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Intraoperative Computed Tomography for Deep Brain Stimulation Surgery: Technique and Accuracy Assessment

Neurosurgery 68[ONS Suppl 1]:ons114–ons124, 2011. DOI: 10.1227/NEU.0b013e31820781bc

The efficacy of deep brain stimulation (DBS) is highly dependent on the accuracy of lead placement.

OBJECTIVE: To describe the use of intraoperative computed tomography (iCT) to confirm lead location before surgical closure and to study the accuracy of this technique.

METHODS: Fifteen patients underwent awake microelectrode-guided DBS surgery in a stereotactic frame. A portable iCT scanner (Medtronic O-arm) was positioned around the patient’s head throughout the procedure and was used to confirm lead location before fixation of the lead to the skull. Images were computationally fused with preoperative magnetic resonance imaging (MRI), and lead tip coordinates with respect to the midpoint of the anterior commissure-posterior commissure line were measured. Tip coordinates were compared with those obtained from postoperative MRI.

RESULTS: iCT was integrated into standard frame-based microelectrode-guided DBS surgery with a minimal increase in surgical time or complexity. Technically adequate 2-dimensional and 3-dimensional images were obtained in all cases. Head positioning and fixation techniques that allow unobstructed imaging are described. Lead tip measurements on iCT fused with preoperative MRI were statistically indistinguishable from those obtained with postoperative MRI.

CONCLUSION: iCT can be easily incorporated into standard DBS surgery, replaces the need for C-arm fluoroscopy, and provides accurate intraoperative 3-dimensional confirmation of electrode tip locations relative to preoperative images and surgical plans. iCT fused to preoperative MRI may obviate the need for routine postoperative MRI in DBS surgery. Technical nuances that must be mastered for the efficient use of iCT during DBS implantation are described.

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Venous Thromboembolism Prophylaxis in Patients Undergoing Cranial Neurosurgery: A Systematic Review and Meta-analysis

Neurosurgery 68:571–581, 2011 DOI: 10.1227/NEU.0b013e3182093145

Randomized clinical trials (RCTs) have usually supported using heparin prophylaxis against venous thromboembolism (VTE) in patients undergoing cranial neurosurgery. The tradeoff between benefit and bleeding risk, however, has not been adequately characterized.

OBJECTIVE: To conduct a systematic review and meta-analysis assessing the extent to which low-dose unfractionated heparin (LDUH) or low-molecular-weight heparin (LMWH) prophylaxis reduces the rate of VTE and increases the rate of intracerebral hemorrhage (ICH) and other bleeding in patients undergoing elective cranial neurosurgery.

METHODS: We selected RCTs that evaluated LDUH or LMWH prophylaxis of VTE in patients undergoing elective cranial neurosurgery. A meta-analysis assessing heparins vs no heparin (either with or without mechanical methods) was performed.

RESULTS: Eight RCTs were identified. Six RCTs involving 1170 patients evaluated LDUH or LMWH vs a control group. Five of 6 trials found a significant reduction in the risk of symptomatic and asymptomatic VTE with heparin prophylaxis. The pooled risk ratio was 0.58 (95% confidence interval, 0.45-0.75). ICH was more common in those receiving heparin, but not statistically significantly. For every 1000 patients who receive heparin prophylaxis, 91 VTE events will be prevented (approximately 35 of which are proximal deep vein thrombosis or pulmonary embolism and 9 to 18 of which are symptomatic), whereas 7 ICHs and 28 more minor bleeds will occur.

CONCLUSION: Heparin prophylaxis for patients undergoing elective cranial neurosurgery reduces the risk of VTE but may also increase bleeding risks with a ratio of serious or symptomatic VTE relative to serious bleeding that is only slightly favorable.

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Stereotactic versus endoscopic surgery in periventricular lesions

Acta Neurochir (2011) 153:517–526.DOI 10.1007/s00701-010-0933-x

Endoscopic and stereotactic surgery have gained widespread acceptance as minimally invasive tools for the diagnosis of intracerebral pathologies. We investigated the specific advantages and disadvantages of each technique in the assessment of periventricular lesions.

Method This study included a retrospective series of 70 patients with periventricular lesions. Endoscopic surgery was performed in 17 patients (mean age, 37 years; range, 4 months–78 years) and stereotactic biopsy in 55 patients (mean age, 63 years; range, 23–80 years), including two patients who underwent both procedures.

