Superficial siderosis.

BACKGROUND: Superficial siderosis (SS) of the CNS is caused by repeated slow hemorrhage into the subarachnoid space with resultant hemosiderin deposition in the subpial layers of the brain and spinal cord. Despite extensive investigations, the cause of bleeding is frequently undetermined. OBJECTIVES: To review the clinical and imaging features of 30 consecutive patients with SS and provide insights into the underlying causes of subarachnoid bleeding in this disabling disorder. METHODS: The authors reviewed the medical records of 30 consecutive patients with clinical and MRI evidence of SS. RESULTS: The commonest neurologic manifestations included gait ataxia and hearing impairment. A clinical history of subarachnoid hemorrhage was relatively rare. Possible predisposing conditions were identified on history in 22 patients, the commonest being a prior trauma (15 patients). In addition to the characteristic MRI findings of SS, 18 patients had abnormalities on MRI possibly related to chronic bleeding. The most common of these was the presence of a fluid-filled collection in the spinal canal seen in 14 patients. CONCLUSIONS: A history of prior subarachnoid hemorrhage is often absent in patients with superficial siderosis (SS). A past history of trauma is common. Prior intradural surgery may be an additional risk factor. Xanthochromia or the presence of red blood cells in the CSF is a common finding. Only rarely does angiography demonstrate the bleeding source. The presence of a fluid-filled collection in the spinal canal is a common finding on MRI and is likely related to the SS. With longitudinally extensive cavities, a dynamic CT myelogram may help localize the defect and direct the site of laminectomy. Surgical repair of a dural defect, if present, should be considered. Surgical correction of bleeding should be documented by CSF examination months after surgery. Friable vessels in the dural defect are a possible source of the chronic bleeding.

Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment.

BACKGROUND: The management of unruptured intracranial aneurysms is controversial. Investigators from the International Study of Unruptured Intracranial Aneurysms aimed to assess the natural history of unruptured intracranial aneurysms and to measure the risk associated with their repair. METHODS: Centres in the USA, Canada, and Europe enrolled patients for prospective assessment of unruptured aneurysms. Investigators recorded the natural history in patients who did not have surgery, and assessed morbidity and mortality associated with repair of unruptured aneurysms by either open surgery or endovascular procedures. FINDINGS: 4060 patients were assessed-1692 did not have aneurysmal repair, 1917 had open surgery, and 451 had endovascular procedures. 5-year cumulative rupture rates for patients who did not have a history of subarachnoid haemorrhage with aneurysms located in internal carotid artery, anterior communicating or anterior cerebral artery, or middle cerebral artery were 0%, 2. 6%, 14 5%, and 40% for aneurysms less than 7 mm, 7-12 mm, 13-24 mm, and 25 mm or greater, respectively, compared with rates of 2 5%, 14 5%, 18 4%, and 50%, respectively, for the same size categories involving posterior circulation and posterior communicating artery aneurysms. These rates were often equalled or exceeded by the risks associated with surgical or endovascular repair of comparable lesions. Patients' age was a strong predictor of surgical outcome, and the size and location of an aneurysm predict both surgical and endovascular outcomes. INTERPRETATION: Many factors are involved in management of patients with unruptured intracranial aneurysms. Site, size, and group specific risks of the natural history should be compared with site, size, and age-specific risks of repair for each patient.

Clinical and radiographic features of dural arteriovenous fistula, a treatable cause of myelopathy.

OBJECTIVE: To assess presentation, imaging, treatment, and outcome of patients with myelopathy due to a dural arteriovenous fistula (DAVF). PATIENTS AND METHODS: This retrospective review identified 94 patients with DAVF surgically treated at our institution between June 1985 and December 1999. The mean ages of the 75 men and 19 women were 62.6 years and 63.0 years, respectively (range, 31-83 years). Magnetic resonance imaging was performed in 87 patients, computed tomography-myelography was performed in 37 patients, and spinal angiography was performed in all patients. Initial examination findings were retrospectively adjusted to a modified Aminoff-Logue myelopathy scale. RESULTS: Of the 94 patients, 47 presented with symptoms that worsened with erect posture or Valsalva maneuver. As myelopathy progressed, patients' symptoms increased, and 6 patients had paraplegia at presentation. The mean time from symptom onset to diagnosis was 23 months (range, 2-120 months). Magnetic resonance imaging confirmed the diagnosis in 86 patients; computed tomography-myelography was needed to confirm the fistula in 1 patient. Spinal angiography detected the fistula in all patients. Surgical obliteration of the DAVF was successful in 93 patients; in 1 patient surgery failed because the DAVF was not localized, but acrylic endovascular embolization was successful. No patient experienced permanent morbidity or mortality. Of the 94 patients, 93 improved postoperatively 1 or 2 levels based on a modified Aminoff-Logue scale. Older patients with severe long-term deficits had poor outcomes. CONCLUSIONS: The diagnosis of a DAVF seems to be delayed considerably because DAVF is not included in the differential diagnosis of myelopathy and because of clinicians' unfamiliarity with suggestive or revealing findings on diagnostic imaging. Neurodiagnostic imaging confirms the diagnosis, and spinal angiography localizes the fistula. Surgical intradural disconnection of the DAVF clinically reverses the pathophysiology. Additionally, surgical treatment is associated with low short-term morbidity, no permanent morbidity, and no mortality. If the diagnosis is made early and treatment initiated in such patients, they generally do well.

