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Aaron A. Cohen-Gadol, Dennis D. Spencer and William E. Krauss

✓ Harvey Cushing's refinement of Halsted's meticulous surgical techniques facilitated safe resection of intradural spinal tumors. Although Cushing focused his attention on brain tumors at the Peter Bent Brigham Hospital, his numerous contributions to the treatment of intradural spinal tumors include the description of these tumors' natural histories and their histological classifications. The application of his experienced intracranial techniques to the resection of spinal tumors improved outcomes. The authors review selected operative notes and sketches to demonstrate his technique in the excision of the spinal cord tumors.

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Aaron A. Cohen-Gadol, William E. Krauss and Robert J. Spinner

Chronic subarachnoid hemorrhage may cause deposition of hemosiderin on the leptomeninges and subpial layers of the neuraxis, leading to superficial siderosis (SS). The symptoms and signs of SS are progressive and fatal. Exploration of potential sites responsible for intrathecal bleeding and subsequent hemosiderin deposition may prevent disease progression. A source of hemorrhage including dural pathological entities, tumors, and vascular lesions has been previously identified in as many as 50% of patients with SS. In this report, the authors present three patients in whom central nervous system SS developed decades after brachial plexus avulsion injury. They believe that the traumatic dural diverticula in these cases may be a potential source of bleeding. A better understanding of the pathophysiology of SS is important to develop more suitable therapies.

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Aaron A. Cohen-Gadol, Patty P. Atkinson and William E. Krauss

✓ Superficial siderosis of the central nervous system is a rare progressive disease associated with hemosiderin deposition on the leptomeninges of the neuraxis. In addition to tumors and vascular lesions, dural sleeve pseudomeningoceles caused by brachial plexus avulsion injury may be the bleeding source in this disease. The authors describe a patient who underwent anterior cervical spine surgery for spinal cord compression due to the ossification of posterior longitudinal ligament. The operation was complicated by a dural tear and subsequent psedomeningocele formation. Nine years later, this patient developed superficial siderosis. The possible mechanisms involved in the development of superficial siderosis in this patient will be discussed.

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Tomohiro Inoue, Aaron A. Cohen-Gadol and William E. Krauss

✓ Almost 40 cases of spontaneous transdural spinal cord herniation have been reported in the literature. These patients often present with gait disturbance and sensory changes, and their condition is diagnosed as Brown—Séquard syndrome. The pathogenesis of this condition has remained poorly understood. In particular, there is no agreement whether the dural defect is acquired or congenital. In the reported case, a 21-year-old man presented with a 3-year history of intermittent low-pressure headaches consistent with intracranial hypotension. Eventually, the headaches resolved but he developed myelopathy due to a spinal cord herniation. In this case, the authors hypothesize that the progressive spinal cord herniation through a spontaneous dural tear sealed the site of the cerebrospinal fluid leak, causing the resolution of headaches.

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William T. Longstreth Jr., Wendy Cohen and Donald T. Reay

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Aaron A. Cohen-Gadol, Jeffrey T. Jacob, Diane A. Edwards and William E. Krauss

Object

The purpose of this study was to examine the prevalence of intracranial cavernous malformations (CMs) in a large series of predominantly Caucasian patients with spinal cord CMs. The authors also studied the natural history of spinal CMs in patients who were treated nonoperatively.

Methods

The medical records of 67 consecutive patients (32 female and 35 male patients) in whom a spinal CM was diagnosed between 1994 and 2002 were reviewed. The patients’ mean age at presentation was 50 years (range 13–82 years). Twenty-five patients underwent resection of the lesion. Forty-two patients in whom the spinal CM was diagnosed using magnetic resonance (MR) imaging were followed expectantly. Thirty-three (49%) of 67 patients underwent both spinal and intracranial MR imaging. All available imaging studies were reviewed to determine the coexistence of an intracranial CM.

Fourteen (42%) of the 33 patients with spinal CMs who underwent intracranial MR imaging harbored at least one cerebral CM in addition to the spinal lesion. Six (43%) of these 14 patients did not have a known family history of CM. Data obtained during the long-term follow-up period (mean 9.7 years, total of 319 patient-years) were available for 33 of the 42 patients with a spinal CM who did not undergo surgery. Five symptomatic lesional hemorrhages (neurological events), four of which were documented on neuroimaging studies, occurred during the follow-up period, for an overall event rate of 1.6% per patient per year. No patient experienced clinically significant neurological deficits due to recurrent hemorrhage.

Conclusions

As many as 40% of patients with a spinal CM may harbor a similar intracranial lesion, and approximately 40% of patients with coexisting spinal and intracranial CMs may have the nonfamilial (sporadic) form of the disease. Patients with symptomatic spinal CMs who are treated nonoperatively may have a small risk of clinically significant recurrent hemorrhage. The findings will aid in evaluation of surveillance images and in counseling of patients with spinal CMs, irrespective of family history.

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Aaron A. Cohen-Gadol, J. Bradley White, James J. Lynch, Gary M. Miller and William E. Krauss

Object. Thoracic synovial cysts (TSCs) are rare and are usually the subject of case reports. The authors studied the clinical manifestations, radiological aspects, and surgical treatment in a series of patients at their institution who harbored TSCs. They also review the literature to discuss the potential factors involved in the pathogenesis of this lesion.

Methods. A database search of 16,000 patients who underwent decompressive spine surgery at the Mayo Clinic (Rochester, MN) between 1976 and 2003 disclosed nine patients (0.06%) in whom a diagnosis of TSC had been made. All patients were men. The mean age at presentation was 73 ± 5 years and mean duration of symptoms was 5 ± 3 months. The mean duration of follow up was 4 ± 3 years.