Results Hydrocephalus was present in 13/17 patients in the endoscopic group (77%) and in 11/55 patients in the stereotactic group (20%). Diagnosis was achieved in all patients in the endoscopic group and in all but one patient in the stereotactic group, in whom histological diagnosis was obtained by endoscopic biopsy during a second operation. In the endoscopic group, additional procedures performed included ventriculostomy (2/17), cyst fenestration (3/17), endoscopic shunt revision (3/17) and placement of Rickham reservoirs or external cerebrospinal fluid drains (6/17). Adverse events occurred in one patient after endoscopy (chronic subdural hematoma) and in two patients after stereotactic surgery (one mild hemiparesis and one transitory paresis of the contralateral leg).

Conclusions Endoscopic and stereotactic surgery have distinct advantages and disadvantages in approaching periventricular lesions. The advantages of endoscopy encompass the possibility to perform additional surgical procedures during the same session (e.g. tumour reduction, third ventriculostomy, fenestration of a cyst). The visual control reduces the hazard of injury to anatomical structures and allows for a better control of bleeding although there is a considerable blind-out in such situations. The advantages of stereotactic surgery include a smaller approach and precise planning of the trajectory. It is usually performed under local anaesthesia. Both methods provide a safe and efficient therapeutic option in periventricular lesions with low surgical-related morbidity.

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Endovascular Therapy of Very Small Aneurysms of the Anterior Communicating Artery: Five-fold Increased Incidence of Rupture

Neurosurgery 68:731–737, 2011 DOI: 10.1227/NEU.0b013e3182077373

Intraprocedural rupture is a dangerous complication of endovascular treatment. Small ruptured anterior communicating artery (ACoA) aneurysms and microaneurysms present a challenge for both surgical and endovascular therapies to achieve obliteration. An understanding of the complication rates of treating ruptured ACoA microaneurysms may help guide therapeutic options.

OBJECTIVE: To report the largest cohort of ACoA microaneurysms treated with endovascular therapy over the course of the past 10 years.

METHODS: We performed a retrospective review of 347 ACoA aneurysms treated in 347 patients at Cleveland Clinic and Emory University over a 10-year period. Patient demographics, aneurysmal rupture, size, use of balloon remodeling, patient outcomes, intraprocedural rupture, and rerupture were reviewed.

RESULTS: Rupture rates were examined by size for all patients and subgroups and dichotomized to evaluate for size ranges associated with increased rupture rates. The highest risk of rupture was noted in aneurysms less than 4 mm. Of 347 aneurysms, 74 (21%) were less than 4 mm. The intraprocedural rupture rate was 5% (18/347) for ACoA aneurysms of any size. There was an intraprocedural rupture rate of 2.9% (8/273) among ACoA aneurysms greater than 4 mm compared with 13.5% (10/74) in less than 4-mm aneurysms. Procedural rupture was a statistically significant predictor of modified Rankin score after adjusting for Hunt and Hess grades (HH).

CONCLUSION: ACoA aneurysms less than 4 mm have a 5-fold higher incidence of intraprocedural rerupture during coil embolization. Outcome is negatively affected by intraprocedural rerupture after adjusting for HH grade.

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Assessment of endoscopic treatment for middle cranial fossa arachnoid cysts

Childs Nerv Syst.DOI 10.1007/s00381-011-1399-8

Endoscopic cystocisternotomy is one of three surgical methods used to treat middle cranial fossa arachnoid cysts. There is debate about which method is the best.

Objective The aim of this study is to evaluate the effectiveness and safety of endoscopic cystocisternotomy for treatment of arachnoid cysts of the middle cranial fossa.

Methods Thirty-two patients with arachnoid cysts of the middle cranial fossa who had undergone endoscopic cystocisternal fenestration between 2004 and 2009 were studied retrospectively. Data were obtained on clinical and neuroradiological presentation, indications to treat, surgical technique, complications, and the results of clinical and neuroradiological follow-up.

Results Among the 27 patients with symptoms before surgery, 8 had disappearance of symptoms and 17 had improvement of symptoms. The cyst was reduced in size or it completely disappeared in 24 (75%) patients. The incidence rate of complications was 18.8%.

