The diploic venous system: surgical anatomy and neurosurgical implications.

OBJECT: There are few systematic investigations of the dissected surgical anatomy of the diploic venous system (DVS) in the neuroanatomical literature. The authors describe the DVS relative to different common neurosurgical approaches. Knowledge of this system can help avoid potential sources of unacceptable bleeding and may impact healing of the cranium. METHODS: Using a high-speed drill with a 2-mm bit, the authors removed the outer layer of the compact bone in the skull to expose the DVS in 12 formalin-fixed cadaver heads. Pterional, supraorbital, and modified orbitozygomatic craniotomies were performed to delineate the relationship of the DVS. RESULTS: The draining point of the frontal diploic vein (FDV) was located near the supraorbital notch. The draining point of the anterior temporal diploic vein (ATDV) was located in all pterional areas; the draining point of the posterior temporal diploic vein (PTDV) was located in all asterional areas. The PTDV was the dominant diploic vessel in all sides. The FDV and ATDV could be damaged during supraorbital, modified orbitozygomatic, and pterional craniotomies. The anterior DVS connected with the sphenoparietal and superior sagittal sinus (SSS). The posterior DVS connected with the transverse and sigmoid sinuses and was the dominant diploic vessel in all 24 sides. Of all the major diploic vessels, the location and pattern of distribution of the FDV were the most constant. The parietal bone contained the most diploic vessels. No diploic veins were found in the area delimited by the temporal squama. CONCLUSIONS: The pterional, orbitozygomatic, and supraorbital approaches place the FDV and ATDV at risk. The major anterior diploic system connects the SSS with the sphenoparietal sinus. The posterior diploic system connects the SSS with the transverse and sigmoid sinuses.

Ten-year analysis of saccular aneurysms in the Barrow Ruptured Aneurysm Trial.

OBJECTIVE: The authors present the 10-year results of the Barrow Ruptured Aneurysm Trial (BRAT) for saccular aneurysms. The 1-, 3-, and 6-year results of the trial have been previously reported, as have the 6-year results with respect to saccular aneurysms. This final report comparing the safety and efficacy of clipping versus coiling is limited to an analysis of those patients presenting with subarachnoid hemorrhage (SAH) from a ruptured saccular aneurysm. METHODS: In the study, 362 patients had saccular aneurysms and were randomized equally to the clipping and the coiling cohorts (181 each). The primary outcome analysis was based on the assigned treatment group; poor outcome was defined as a modified Rankin Scale (mRS) score > 2 and was independently adjudicated. The extent of aneurysm obliteration was adjudicated by a nontreating neuroradiologist. RESULTS: There was no statistically significant difference in poor outcome (mRS score > 2) or deaths between these 2 treatment arms during the 10 years of follow-up. Of 178 clip-assigned patients with saccular aneurysms, 1 (< 1%) was crossed over to coiling, and 64 (36%) of the 178 coil-assigned patients were crossed over to clipping. After the initial hospitalization, 2 of 241 (0.8%) clipped saccular aneurysms and 23 of 115 (20%) coiled saccular aneurysms required retreatment (p < 0.001). At the 10-year follow-up, 93% (50/54) of the clipped aneurysms were completely obliterated, compared with only 22% (5/23) of the coiled aneurysms (p < 0.001). Two patients had documented rebleeding, both died, and both were in the assigned and treated coiled cohort (2/83); no patient in the clipped cohort (0/175) died (p = 0.04). In 1 of these 2 patients, the hemorrhage was not from the target aneurysm but from an incidental basilar artery aneurysm, which was coiled at the same time. CONCLUSIONS: There was no significant difference in clinical outcomes between the 2 assigned treatment groups as measured by mRS outcomes or deaths. Clinical outcomes in the patients with posterior circulation aneurysms were better in the coiling group at 1 year, but after 1 year this difference was no longer statistically significant. Rates of complete aneurysm obliteration and rates of retreatment favored patients who actually underwent clipping compared with those who underwent coiling.Clinical trial registration no.: NCT01593267 (clinicaltrials.gov).