Radiation-induced meningiomas involving the orbit.

PURPOSE: To review the clinical features and outcomes of patients with radiation-induced meningiomas involving the orbit. DESIGN: Retrospective case series. PARTICIPANTS: Eight patients with radiation-induced meningiomas affecting the orbit. METHODS: Clinical and pathologic data of the patients were reviewed. MAIN OUTCOME MEASURES: Age at diagnosis, mean interval between radiation therapy and meningioma diagnosis, tumor recurrence, histologic atypia, and mean follow-up time after initial diagnosis. RESULTS: The mean age at diagnosis was 42 years (range, 21 years to 70 years). The mean interval between radiation therapy and meningioma diagnosis was 26 years (range, 3 years to 54 years). All patients underwent gross total resection or subtotal resection of the meningioma. Five tumors (62.5%) recurred, based on clinical findings and CT imaging. The mean interval between resection of the meningioma and recurrence was 3 years (range, 9 months to 9 years). Three patients (37.5%) had atypical meningiomas. One patient (12.5%) had multiple tumors. The mean follow-up interval was 7 years after initial diagnosis of the meningioma (range, 15 months to 19 years). CONCLUSIONS: This series of radiation-induced meningiomas, the first in the ophthalmic literature, illustrates the aggressive nature of this tumor.

Small cerebral aneurysms presenting with symptoms other than rupture.

BACKGROUND: Recent natural history studies have suggested that unruptured intracranial aneurysms smaller than 1 cm have a low risk of rupture. Symptomatic aneurysms may be underrepresented in natural history studies because they are preferentially treated. The authors compared the number of patients with symptoms caused by unruptured intracranial aneurysms smaller than 1 cm treated surgically at their institution with similar patients enrolled in the International Study of Unruptured Intracranial Aneurysms (ISUIA) from their institution over the same time period. METHODS: The records of all unruptured aneurysms treated surgically at the Mayo Clinic from 1980 through 1991 were reviewed. There were 97 patients with 117 unruptured aneurysms smaller than 1 cm by angiography. Aneurysms with a history of rupture or larger than 1 cm on cross-sectional imaging were excluded from analysis. The presence and characteristics of symptoms directly attributable to the aneurysm were recorded. Comparison was made with patients from the Mayo Clinic enrolled in the ISUIA retrospective natural history cohort over the same time period. RESULTS: Of the 97 patients studied, 15 presented with symptoms other than rupture (15.5%). The symptoms were third nerve deficit (seven patients), cerebral ischemia owing to emboli originating from within the aneurysm (five patients), and visual acuity loss (three patients). Eleven other aneurysms had possibly but not definitively caused symptoms; these were considered asymptomatic. No patient from the Mayo Clinic enrolled in the retrospective cohort of the ISUIA had a symptomatic aneurysm smaller than 1 cm on both angiography and cross-sectional imaging. CONCLUSIONS: Unruptured intracranial aneurysms smaller than 1 cm occasionally present with neurologic symptoms. These symptoms are typically owing to mass effect on the second and third cranial nerves or cerebral ischemia as a result of emboli originating from within the aneurysm. Patients with symptomatic unruptured aneurysms less than 1 cm at the Mayo Clinic were preferentially treated. Although existing natural history data may be applied to most unruptured aneurysms, small symptomatic aneurysms may be underrepresented in natural history studies.

Remote hemorrhage.

The authors report a case of infra- and supratentorial intracerebral hemorrhage complicating the postoperative course of a patient who had undergone surgical removal of a cervical schwannoma with an hourglass configuration. To their knowledge, this is the first case in which this neurosurgical procedure was followed by such a complication. Possible mechanisms are discussed; however, pathological events leading to this complication are unclear. The development of new neurological deficits not attributable to the surgical procedure should suggest this possibility.