Conclusions Endoscopic cystocisternal fenestration is an effective treatment for symptomatic arachnoid cysts of the middle cranial fossa and should be the initial surgical procedure.

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A Novel Method for Cerebrospinal Fluid Diversion: A Cadaveric and Animal Study

Neurosurgery 68:491–495, 2011 DOI: 10.1227/NEU.0b013e3181ffa21c

Cerebrospinal fluid (CSF) diversionary methods are fraught with complications (eg, infection, obstruction, and CSF malabsorption at the distal site).

INTRODUCTION: The authors investigated the sternum, specifically the manubrium, as a potential CSF receptacle for patients with hydrocephalus.

METHODS: Five fresh adult human cadavers had the manubrium cannulated in a suprasternal location. Tap water was infused via a metal trocar for approximately 60 minutes. Additionally, morphometric examination of the manubrium from 40 adult human skeletons was performed. Next, 4 anesthetized rhesus monkeys underwent cannulation of the manubrium: 2 were infused with 50 mL of saline over approximately 1 hour, and 2 were infused by gravity drip of saline over 24 hours. Finally, 2 adult pigs underwent long-term ventriculosternal tube placement with analysis for function and potential development of osteomyelitis.

RESULTS: Thirty liters of water were injected into all cadaveric specimens without overflow or noticeable edema. No fluid accumulation was identified. The manubrium had a mean length, width, and thickness of 5.1 cm, 5.0 cm, and 1 cm, respectively. The animals that underwent infusion of 50 mL of saline and the animals that underwent gravity drip tolerated the procedure without vital sign changes or evidence of saline leakage into the pleural cavity. The 2 pigs did not show any vital sign changes, and, 2 weeks post procedure, they had no findings of osteomyelitis.

CONCLUSION: Based on our studies, the manubrium of the sternum appears to be an ideal location for the placement of the distal end of a CSF diversionary shunt when other anatomic receptacles are not an option. In vivo human studies are now required to verify our findings.

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Advances in the Treatment and Outcome of Brainstem Cavernous Malformation Surgery: A Single-Center Case Series of 300 Surgically Treated Patients

Neurosurgery 68:403–415, 2011 DOI: 10.1227/NEU.0b013e3181ff9cde

Brainstem cavernous malformations (BSCMs) are relatively uncommon, low-flow vascular lesions. Because of their relative rarity, relatively little data on their natural history and on the efficacy and durability of their treatment.

OBJECTIVE: To evaluate the long-term durability of surgical treatment of BSCMs and to document patient outcomes and clinical complications.

METHODS: The charts of all patients undergoing surgical treatment of BSCM between 1985 and 2009 were reviewed retrospectively. The study population consisted of 300 patients who had surgery for BSCM. Forty patients were under 19 years of age at surgery; pediatric BSCMs have been reported separately. Patient demographics, lesion characteristics, surgical approaches, and patient outcomes were examined.

RESULTS: The study population consisted of 260 adult patients with a female-to-male ratio of 1.5 and mean age of 41.8 years. Of the 260 patients, 252 presented with a clinical or radiographic history of hemorrhage. The mean follow-up in 240 patients was 51 months. The mean Glasgow Outcome Scale on admission, at discharge, and at last follow-up was 4.4, 4.2, and 4.6. Postoperatively, 137 patients (53%) developed new or worsening neurological symptoms. Permanent new deficits remained in 93 patients 3(36%). There were perioperative complications in 74 patients (28%); tracheostomy, feeding tube placement, and cerebrospinal fluid leakage were most common. Eighteen patients (6.9%) experienced 20 rehemorrhages. Twelve patients required reoperation for residual/recurrent BSCM. The overall annual risk of postoperative rehemorrhage was 2%/patient.

CONCLUSION: Although BSCM surgery has significant associated risks, including perioperative complications, new neurological deficits, and death, most patients have favorable outcomes. Overall, surgery markedly improved the risk of rehemorrhage and related symptoms and should be considered in patients with accessible lesions.

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Minimally invasive extracavitary approach for thoracic discectomy and interbody fusion: 1-year clinical and radiographic outcomes in 13 patients compared with a cohort of traditional anterior transthoracic approaches

J Neurosurg Spine 14:250–260, 2011.DOI: 10.3171/2010.10.SPINE09456

Open transthoracic approaches, considered the standard in treating thoracic disc herniation (TDH), are associated with significant comorbidities. The authors describe a minimally invasive lateral extracavitary tubular approach for discectomy and fusion (MIECTDF) to treat TDH.