Analysis of saccular aneurysms in the Barrow Ruptured Aneurysm Trial.

OBJECTIVE The Barrow Ruptured Aneurysm Trial (BRAT) is a prospective, randomized trial in which treatment with clipping was compared to treatment with coil embolization. Patients were randomized to treatment on presentation with any nontraumatic subarachnoid hemorrhage (SAH). Because all other randomized trials comparing these 2 types of treatments have been limited to saccular aneurysms, the authors analyzed the current BRAT data for this subgroup of lesions. METHODS The primary BRAT analysis included all sources of SAH: nonaneurysmal lesions; saccular, blister, fusiform, and dissecting aneurysms; and SAHs from an aneurysm associated with either an arteriovenous malformation or a fistula. In this post hoc review, the outcomes for the subgroup of patients with saccular aneurysms were further analyzed by type of treatment. The extent of aneurysm obliteration was adjudicated by an independent neuroradiologist not involved in treatment. RESULTS Of the 471 patients enrolled in the BRAT, 362 (77%) had an SAH from a saccular aneurysm. Patients with saccular aneurysms were assigned equally to the clipping and the coiling cohorts (181 each). In each cohort, 3 patients died before treatment and 178 were treated. Of the 178 clip-assigned patients with saccular aneurysms, 1 (1%) was crossed over to coiling, and 64 (36%) of the 178 coil-assigned patients were crossed over to clipping. There was no statistically significant difference in poor outcome (modified Rankin Scale score > 2) between these 2 treatment arms at any recorded time point during 6 years of follow-up. After the initial hospitalization, 1 of 241 (0.4%) clipped saccular aneurysms and 21 of 115 (18%) coiled saccular aneurysms required retreatment (p < 0.001). At the 6-year follow-up, 95% (95/100) of the clipped aneurysms were completely obliterated, compared with 40% (16/40) of the coiled aneurysms (p < 0.001). There was no difference in morbidity between the 2 treatment groups (p = 0.10). CONCLUSIONS In the subgroup of patients with saccular aneurysms enrolled in the BRAT, there was no significant difference between modified Rankin Scale outcomes at any follow-up time in patients with saccular aneurysms assigned to clipping compared with those assigned to coiling (intent-to-treat analysis). At the 6-year follow-up evaluation, rates of retreatment and complete aneurysm obliteration significantly favored patients who underwent clipping compared with those who underwent coiling. Clinical trial registration no.: NCT01593267 (clinicaltrials.gov).

Subarachnoid hemorrhage due to isolated spinal artery aneurysm in four patients.

Spinal artery aneurysms are usually found with arteriovenous malformations or other entities that increase hemodynamic stress. Isolated spinal artery aneurysms are rare. Four patients who presented with the acute onset of lower back pain underwent MR imaging, which revealed spinal subarachnoid hemorrhage. In all patients, work-up yielded a diagnosis of isolated spinal aneurysm, and operative treatment was successful. In the appropriate clinical setting, spinal aneurysm should be considered as a possible cause of spinal subarachnoid hemorrhage.

Incidence of superficial sylvian vein compromise and postoperative effects on CT imaging after surgical clipping of middle cerebral artery aneurysms.

BACKGROUND AND PURPOSE: Dissection and retraction of the sylvian fissure can cause venous insufficiency and may be an important contributor to postoperative edema or hemorrhage after clipping of a middle cerebral artery (MCA) aneurysm. The incidence of changes in the superficial middle cerebral vein (SMCV) and adjacent veins and whether such changes increase the amount of edema or hemorrhage on postoperative CT is the focus of this study. METHODS: Pre- and postoperative angiograms of 100 consecutive patients with MCA aneurysms treated by craniotomy and clipping were compared to determine the postoperative incidence of changes involving the SMCV. CTs from the normal and abnormal postoperative venous groups were compared to determine the amount of edema or presence of parenchymal hemorrhage. RESULTS: Postoperatively, 31 (31%) SMCVs were altered, 20 to a minor or moderate degree. Eleven cases were pronounced. In 9 (9%) cases, the SMCV was completely obscured or failed to fill on postoperative angiography. More edema (observer 1, P < .0002; observer 2, P < .0006) and small brain parenchymal hemorrhages (observer 1, P < .00003; observer 2, P < .00001) were found on the postoperative CT images of the group whose SMCVs were altered than those that were unchanged. CONCLUSIONS: Neurosurgeons and neuroradiologists should be attentive to changes in the SMCV and adjacent venous structures to optimize outcomes of procedures involving the sylvian fissure.