100 years of neurological surgery at the Mayo Clinic.

The practice of neurological surgery at the Mayo Clinic began as early efforts were undertaken by Drs. Charles Mayo and Emil Beckman, and surgical procedures were performed for trauma, infection, tumor, epilepsy, and hemorrhage. In 1919, the Section of Neurologic Surgery was established, with Alfred W. Adson as its first chair. Subsequently, Drs. Winchell McK. Craig, J. Grafton Love, Collin S. MacCarty, Ross H. Miller, and Thoralf M. Sundt, Jr., followed as eminent chairmen. Beginning with a modest number of cases per year, the neurosurgical service at the Mayo Clinic has grown to become one of the largest in North America. Under the current leadership of Dr. David G. Piepgras, approximately 3200 surgical procedures spanning the spectrum of subspecialties are performed each year by a staff of 10 neurosurgeons. This article traces neurosurgery at the Mayo Clinic, including several persons who contributed to its achievements over the past century.

Hypopituitarism caused by intrasellar aneurysms.

OBJECTIVE: To determine the prevalence, clinical presentation, and outcome of hypopituitarism due to an intrasellar aneurysm. PATIENTS AND METHODS: We performed a retrospective review of Mayo Clinic, Rochester, Minn, medical records from 1950 through 1995. We calculated the prevalence of hypopituitarism, characterized the clinical presentation, and evaluated postoperative outcomes. RESULTS: Of 4087 patients with a diagnosis of hypopituitarism, 7 had hypopituitarism due to an intrasellar aneurysm, accounting for a prevalence of 0.17%. Adrenal, thyroid, and gonadal deficiencies were observed in 7, 6, and 5 patients, respectively. The prolactin level was increased in the 2 patients in whom it was measured. No patient had diabetes insipidus. All had visual impairment. In 5 patients an intrasellar aneurysm of the internal carotid artery was diagnosed preoperatively based on 1 or more imaging procedures. In the other 2 patients (1 with an internal carotid artery aneurysm and 1 with an anterior cerebral artery aneurysm), the diagnosis was made at surgical exploration. Four patients underwent a surgical procedure: 2 had direct packing of the aneurysm, and 2 had a bypass with proximal carotid occlusion or aneurysm trapping. Pituitary function remained unchanged postoperatively. CONCLUSION: An intrasellar aneurysm is a rare cause of hypopituitarism (0.17% of cases). Preoperative diagnosis is essential for successful surgical outcomes. Hypopituitarism is usually permanent.

Occult rupture of a giant vertebral artery aneurysm following proximal occlusion and intrasaccular thrombosis. Case report.

The authors describe a unique clinicopathological phenomenon in a patient who presented with an unruptured giant vertebral artery aneurysm and who underwent endovascular proximal occlusion of the parent artery followed, several days later, by surgical trapping of the aneurysm after delayed subarachnoid hemorrhage (SAH). The intraoperative finding of a thrombus extruding from the wall of the aneurysm at a site remote from the origin of the SAH underscores the possibility that occult rupture of an aneurysmal sac can occur in patients with thrombosed giant aneurysms.

The effect of changing transfusion practice on rates of perioperative stroke and myocardial infarction in patients undergoing carotid endarterectomy: a retrospective analysis of 1114 Mayo Clinic patients. Mayo Perioperative Outcomes Group.

OBJECTIVE: To evaluate changes in the institution's red blood cell (RBC) transfusion practice during the past 15 years and the influence of these changes on neurologic or cardiac morbidity after carotid endarterectomy. PATIENTS AND METHODS: Based on a retrospective analysis of the Mayo Clinic database, 1,114 patients who underwent carotid endarterectomy were stratified into 1 of 2 groups: (1) 1980 to 1985 (ie, pre-human immunodeficiency virus screening, early-practice group [n=552]) and (2) 1990 to 1995 (ie, recent-practice group [n=562]). Data were compared between time periods using the chi2 test for categorical variables and the rank sum test for continuous variables. Logistic regression was used to assess the association between perioperative transfusion practice and the occurrence of stroke or myocardial infarction. Two-tailed P values < or = 05 were considered statistically significant. RESULTS: Patients in the recent-practice group were significantly older (mean +/- SD age, 69.6 +/- 8.7 years) vs 65.9 +/- 8.3 years in the early-practice group (P<.001). The proportion of patients receiving perioperative RBC transfusion decreased dramatically from 72.9% in 1980-1985 to 8.7% in 1990-1995 (P<.001). Additionally, the mean +/- SD number of RBC units transfused decreased from 1.10 +/- 1.30 U in 1980-1985 to 0.27 +/- 1.22 U in 1990-1995 (P<.001). Mean +/- SD discharge hemoglobin concentration decreased from 13.7 +/- 1.4 g/dL in 1980-1985 to 11.8 +/- 1.5 g/dL in 1990-1995 (P<.001). Rates of perioperative stroke and myocardial infarction did not differ between the 2 time periods (early-practice group vs recent-practice group: stroke, 5.1% vs 3.6% [P=.22]; myocardial infarction, 1.5% vs 2.3% [P=.29]). CONCLUSIONS: Our results suggest that elderly patients undergoing carotid endarterectomy (ie, individuals known to be at high risk for cerebral and cardiac ischemia) can tolerate modest perioperative anemia despite a considerable change in the institution's transfusion practice (lower "transfusion trigger," the hemoglobin concentration or hematocrit value below which RBC transfusion is indicated).