Methods. In 13 patients (5 men, 8 women; mean age 51.8 years) with myelopathy and 15 noncalcified TDHs, the authors achieved a far-lateral trajectory by dilating percutaneously to a 20-mm working portal docked at the transverse process–facet junction, which then provided a corridor for a near-total discectomy, bilateral laminotomies, and interbody arthrodesis requiring minimal cord retraction. A cohort of 11 demographically comparable patients treated via transthoracic approaches was used as control.

Results. Preoperative Frankel grades were B in 1 patient, C in 4, D in 5, and E in 3, whereas at mean of 10 months, 11 had Grade E function and 2 had Grade D function. Mean surgical metrics were operating room time 93.75 minutes, blood loss 33 ml, and hospital stay 3.1 days. Complications included 4 transient paresthesias, 1 CSF leak, 1 abdominal wall weakness, and 3 nonwound infections. One-year follow-up MR imaging revealed full decompression in all cases and no cage migration. Mean visual analog scales scores preoperative, at 6 weeks, 3 months, and 1 year were 5.6, 4.5, 3.2, and 1.2, respectively. No differences existed in preoperative clinical and radiographic profile of the study and control groups. Compared with controls, the MIECTDF group achieved superior scores in all metrics (p < 0.01) except for equivalent 1-year neurological outcomes.

Conclusions. Compared with transthoracic procedures, MIECTDF effectively decompressed the spinal canal, yielding identical 1-year radiographic and clinical outcomes to those seen in controls, while producing superior clinical scores in the interim. Thus, MIECTDF is the authors’ treatment of choice for TDH.

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Variability among pediatric neurosurgeons in the threshold for ventricular shunting in asymptomatic children with hydrocephalus

J Neurosurg Pediatrics 7:000–000, 2011.DOI: 10.3171/2010.11.PEDS10275

The thresholds for shunting CSF in children with asymptomatic hydrocephalus are unclear; there are neither guidelines nor sufficient research to determine what degree of hydrocephalus should be treated. The authors hypothesize that 1) pediatric neurosurgeons currently have high thresholds for recommending treatment for these children, but 2) there is significant variability among these treatment thresholds.

Methods. The authors surveyed attendees of the Joint Pediatric Neurosurgery Section meeting in Spokane, Washington, in December 2008, regarding their treatment thresholds for 22 clinical scenarios. Each participant was provided an illustration of 5 imaging studies (3 slices each) showing progressively larger ventricles. For each scenario, respondents were asked to indicate the minimum ventricular size they would treat, if any. Responses were quantified from 1 to 6 from smaller to larger, with 6 being no treatment, and a mean theoretical treated ventricular size (MTTVS) was calculated for each scenario.

Results. Respondents were relatively conservative in recommending treatment, with MTTVSs of 3.7–6.0; in 13 scenarios, the MTTVS was greater than 5.0 (larger than the largest presented ventricular size). For scenarios in which a mean frontooccipital ratio could be calculated, the value ranged from 0.55 to 0.67 (moderate to severe hydrocephalus). Although there were clear majority responses for each scenario, there was also significant variability. There were no patterns of association with the respondent’s age, training, board certification, or type or location of practice.

Conclusions. This study demonstrates that pediatric neurosurgeons’ thresholds for treating asymptomatic children with hydrocephalus are generally high, but there is also significant variability.

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Hemangiopericytomas grade II are not benign tumors