The Barrow Ruptured Aneurysm Trial: 6-year results.

OBJECT: The authors report the 6-year results of the Barrow Ruptured Aneurysm Trial (BRAT). This ongoing randomized trial, with the final goal of a 10-year follow-up, compares the safety and efficacy of surgical clip occlusion and endovascular coil embolization in patients presenting with subarachnoid hemorrhage (SAH) from a ruptured aneurysm. The 1- and 3-year results of this trial have been previously reported. METHODS: In total, 500 patients with an SAH met the entry criteria and were enrolled in the study. Of these patients, 471 were randomly assigned to the treatments: 238 to surgical clipping and 233 to endovascular coiling. Six patients who died before treatment and 57 patients with nonaneurysmal SAHs were excluded, leaving a total of 408 patients who underwent clipping (209 assigned) or coiling (199 assigned). Whether to treat patients within the assigned group or to cross over patients to the other group was at the discretion of the treating physician; 38% (75/199) of the patients assigned to coiling were crossed over to clipping and 1.9% (4/209) assigned to clipping were crossed over to coiling. The outcome data were collected by a dedicated nurse practitioner. The primary outcome analysis was based on the assigned treatment group; poor outcome was defined as a modified Rankin Scale (mRS) score > 2 and was independently adjudicated. Six years after randomization, 336 (82%) of 408 patients who had been treated were available for examination. RESULTS: On the basis of an mRS score of > 2, and similar to the results at the 3-year follow-up, no significant difference in outcomes (p = 0.24) was detected between the 2 treatment groups. Complete aneurysm obliteration at 6 years was achieved in 96% (111/116) of the clipping group and in 48% (23/48) of the coiling group (p < 0.0001). In the period between the 3- and 6-year follow-ups, 3 additional patients assigned to coiling and none assigned to clipping received retreatment, for overall retreatment rates of 4.6% (13/280) for clipping and 16.4% (21/128) for coiling (p < 0.0001). When aneurysm location was considered, the 6-year results continued to match the previously reported results, with no difference in outcome for anterior circulation aneurysms at most time points. Of the anterior circulation aneurysms assigned to coiling treatment, 42% (70/168) were crossed over to clipping treatment. The outcomes for posterior circulation aneurysms continued to favor coiling. The randomization process was unexpectedly skewed, with 18 of 21 treated aneurysms of the posterior inferior cerebellar artery (PICA) being assigned to clipping, but even when PICA aneurysms were removed from the analysis, outcomes for the posterior circulation aneurysms still favored coiling. CONCLUSIONS: Although BRAT was statistically underpowered to detect small differences, these results suggest little difference in outcome between the 2 treatments for anterior circulation aneurysms. This was not the case for the posterior circulation aneurysms, where coil embolization appeared to provide a sustained advantage over clipping. Aneurysm obliteration rates in BRAT were significantly lower and retreatment rates significantly higher in the patients undergoing coiling than in those undergoing clipping. However, despite the fact that retreatment rates were higher after coiling, no recurrent hemorrhages were known to have occurred in patients undergoing coiling in BRAT who were followed up for 6 years. Sufficient questions remain about the relative benefits of the 2 treatment modalities to warrant further well-designed randomized trials.

Charcot-Marie-Tooth disease: extensive cranial nerve involvement on CT and MR imaging.

We report a case of genetically verified Charcot-Marie-Tooth disease in which the patient had cranial nerve symptoms. CT and MR imaging demonstrated enlargement of several cranial nerves, as well as their skull-base foramina, with faint contrast material enhancement identified.

