT scanning within 2 hours of injury, it occurs most frequently in cerebral contusions, and it is associated with ICP elevations. Male sex, older age, time from injury to first CT scan, and PTT appear to be key determinants of PHI. Early repeated CT scanning is indicated in patients with nonsurgically treated hemorrhage revealed on the first CT scan.

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Daniel F. Kelly, Neil A. Martin, Rouzbeh Kordestani, George Counelis, David A. Hovda, Marvin Bergsneider, Ehud Shalmon, Duncan Q. McBride, Dena Herman and Donald P. Becker

As part of a prospective study of the cerebrovascular effects of head injury, 54 moderate and severely injured patients underwent 184 133Xe-cerebral blood flow (CBF) studies to determine the relationship between the period of maximum blood flow and outcome. The lowest blood flows were observed on the day of injury (Day 0) and the highest CBFs were documented on postinjury Days 1 to 5. Patients were divided into three groups based on CBF values obtained during this period of maximum flow: Group 1 (seven patients), CBF less than 33 ml/100 g/minute on all determinations; Group 2 (13 patients), CBF both less than and greater than or equal to 33 ml/100 g/minute; and Group 3 (34 patients), CBF greater than or equal to 33 ml/100 g/minute on all measurements. For Groups 1, 2, and 3, mean CBF during Days 1 to 5 postinjury was 25.7 ± 4, 36.5 ± 4.2, and 49.4 ± 9.3 ml/100 g/minute, respectively, and PaCO2 at the time of the CBF study was 31.4 ± 6, 32.7 ± 2.9, and 33.4 ± 4.7 mm Hg, respectively.

There were significant differences across Groups 1, 2, and 3 regarding mean age, percentage of individuals younger than 35 years of age (42.9%, 23.1%, and 76.5%, respectively), incidence of patients requiring evacuation of intradural hematomas (57.1%, 38.5%, and 17.6%, respectively) and incidence of abnormal pupils (57.1%, 61.5%, and 32.4%, respectively). Favorable neurological outcome at 6 months postinjury in Groups 1, 2, and 3 was 0%, 46.2%, and 58.8%, respectively (p < 0.05). Further analysis of patients in Group 3 revealed that of 14 with poor outcomes, six had one or more episodes of hyperemia-associated intracranial hypertension (simultaneous CBF > 55 ml/100 g/minute and ICP > 20 mm Hg). These six patients were unique in having the highest CBFs for postinjury Days 1 to 5 (mean 59.8 ml/100 g/minute) and the most severe degree of intracranial hypertension and reduced cerebral perfusion pressure (p < 0.0001).

These results indicate that a phasic elevation in CBF acutely after head injury is a necessary condition for achieving functional recovery. It is postulated that for the majority of patients, this rise in blood flow results from an increase in metabolic demands in the setting of intact vasoreactivity. In a minority of individuals, however, the constellation of supranormal CBF, severe intracranial hypertension, and poor outcome indicates a state of grossly impaired vasoreactivity with uncoupling between blood flow and metabolism.

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Daniel F. Kelly, Neil A. Martin, Rouzbeh Kordestani, George Counelis, David A. Hovda, Marvin Bergsneider, Duncan Q. McBride, Ehud Shalmon, Dena Herman and Donald P. Becker

✓ As part of a prospective study of the cerebrovascular effects of head injury, 54 moderate and severely injured patients underwent 184 133Xe—cerebral blood flow (CBF) studies to determine the relationship between the period of maximum blood flow and outcome. The lowest blood flows were observed on the day of injury (Day 0) and the highest CBFs were documented on postinjury Days 1 to 5. Patients were divided into three groups based on CBF values obtained during this period of maximum flow: Group 1 (seven patients), CBF less than 33 ml/100 g/minute on all determinations; Group 2 (13 patients), CBF both less than and greater than or equal to 33 ml/100 g/minute; and Group 3 (34 patients), CBF greater than or equal to 33 ml/100 g/minute on all measurements. For Groups 1, 2, and 3, mean CBF during Days 1 to 5 postinjury was 25.7 ± 4, 36.5 ± 4.2, and 49.4 ± 9.3 ml/100 g/minute, respectively, and PaCO2 at the time of the CBF study was 31.4 ± 6, 32.7 ± 2.9, and 33.4 ± 4.7 mm Hg, respectively.

There were significant differences across Groups 1, 2, and 3 regarding mean age, percentage of individuals younger than 35 years of age (42.9%, 23.1%, and 76.5%, respectively), incidence of patients requiring evacuation of intradural hematomas (57.1%, 38.5%, and 17.6%, respectively) and incidence of abnormal pupils (57.1%, 61.5%, and 32.4%, respectively). Favorable neurological outcome at 6 months postinjury in Groups 1, 2, and 3 was 0%, 46.2%, and 58.8%, respectively (p < 0.05). Further analysis of patients in Group 3 revealed that of 14 with poor outcomes, six had one or more episodes of hyperemia-associated intracranial hypertension (simultaneous CBF > 55 ml/100 g/minute and ICP > 20 mm Hg). These six patients were unique in having the highest CBFs for postinjury Days 1 to 5 (mean 59.8 ml/100 g/minute) and the most severe degree of intracranial hypertension and reduced cerebral perfusion pressure (p < 0.0001).

These results indicate that a phasic elevation in CBF acutely after head injury is a necessary condition for achieving functional recovery. It is postulated that for the majority of patients, this rise in blood flow results from an increase in metabolic demands in the setting of intact vasoreactivity. In a minority of individuals, however, the constellation of supranormal CBF, severe intracranial hypertension, and poor outcome indicates a state of grossly impaired vasoreactivity with uncoupling between blood flow and metabolism.