Acta Neurochir (2011) 153:385–394.DOI 10.1007/s00701-010-0877-1

Hemangiopericytomas (HPs) of the central nervous system are rare tumors and afflicted with a high propensity of recurrences and metastases. Histopathologically, HPs correspond to differentiated (WHO grade II) and anaplastic (WHO grade III) tumors. With respect to the available literature and our own experiences, the aggressiveness, especially of differentiated grade II HPs, seems to be underestimated. Methods Thus, in this retrospective study, we describe tumor behavior and examined the effect of radio- and chemotherapy on tumor control with respect to the WHO classification of grade II and III neoplasms. This study consists of 15 patients with cerebral (n=10) and spinal (n=5) HPs. Results Seven HPs were histopathologically classified as grade II and eight as anaplastic grade III tumors. Complete surgical resection could be achieved in 60% of cerebral and in 25% of spinal HPs. In total, local recurrences occurred in 20% of patients within 17.3 months after the primary operation. Recurrences occurred both from differentiated (n=1) and anaplastic (n=2) neoplasms. Treatment comprised re-operation followed by radio- and chemotherapy. Pointing out the importance of the extent of surgical resection, in this study, we could not detect a single patient showing any recurrences or systemic metastases after complete surgical resection of grade II HPs. During primary diagnostics, four patients showed systemic metastases. Although these tumors could be controlled via surgery, systemic metastases appeared in further four patients within 60.4 months. Interestingly, two of them were classified as differentiated tumors (WHO grade II). To control tumor progress, radiotherapy seemed to be partially effective. On the other hand, however, chemotherapy did not show any effect on tumor control. With respect to these results, screening investigations seem to be indispensable and are highly recommended during primary diagnostics and after the appearance of recurrences or metastases, independent of the histopathological staging of the tumor. Conclusion With respect to our results, radical surgical resection offers the best treatment option to control tumor progress. In case of subtotal resection or histopathologically diagnosed anaplasia (WHO III), radiotherapy seems to be indicated; however, chemotherapy did not show effectiveness to control tumor progress.

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Utility of Ictal Single Photon Emission Computed Tomography in Mesial Temporal Lobe Epilepsy With Hippocampal Atrophy: A Randomized Trial

Neurosurgery 68:431–436, 2011 DOI: 10.1227/NEU.0b013e318201c293

The development of newer diagnostic technologies has reduced the need for invasive electroencephalographic (EEG) studies in identifying the epileptogenic zone, especially in adult patients with mesial temporal lobe epilepsy and hippocampal sclerosis (MTLE-HS).

OBJECTIVE: To evaluate ictal single photon emission computed tomography (SPECT) in the evaluation and treatment of patients with MTLE-HS.

METHODS: MTLE patients were randomly assigned to those with (SPECT, n = 124) and without ictal SPECT (non-SPECT, n = 116) in an intent-to-treat protocol. Primary end points were the proportion of patients with invasive EEG studies, and those offered surgery. Secondary end points were the length of hospital stay and the proportion of patients with secondarily generalized seizures (SGS) during video-EEG, postsurgical seizure outcome, and hospital cost.

RESULTS: The proportion of patients offered surgery was similar in the SPECT (85%) and non-SPECT groups (81%), as well as the proportion that had invasive EEG studies (27% vs 23%). The mean duration of hospital stay was 1 day longer for the SPECT group (P , 0.001). SGS occurred in 51% of the SPECT and 26% of the non-SPECT group (P , 0.001). The cost of the presurgical evaluation was 35% higher for the SPECT compared with the non-SPECT group (P , 0.001). The proportion of patients seizure-free after surgery was similar in the SPECT (59%) compared with non-SPECT group (54%).

CONCLUSION: Ictal-SPECT did not add localizing value beyond what was provided by EEG-video telemetry and structural MRI that altered the surgical decision and outcome for MTLE-HS patients. Ictal-SPECT increased hospital stay was associated with increased costs and a higher chance of SGS during video-EEG monitoring. These findings support the notion that a protocol including ictal SPECT is equivalent to one without SPECT in the presurgical evaluation of adult patients with MTLE-HS.

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Risk of Hemorrhage in Patients With Untreated Spetzler-Martin Grade IV and V Arteriovenous Malformations: A Long-term Follow-up Study in 63 Patients

Neurosurgery 68:372–378, 2011 DOI: 10.1227/NEU.0b013e3181ffe931

Treatment of Spetzler-Martin Grade IV and V brain arteriovenous malformations (ie, high-grade AVMs) carries a high risk of morbidity and even mortality. However, little is known about the behavior of these lesions if left untreated.

OBJECTIVE: To investigate the natural history of patients with high-grade AVMs.

METHODS: Patients with untreated high-grade AVMs admitted to our center between 1952 and 2005 were followed from admission until death, AVM rupture, or initiation of treatment. Rates of rupture and various risk factors were analyzed using Kaplan-Meier life table analyses and Cox proportional hazards models. Functional outcome was assessed 1 year after possible AVM rupture using the Glasgow Outcome Scale.