Cerebrovascular manifestations in 321 cases of hereditary hemorrhagic telangiectasia.

BACKGROUND AND PURPOSE: Patients with hereditary hemorrhagic telangiectasia (HHT) are at risk for developing cerebral vascular malformations and pulmonary arteriovenous fistulae. We assessed the risk of neurological dysfunction from these malformations and fistulae. METHODS: Three hundred twenty-one consecutive patients with HHT seen at a single institution over a 20-year period were studied. Any evidence of prior neurological symptoms or presence of an intracranial vascular malformation was recorded. All cases of possible cerebral arteriovenous malformation were confirmed by conventional arteriography. RESULTS: Twelve patients (3.7%) had a history of cerebral vascular malformations. Ten patients had arteriovenous malformations, 1 had a dural arteriovenous fistula, and 1 had a cavernous malformation. Seven patients (2.1%) presented with intracranial hemorrhage, 2 presented with seizures alone, and 3 were discovered incidentally. The average age at the time of symptomatic intracranial hemorrhage was 25.4 years. All patients with a history of intracranial hemorrhage were classified as Rankin grade I or II at a mean follow-up interval of 6.0 years. A history of cerebral infarction or transient ischemic attack was found in 29.6% of patients with HHT and a pulmonary arteriovenous fistula. CONCLUSIONS: The risk of intracranial hemorrhage is low among people with HHT. Furthermore, a majority of these patients have a good functional outcome after hemorrhage. The data do not suggest a compelling indication for routine screening of patients with HHT for asymptomatic cerebral vascular malformations. By comparison, pulmonary arteriovenous fistulae are a much more frequent cause of neurological symptoms in this population.

Ischemic complications of surgery for anterior choroidal artery aneurysms.

OBJECT: Anterior choroidal artery (AChA) aneurysms account for 4% of all intracranial aneurysms. The surgical approach is similar to that for other supraclinoid carotid artery lesions, but surgery may involve a higher risk of debilitating ischemic complications because of the critical territory supplied by the AChA. METHODS: Between 1968 and 1999, 51 AChA aneurysms in 50 patients were treated using craniotomy and clipping at the Mayo Clinic. There were 22 men (44%) and 28 women (56%) whose average age was 53 years (range 27-79 years). Twenty-four AChA aneurysms (47%) had hemorrhaged; nine patients (18%) had subarachnoid hemorrhage from another aneurysm. Three AChA aneurysms (6%) were associated with symptoms other than rupture. Forty-one patients (82%) achieved a Glasgow Outcome Scale (GOS) score of 4 or 5 at long-term follow up. The surgical mortality rate was 4%, and major surgical morbidity (GOS < or = 3) was 10%. Eight patients (16%) had clinically and computerized tomography-demonstrated AChA territory infarcts. Five of these strokes manifested in a delayed fashion 6 to 36 hours after the operation, and progressed from mild to complete deficit over hours. In 41 patients the aneurysm arose from the internal carotid artery adjacent to the AChA, and in nine patients the aneurysm arose directly from the origin of the AChA itself; four of these nine patients had postoperative infarction. CONCLUSIONS: Surgical treatment of AChA aneurysms involves a significant risk of debilitating ischemic complications. Most postoperative strokes occur in a delayed fashion, offering a potential therapeutic window. Patients with aneurysms arising from the AChA itself have an extremely high risk for postoperative stroke.

Mechanisms of intracerebral hemorrhage after carotid endarterectomy.