The patients had no history of trauma or spine surgery. All patients had spastic paraparesis; two had urinary difficulties. Detailed neurological examination revealed myelopathy and radiculopathy with a sensory level of T10—L4. Magnetic resonance imaging revealed bilateral cysts in four patients and unilateral lesions in five. Three of the cysts were at the T-10 interspace, seven at the T-11 interspace, and three at the T-12 interspace. Seven cysts were on the right and six were on the left. Computerized tomography myelography performed in five patients revealed a gas bubble in the TSC in two patients. All patients underwent laminectomy/partial facetectomy, excision of the cyst, and decompression of the thecal sac and nerve root without any complications. None of these patients underwent a fusion. Eight patients (89%) experienced moderate to excellent relief of their preoperative signs and symptoms and one patient (11%) remained stable. There was no evidence of cyst recurrence at the site of surgery or other spinal segments at follow-up examination in any patient.

Conclusions. When compared with their lumbar and cervical spine counterparts, TSCs are exceedingly rare. Their rarity may be explained by the decreased mobility of the thoracic spinal segments. The origin of TSCs is more likely degenerative rather than traumatic. Based on their experience and the follow-up duration, surgery provided durable relief from symptoms.

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William Akard, R. Shane Tubbs, Zachary A. Seymour, William E. Hitselberger and Aaron A. Cohen-Gadol

The current state of surgery for vestibular schwannomas (VSs) is the result of a century of step-by-step technical progress by groundbreaking surgeons who transformed the procedure from its hazardous infancy and high mortality rate to its current state of safety and low morbidity rate. Harvey Cushing advocated bilateral suboccipital decompression and developed the method of intracapsular tumor enucleation. Walter Dandy supported the unilateral suboccipital approach and developed the technique of gross-total tumor resection. Microsurgical techniques revolutionized VS surgery to its current status. In this article, the authors review the early history of surgery for VSs with an emphasis on contributions from pioneering surgeons. The authors examined the Cushing Brain Tumor Registry for clues regarding the bona fide intention of Cushing for the resection of these tumors.

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Aaron A. Cohen-Gadol, Ofer M. Zikel, Cody A. Koch, Bernd W. Scheithauer and William E. Krauss

Object. Spinal meningiomas occur most frequently in older patients. They are well-circumscribed and slow-growing tumors that are associated with good patient outcomes following surgery. Spinal meningiomas occurring in younger patients may be more aggressive, with a worse prognosis. The authors present their 21-year experience with spinal meningiomas in patients younger than 50 years of age.

Methods. The authors reviewed data obtained in 40 patients (age < 50 years) treated at the Mayo Clinic, Rochester, during the past 21 years; in all cases the lesions were histologically confirmed spinal meningiomas. Five men (12.5%) and 35 women (87.5%) (mean age 34.5 ± 10.9 years) underwent 52 operations for 41 tumors. The mean follow-up duration was 82 ± 93 months (range 0–445 months). The data obtained in these patients were compared with those derived from a random control cohort of 40 patients older than age 50 years in whom spinal meningiomas were resected at the Mayo Clinic during a similar period. In this cohort, there were 33 women and seven men whose mean age was 67.1 ± 9.5 years. The mean follow-up duration for the older group was 88 ± 72.3 months (range 18–309 months).

Compared with the random cohort of older patients, younger patients there tended to have more tumors located in the cervical spine (39%) as well as a greater number of predisposing factors such as neurofibromatosis Type 2, radiation exposure, or trauma. Nine (22%) of the patients younger than 50 years of age required reoperation for residual or recurrent tumor compared with two (5%) in the older patient control group. The overall mortality rate at the completion of the study for the younger patients was 10%.

Conclusions. Spinal meningiomas in younger patients have a worse prognosis than similar tumors in older patients.

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Aaron A. Cohen-Gadol, Mark B. Dekutoski, Choll W. Kim, Lynn M. Quast and William E. Krauss

Object. The AO Universal Spine System thoracic pedicle hook design includes a fixation screw that passes obliquely through the inferior facet into the pedicle to engage in the posterior portion of the superior vertebral body endplate. This endplate screw provides additional purchase at the hook—bone interface. To determine the safety of this fixation system the authors reviewed the operative notes, radiographs, and outcomes of patients who underwent placement of endplate screws.

Methods. Thirty-six patients (16 male and 20 female patients) who required posterior thoracic instrumentation for spinal deformity (11 cases), neoplasm (15 cases), and traumatic injury (10 cases) were included in this study.

One hundred sixty-four endplate screws were placed (mean 4.3/patient) to augment pedicle hooks for posterior thoracic instrumentation. The number of instrumented levels ranged from seven to 16. The positions of the screws in relation to the pedicle, neural foramen, spinal canal, and endplate were evaluated by assessing plain radiographs and computerized tomography scans (10 cases). Eighty-two screws (56%) were in ideal position. Lateral pedicle wall perforation occurred with 51 screws (35%). Three screws violated the medial wall and nine screws violated the superior or inferior walls of the pedicle. There were no clinical sequelae associated with any of the malpositioned screws. Adequate follow-up radiographic data were not available in five patients. The mean follow-up duration was 19.8 months (range 3–61 months).

Two patients required revision surgery at 3 months and 18 months, respectively, because of hook/endplate screw displacement. There was also one case of an endplate screw fracture without hook displacement that was discovered during subsequent revision surgery. The remainder of the endplate screws and associated pedicles hooks maintained their original positions. There was no case of spinal cord, nerve root, pulmonary, or vascular injury.

Conclusions. The placement of supplemental endplate screws in conjunction with thoracic pedicle hooks can be conducted safely.