RESULTS: Sixty-three patients with a mean follow-up time of 11.0 years (range, 1 month to 39.6 years) were identified. Twenty-three patients (37%) experienced a subsequent rupture. The average annual rate of rupture was 3.3%. In patients with hemorrhagic presentation, the annual rate was 6.0%, compared to 1.1% in patients with unruptured AVMs (P = .001, log-rank test; hazard ratio, 5.09 [1.40-18.5, 95% CI]; P = .013, multivariate Cox regression model). One year after the first subsequent rupture, 6 patients (26%) had died, and 9 (39%) had moderate or severe disability.

CONCLUSION: Untreated high grade AVMs presenting with hemorrhage have a significant risk of subsequent rupture, and their rupture carries a higher risk of case fatality and permanent morbidity than AVMs in general. The risks associated with their treatment should be appraised in light of perilous natural history.

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Molecular biology of familial and sporadic vestibular schwannomas: implications for novel therapeutics

J Neurosurg 114:359–366, 2011.DOI: 10.3171/2009.10.JNS091135

Vestibular schwannomas (VSs) are benign tumors arising from the sheath of cranial nerve VIII. The pathogenesis underlying most familial and sporadic VSs has been linked to a mutation in a single gene, the neurofibromin 2 (NF2) gene located on chromosome 22, band q11–13.1.

In this review, the authors summarized what is known about the epidemiology of NF2 mutations and patients with VSs. The authors also discuss the function of the NF2 gene product, merlin, and describe the known and hypothetical effects of genetic mutations that lead to merlin dysfunction on a broad variety of cellular and histological end points.

A better understanding of the molecular pathobiology of VSs may lead to novel therapeutics to augment current modalities of treatment while minimizing morbidity.

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Atypical pituitary adenomas: incidence, clinical characteristics, and implications

J Neurosurg 114:336–344, 2011.DOI: 10.3171/2010.8.JNS10290

The 2004 WHO classification of pituitary adenomas now includes an “atypical” variant, defined as follows: MIB-1 proliferative index greater than 3%, excessive p53 immunoreactivity, and increased mitotic activity. The authors review the incidence of this atypical histopathological subtype and its correlation with tumor subtype, invasion, and surgical features.

Methods. The records of 121 consecutive patients who underwent transsphenoidal surgery for pituitary adenomas during an 18-month period were retrospectively reviewed for evidence of atypical adenomas.

Results. Eighteen adenomas (15%) met the criteria for atypical lesions; 17 (94%) of the 18 were macroadenomas. On imaging, 15 (83%) demonstrated imaging evidence of surrounding invasion, compared with 45% of typical adenomas (p = 0.004). Atypical tumors occurred in 12 female (67%) and 6 male (33%) patients. Patient age ranged from 16 to 70 years (mean 48 years). Nine patients (50%) had hormonally active tumors, and 9 had nonfunctional lesions. Four (22%) of the 18 patients presented to us with recurrent tumors. Immunohistochemical analysis demonstrated the following tumor subtypes: GH-secreting adenoma with plurihormonal staining (5 patients [28%]); null-cell adenoma (5 patients [28%]); silent ACTH tumor (3 patients [17%]), ACTH-staining tumor with Cushing’s disease (2 patients [11%]), prolactinoma (2 patients [11%]), and silent FSH-staining tumor (1 patient [6%]). The MIB-1 labeling index ranged from 3% to 20% (mean 7%).

Conclusions. Atypical tumors were identified in 15% of resected pituitary adenomas, and they tended to be aggressive, invasive macroadenomas. More longitudinal follow-up is required to determine whether surgical outcomes, potential for recurrence, or metastasis of atypical adenomas vary significantly from their typical counterparts.

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Surgical approaches to hypothalamic hamartomas

Neurosurg Focus 30 (2):E2, 2011.(DOI: 10.3171/2010.11.FOCUS10250)

Hypothalamic hamartomas (HHs) are devastating lesions causing refractory epilepsy, rage attacks, social ineptitude, and precocious puberty. Microsurgical and/or endoscopic resection offers an excellent risk/benefit profile for cure or improvement of epilepsy.