OBJECT: Intracerebral hemorrhage (ICH) is an uncommon complication of carotid endarterectomy (CEA), and carries a high rate of mortality and morbidity. Traditionally, attention has been focused on the cerebral hyperperfusion syndrome (HPS) as the leading cause of ICH after CEA. Other mechanisms, such as a perioperative cerebral ischemic event, cerebral infarction, and use of postoperative anticoagulation therapy, may also be important. METHODS: The authors performed a retrospective case control study to identify factors leading to ICH after CEA. Records of CEAs performed over the past 10 years at the Mayo Clinic were searched for occurrences of ICH within 30 days of the procedure. The relationship of ICH to known cerebrovascular risk factors, perioperative electroencephalographic studies, and 133Xe cerebral blood flow (CBF) studies was compared with that in a control group. Hyperperfusion was defined as hypertension with symptoms of either severe headache, seizures, or confusion, or a doubling of intraoperative CBF values. The clinical history and imaging of ischemic events and the ICH were carefully reviewed to determine the possible underlying mechanism(s). Twelve (0.4%) of 2747 patients who underwent CEAs suffered a postoperative ICH. A doubling of CBF values was found in five of eight cases in which CBF studies were performed, and occurred more commonly in the patients with ICH than in controls. Clinical symptoms of the HPS were less common (three cases). A perioperative cerebral ischemic event (four cases) and anticoagulation therapy (six cases) were other contributors to a subsequent ICH. Seven of the 12 patients with ICHs died and five achieved a moderate outcome. CONCLUSIONS: An ICH following CEA is an unusual complication that occurs in the setting of hyperperfusion, perioperative cerebral ischemia, anticoagulation therapy, or multiple mechanisms. Identification of CBF doubling at surgery may assist in identifying patients at risk for ICH following CEA.

Remote cerebellar hemorrhage after supratentorial surgery.

OBJECTIVE: Remote cerebellar hemorrhage (RCH) is an infrequent and poorly understood complication of supratentorial neurosurgical procedures. We retrospectively compared 42 patients who experienced RCH with a case-matched control cohort, to delineate risk factors associated with the occurrence of this complication. METHODS: Between 1988 and 2000, 42 patients experienced RCH after supratentorial neurosurgical procedures at our institution. Diagnoses were made on the basis of postoperative computed tomographic or magnetic resonance imaging findings in all cases. The medical records for these patients were reviewed and compared with those for a control cohort of 43 patients, matched for age, sex, surgical lesion, and type of craniotomy, who were treated during the same period. RESULTS: RCH most commonly occurred after frontotemporal craniotomies for unruptured aneurysm repair or temporal lobectomy and was frequently an incidental finding on postoperative computed tomographic scans. However, some cases of RCH were associated with significant morbidity, and two patients died. Preoperative aspirin use and elevated intraoperative systolic blood pressure were significantly associated with RCH (P = 0.026 and P = 0.036, respectively). Pathological findings for two cases demonstrated hemorrhagic infarctions in both. CONCLUSION: RCH most commonly follows supratentorial neurosurgical procedures, performed with the patient in the supine position, that involve opening of cerebrospinal fluid cisterns or the ventricular system (such as unruptured aneurysm repair or temporal lobectomy). Preoperative aspirin use and moderately elevated intraoperative systolic blood pressure are potentially modifiable risk factors associated with the development of RCH. Although RCH can cause death or major morbidity, most cases are asymptomatic or exhibit a benign course. Cerebellar "sag" as a result of cerebrospinal fluid hypovolemia, causing transient occlusion of superior bridging veins within the posterior fossa and consequent hemorrhagic venous infarction, is the most likely pathophysiological cause of RCH.

Absent headache despite CSF volume depletion (intracranial hypotension).

CSF volume depletions, whether from leak or shunt overdrainage, typically cause low CSF opening pressures, orthostatic headaches, and diffuse pachymeningeal gadolinium enhancement on MRI. The authors report three patients-two with overdraining CSF shunts and one with proven CSF leak-with the typical pachymeningeal enhancement but without headaches. In CSF leaks and CSF shunt overdrainage, like MRI abnormalities and CSF alterations, the clinical features also show considerable variability. The independent variable remains the CSF volume depletion.

Perspectives on training standards in neuroendovascular therapeutics.

Endovascular surgical neuroradiology has become a discipline in its own right, supported by a substantial and growing body of knowledge. In recognition of its emergence as a new field of study and practice, representatives from the two most influential founding disciplines, neurosurgery and neuroradiology, have defined a set of training standards, which ensure that practitioners learn both the procedures and their theoretical foundations.