Intralabyrinthine meningioma.

An 18-year-old female patient with unilateral hearing loss underwent evaluation with CT and MR imaging. A partially ossified, enhancing lesion in the bony labyrinth, with replacement of adjacent structures, was identified. Surgical biopsy revealed a meningioma arising primarily within the bony labyrinth. To our knowledge, this entity has not been previously described.

Distinction between paraclinoid and cavernous sinus aneurysms with computed tomographic angiography.

OBJECTIVE: To examine the reliability of using the optic strut as a landmark in computed tomographic (CT) angiography, to differentiate between intradural and extradural (cavernous sinus) aneurysms involving the paraclinoid segment of the internal carotid artery (ICA). METHODS: Microanatomic dissections were performed with five cadaveric heads (10 sides), to establish the relationships of the optic strut to the cavernous sinus and the ICA. Results from these anatomic studies were compared with intraoperative and CT angiographic findings for four patients with nine intracranial aneurysms involving the paraclinoid segment of the ICA. RESULTS: The inferior boundary of the optic strut accurately localized the point at which the ICA pierced the oculomotor membrane (proximal dural ring) and exited the cavernous sinus. The optic strut and its relationship to the ICA could be well observed on CT angiograms. During surgery, six of six aneurysms that arose distal to the optic strut were identified intradurally and were successfully clipped. Conversely, all aneurysms that arose proximal to the optic strut were observed to lie within the cavernous sinus. An aneurysm at the optic strut was within the clinoid segment or interdural, between the proximal and distal rings. CONCLUSION: The optic strut, as identified with CT angiography, provided a reliable anatomic landmark for accurate discrimination between intradural and extradural (cavernous sinus) aneurysms.

Vertical atlantoaxial distraction injuries: radiological criteria and clinical implications.

OBJECT: The authors sought to establish radiological criteria for the diagnosis of C1-2 vertical distraction injuries. METHODS: Conventional radiography, computerized tomography (CT), and magnetic resonance (MR) imaging findings in five patients with a C1-2 vertical distraction injury were correlated with their clinical history, operative findings, and autopsy findings. The basion-dens interval (BDI) and the C-1 and C-2 lateral mass interval (LMI) were measured in 93 control patients who underwent CT angiography; these measurements were used to define the normal BDI and LMI. The MR imaging results obtained in 30 healthy individuals were used to characterize the normal signal intensity of the C1-2 joint. The MR imaging results were compared with MR images obtained in five patients with distraction injuries. In the 93 patients, the BDI averaged 4.7 mm (standard deviation [SD] 1.7 mm, range 0.6-9 mm) and the LMI averaged 1.7 mm (SD 0.48 mm, range 0.7-3.3 mm). Based on CT scanning in the five patients with distraction injuries, the BDIs (mean 11.9 mm, SD 3.2 mm; p < 0.001) and LMIs (mean 5.5 mm, SD 2 mm; p < 0.0001) were significantly greater than in the control group. Fast-spin echo inversion-recovery MR images obtained in these five patients revealed markedly increased signal distributed throughout the C1-2 lateral mass articulations bilaterally. CONCLUSIONS: In 95% of healthy individuals, the LMI ranged between 0.7 and 2.6 mm. An LMI greater than 2.6 mm indicates the possibility of a distraction injury, which can be confirmed using MR imaging. Patients with a suspected C1-2 distraction injury may be candidates for surgical fusion of C1-2.

Posttreatment imaging of the skull base.

Imaging the skull base after surgery can be challenging because anatomic structures may have been destroyed by an underlying process or removed at surgery. Foreign substances may be introduced to fill a void left by tumor resection, for hemostasis, and to repair dural defects. Previous imaging studies must be available for comparison to understand the characteristics of an underlying lesion. By following the progression of a lesion on subsequent imaging studies, the nature of treatment-related changes and residual or recurrent pathology is best realized.

The Barrow Ruptured Aneurysm Trial: 3-year results.