Methods. The authors reviewed a prospective database maintained during the first 7 years of the Barrow Hypothalamic Hamartoma program. They describe and illustrate their surgical methods, and they review data from several previous publications regarding surgical outcome.

Results. To date, the authors have performed surgery in 165 patients for symptomatic HHs. Patients underwent an endoscopic, transcallosal, or skull base approach, or multiple approaches. Twenty-six patients (15.8%) required more than 1 treatment for their HH.

Conclusions. Microsurgical and endoscopic resection of symptomatic HHs are technically demanding but can be performed safely with excellent results and an acceptable risk profile. Meticulous attention to the subtleties of surgical management helps optimize outcomes.

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Cervical Facet Degeneration After Total Disc Replacement: 280 Levels in 162 Patients: 5-Year Follow-up

Neurosurg Q 2011;21:17–21.

Much information and classifications of lumbar facet joint degeneration after lumbar total disc replacement are available, but nowadays in the cervical spine this concept is unstudied.

Analyzing our experience, we propose a computed tomography (CT) scan classification to evaluate degenerative facet joint disease after cervical arthroplasty. After 5-year follow-up for total disc replacement in a consecutive series of 162 patients (44.5±8.6-y-old) with a total of 280 Porous Coated Motion total cervical disc replacement from C3-4 to C7-T1, we analyzed the facet degeneration in 4 grades using CT scan, and compared with preoperative images. CT scans, x-rays, and clinical outcomes were collected preoperatively and postoperatively after 3 and 6 months, and annually after 12-month follow-up. The Neck Disability Index and Visual Analog Scale were used to assess pain and functional outcomes.

From all operated levels, we found 8.57% (24 levels) of degenerated facets. On the basis of the proposed classification, 50% (12 levels) of all degenerated levels had grade I, 37.5% (9 levels) with grade II, 8.3% (2 levels) with grade III, and 4.16% (1 level) had grade IV of facet degeneration. In patients with grades III and IV, it was possible to observe a worsening in Visual Analog Scale outcome assessment.

Facet joint degeneration is a possible consequence of cervical disc arthroplasty, despite its low rate occurrence. We did not find relationship between the early grades of CT observed facet degeneration and clinical results, but in grades III and IV there was correlation. A CT scan classification to evaluate cervical degenerative facet joint disease is essential to better understand and report this spinal phenomenon.

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Artificial total disc replacement versus fusion for the cervical spine: a systematic review

Eur Spine J (2011) 20:177–184. DOI 10.1007/s00586-010-1583-7

Cervical total disc replacement (CTDR) has been increasingly used as an alternative to fusion surgery in patients with pain or neurological symptoms in the cervical spine who do not respond to non-surgical treatment.

A systematic literature review has been conducted to evaluate whether CTDR is more efficacious and safer than fusion or non-surgical treatment. Published evidence up to date is summarised qualitatively according to the GRADE methodology.

After 2 years of follow-up, studies demonstrated statistically significant non-inferiority of CTDR versus fusion with respect to the composite outcome ‘overall success’. Single patient relevant endpoints such as pain, disability or quality of life improved in both groups with no superiority of CTDR. Both technologies showed similar complication rates. No evidence is available for the comparison between CTDR and non-surgical treatment. In the long run improvement of health outcomes seems to be similar in CTDR and fusion, however, the study quality is often severely limited. After both interventions, many patients still face problems. A difficulty per se is the correct diagnosis and indication for surgical interventions in the cervical spine. CTDR is no better than fusion in alleviating symptoms related to disc degeneration in the cervical spine. In the context of limited resources, a net cost comparison may be sensible.

So far, CTDR is not recommended for routine use. As many trials are ongoing, reevaluation at a later date will be required. Future research needs to address the relative effectiveness between CTDR and conservative treatment.

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Aneurysm Volume-to-Ostium Area Ratio: A Parameter Useful for Discriminating the Rupture Status of Intracranial Aneurysms

Neurosurgery 68:310–318, 2011 DOI: 10.1227/NEU.0b013e3182010ed0

Slow or stagnant flow is a hemodynamic feature that has been linked to the risk of aneurysm rupture.

OBJECTIVE: To assess the potential value of the ratio of the volume of an aneurysm to the area of its ostium (VOR) as an indicator of intra-aneurysmal slow flow and, thus, in turn, the risk of rupture.