OBJECT: The authors report the 3-year results of the Barrow Ruptured Aneurysm Trial (BRAT). The objective of this ongoing randomized trial is to compare the safety and efficacy of microsurgical clip occlusion and endovascular coil embolization for the treatment of acutely ruptured cerebral aneurysms and to compare functional outcomes based on clinical and angiographic data. The 1-year results have been previously reported. METHODS: Two-hundred thirty-eight patients were assigned to clip occlusion and 233 to coil embolization. There were no anatomical exclusions. Crossovers were allowed based on the treating physician's determination, but primary outcome analysis was based on the initial assignment to treatment modality. Patient outcomes were assessed independently using the modified Rankin Scale (mRS). A poor outcome was defined as an mRS score>2. At 3 years' follow-up 349 patients who had actually undergone treatment were available for evaluation. Of the 170 patients who had been originally assigned to coiling, 64 (38%) crossed over to clipping, whereas 4 (2%) of 179 patients assigned to surgery crossed over to clipping. RESULTS: The risk of a poor outcome in patients assigned to clipping compared with those assigned to coiling (35.8% vs 30%) had decreased from that observed at 1 year and was no longer significant (OR 1.30, 95% CI 0.83-2.04, p=0.25). In addition, the degree of aneurysm obliteration (p=0.0001), rate of aneurysm recurrence (p=0.01), and rate of retreatment (p=0.01) were significantly better in the group treated with clipping compared with the group treated with coiling. When outcomes were analyzed based on aneurysm location (anterior circulation, n=339; posterior circulation, n=69), there was no significant difference in the outcomes of anterior circulation aneurysms between the 2 assigned groups across time points (at discharge, 6 months, 1 year, or 3 years after treatment). The outcomes of posterior circulation aneurysms were significantly better in the coil group than in the clip group after the 1st year of follow-up, and this difference persisted after 3 years of follow-up. However, while aneurysms in the anterior circulation were well matched in their anatomical location between the 2 treatment arms, this was not the case in the posterior circulation where, for example, 18 of 21 posterior inferior cerebellar artery aneurysms were in the clip group. CONCLUSIONS: Based on mRS scores at 3 years, the outcomes of all patients assigned to coil embolization showed a favorable 5.8% absolute difference compared with outcomes of those assigned to clip occlusion, although this difference did not reach statistical significance (p=0.25). Patients in the clip group had a significantly higher degree of aneurysm obliteration and a significantly lower rate of recurrence and retreatment. In post hoc analysis examining only anterior circulation aneurysms, no outcome difference between the 2 treatment cohorts was observed at any recorded time point. CLINICAL TRIAL REGISTRATION NO.: NCT01593267 ( ClinicalTrials.gov ).

Quantitative analysis of variants of the far-lateral approach: condylar fossa and transcondylar exposures.

BACKGROUND: The rationale for choosing between the condylar fossa and transcondylar variations of the far-lateral approach requires understanding of the relationships between the occipital condyle, jugular tubercle, and hypoglossal canal. OBJECTIVE: We examined the anatomic relationship of these 3 structures and analyzed the effect that changes in these relationships have on the surgical exposure and angle of attack for these 2 approaches. METHODS: Anatomic measurements of 5 cadaveric heads from 3-dimensional computed tomographic scans were compared with direct measurements of the same specimens. The condylar fossa and transcondylar approach were performed sequentially in 8 of 10 sides. Surgical exposure and angle of attack were measured after each exposure. RESULTS: The jugular tubercle (JT) angle (JTA) measures the angle formed by reference points on the condyle, hypoglossal canal, and JT. When the JT and occipital condyle are not prominent (JTA > 180 degrees ), the transcondylar approach does not significantly increase petroclival or brainstem exposure compared with the condylar fossa approach; however, it does significantly increase the angle of attack to the junction of the posterior inferior cerebellar and vertebral arteries and the surgical angle for the medial part of the JT (P < .05). CONCLUSION: The condylar fossa and transcondylar approaches provide similar exposures of the petroclivus and brainstem when the JT and occipital condyle are not prominent (JTA > 180 degrees on 3-dimensional computed tomographic). However, for lesions below the hypoglossal canal, the transcondylar approach is preferred because it significantly increases the angle of attack.