METHODS: Using a sample defined from internal databases, a retrospective analysis of aneurysm size, aspect ratio (AR), and VOR was performed on a series of 155 consecutive aneurysms having undergone 3-dimensional digital subtraction angiography as a part of their evaluation. Measurements were obtained from 3-dimensional digital subtraction angiography studies using commercial software. Aneurysm size, AR, and VOR were correlated with rupture status (ruptured or unruptured). A multiple logistic regression model that best correlated with rupture status was generated to evaluate which of these parameters was the most useful to discriminate rupture status. This model was validated using an independent database of 62 consecutive aneurysms acquired outside the retrospective study interval.

RESULTS: VOR showed better discrimination for rupture status than did size and AR. The best logistic regression model, which included VOR rather than size or AR, determined rupture status correctly in 80.6% of subjects. The reproducibility calculating AR and VOR was excellent.

CONCLUSION: Determination of VOR was easily done and reproducible using widely available commercial equipment. It may be a more robust parameter to discriminate rupture status than AR.

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Endocrinologic, neurologic, and visual morbidity after treatment for craniopharyngioma

J Neurooncol (2011) 101:463–476. DOI 10.1007/s11060-010-0265-y

Craniopharyngiomas are locally aggressive tumors which typically are focused in the sellar and suprasellar region near a number of critical neural and vascular structures mediating endocrinologic, behavioral, and visual functions. The present study aims to summarize and compare the published literature regarding morbidity resulting from treatment of craniopharyngioma.

We performed a comprehensive search of the published English language literature to identify studies publishing outcome data of patients undergoing surgery for craniopharyngioma. Comparisons of the rates of endocrine, vascular, neurological, and visual complications were performed using Pearson’s chi-squared test, and covariates of interest were fitted into a multivariate logistic regression model.

In our data set, 540 patients underwent surgical resection of their tumor. 138 patients received biopsy alone followed by some form of radiotherapy. Mean overall follow-up for all patients in these studies was 54 ± 1.8 months. The overall rate of new endocrinopathy for all patients undergoing surgical resection of their mass was 37% (95% CI = 33– 41). Patients receiving GTR had over 2.5 times the rate of developing at least one endocrinopathy compared to patients receiving STR alone or STR + XRT (52 vs. 19 vs. 20%, v2 P<0.00001). On multivariate analysis, GTR conferred a significant increase in the risk of endocrinopathy compared to STR + XRT (OR = 3.45, 95% CI = 2.05–5.81, P<0.00001), after controlling for study size and the presence of significant hypothalamic involvement. There was a statistical trend towards worse visual outcomes in patients receiving XRT after STR compared to GTR or STR alone (GTR = 3.5% vs. STR 2.1% vs. STR + XRT 6.4%, P = 0.11). Given the difficulty in obtaining class 1 data regarding the treatment of this tumor, this study can serve as an estimate of expected outcomes for these patients, and guide decision making until these data are available.

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Categorization and characterization of lesions of the orbital apex

Neuroradiology (2011) 53:89–107. DOI 10.1007/s00234-010-0712-7

The apex of the orbit is formed by the union of the lesser and greater wings of the sphenoid bone and acts as an osseous tunnel for numerous neurovascular structures entering the orbit from the cranial vault. Lesions of the orbital apex are clinically important as they can have an adverse effect on vision. A broad range of lesions can occur here, and our purpose is to organize the pathologic processes which occur in the orbital apex into logical imaging differentials, establish an organized approach to image analysis, and present examples of representative lesions.

Methods We review the anatomy of the orbital apex and categorize and describe the pathologic entities that are encountered most frequently in this anatomically compact region and identify imaging patterns that can help to narrow the differential diagnosis.

Results Categories of orbital apex lesions include neoplasms, inflammatory processes, infections, lesions causing extrinsic compression, and vascular lesions. This categorization provides an organized framework to facilitate a reasonable differential diagnosis. Computed tomography and magnetic resonance imaging are the modalities of choice to evaluate and characterize orbital apex lesions, and imaging examples utilizing these modalities will be presented.

Conclusion The orbital apex is a clinically important anatomical region and hosts diverse pathologic processes. An awareness of common imaging patterns can help to generate a focused differential diagnosis. A systematic categorical approach can be of help to radiologists attempting to accurately characterize lesions in this area.

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