Magnetic resonance angiographic imaging follow-up of treated intracranial aneurysms.

Conventional catheter-based angiography, magnetic resonance imaging/angiography, and computed tomographic angiography are all techniques routinely practiced for the diagnosis of aneurysms. With regard to the evaluation of treated aneurysms, each of these imaging modalities has inherent advantages and disadvantages. This review was aimed to provide a better understanding of the optimal application and interpretation of the available imaging modalities for the assessment of treated cerebral aneurysms.

Spontaneous spinal subarachnoid hemorrhage secondary to spinal aneurysms: diagnosis and treatment paradigm.

INTRODUCTION: Isolated spinal aneurysms are rare; only a few have been reported. To the best of our knowledge, this series represents the largest experience with four ruptured spinal aneurysms, all of which were treated surgically. METHODS: Clinical information from the hospital charts and diagnostic images of four patients with the diagnosis of spinal aneurysms were reviewed from the senior authors' (RFS, JMZ) office database, surgical reports, and radiological imaging database. Follow-up examinations were performed by phone interview, when possible, and by chart review. RESULTS: Between 1997 and 2004, four patients with ruptured spinal aneurysms underwent surgical treatment. All aneurysms were located within the spinal canal and manifested with spinal subarachnoid hemorrhage. No collagen disease, aortic coartaction, arteriovenous fistula, or arteriovenous malformations were identified in these patients. CONCLUSION: Subarachnoid hemorrhage within the spinal cord can be caused by ruptured aneurysms. Spinal aneurysms are rare, but should be considered within the differential diagnosis of patients with intracranial subarachnoid hemorrhage when cranial angiography is negative. Magnetic resonance imaging and selective spinal angiography are useful for workup, but definitive diagnosis may require surgical exploration.

Intra-arterial thrombolysis for acute ischemic stroke: preliminary experience with platelet glycoprotein IIb/IIIa inhibitors as adjunctive therapy.

OBJECTIVE: To evaluate the safety profile of platelet glycoprotein IIb/IIIa inhibitors administered as adjunctive therapy to patients with large-vessel occlusion and acute ischemic stroke refractory to pharmacological thrombolysis with recombinant tissue plasminogen activator (rtPA) and mechanical disruption, balloon angioplasty, or both. METHODS: Twenty-one patients (mean age, 62 yr; range, 29-88 yr) met the following criteria: 1) large-vessel occlusion and acute ischemic stroke syndrome at presentation, 2) failure to recanalize after administration of rtPA (intra-arterial and/or intravenous) with or without mechanical thrombolysis, and 3) subsequent treatment with IIb/IIIa inhibitors (intra-arterial or intravenous). RESULTS: Eleven patients had ischemia in the dominant hemisphere, 8 in the vertebrobasilar system, and 2 in the nondominant hemisphere. Twelve patients received intravenous rtPA without significant improvement; 9 patients were not candidates for intravenous rtPA. All patients received intra-arterial rtPA. The IIb/IIIa inhibitors were administered intravenously in 3 patients, intra-arterially in 16, and both intravenously and intra-arterially in 2. Balloon angioplasty was performed in 18 patients. Complete or partial recanalization was achieved in 17 of the 21 patients. After thrombolysis, 15 improved clinically. Three patients (14%) sustained an asymptomatic intracerebral hemorrhage after thrombolytic therapy. No patient was clinically worse after intervention. At last follow-up (mean, 8.5 mo), 13 patients were functionally independent (modified Rankin score, 0-3) and 8 were disabled or dead. CONCLUSION: IIb/IIIa inhibitors are an alternative for achieving recanalization. The risk of hemorrhage may be low. As part of an escalating protocol that includes pharmacological and mechanical thrombolysis, IIb/IIIa inhibitors may improve clinical outcomes.