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Awake craniotomy in intraoperative MRI

Awake craniotomy for gliomas in a high-field intraoperative magnetic resonance imaging suite

J Neurosurg 121:810–817, 2014

The object of this study was to describe the experience of combining awake craniotomy techniques with high-field (1.5 T) intraoperative MRI (iMRI) for tumors adjacent to eloquent cortex.

Methods. From a prospective database the authors obtained and evaluated the records of all patients who had undergone awake craniotomy procedures with cortical and subcortical mapping in the iMRI suite. The integration of these two modalities was assessed with respect to safety, operative times, workflow, extent of resection (EOR), and neurological outcome.

Results. Between February 2010 and December 2011, 42 awake craniotomy procedures using iMRI were performed in 41 patients for the removal of intraaxial tumors. There were 31 left-sided and 11 right-sided tumors. In half of the cases (21 [50%] of 42), the patient was kept awake for both motor and speech mapping. The mean duration of surgery overall was 7.3 hours (range 4.0–13.9 hours). The median EOR overall was 90%, and gross-total resection (EOR ≥ 95%) was achieved in 17 cases (40.5%). After viewing the first MR images after initial resection, further resection was performed in 17 cases (40.5%); the mean EOR in these cases increased from 56% to 67% after further resection. No deficits were observed preoperatively in 33 cases (78.5%), and worsening neurological deficits were noted immediately after surgery in 11 cases (26.2%). At 1 month after surgery, however, worsened neurological function was observed in only 1 case (2.3%).

Conclusions. There was a learning curve with regard to patient positioning and setup times, although it did not adversely affect patient outcomes. Awake craniotomy can be safely performed in a high-field (1.5 T) iMRI suite to maximize tumor resection in eloquent brain areas with an acceptable morbidity profile at 1 month.

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Cervical Spondylotic Myelopathy Surgical Trial: Randomized, Controlled Trial Design and Rationale

Cervical Spondylotic Myelopathy Surgical Trial- Randomized, Controlled Trial Design and Rationale

Neurosurgery 75:334–346, 2014

Cervical spondylotic myelopathy (CSM) is the most common cause of spinal cord dysfunction in the world. There are significant practice variation and uncertainty as to the optimal surgical approach for treating CSM.

OBJECTIVE: To determine whether ventral surgery is associated with superior Short Form- 36 Physical Component Summary outcome at the 1-year follow-up compared with dorsal (laminectomy/fusion or laminoplasty) surgery for the treatment of CSM, to investigate whether postoperative sagittal balance is an independent predictor of overall outcome, and to compare health resource use for ventral and dorsal procedures.

METHODS: The study is a randomized, controlled trial with a nonrandomized arm for patients who are eligible but decline randomization. Two hundred fifty patients (159 randomized) with CSM from 11 sites will be recruited over 18 months. The primary outcome is the Short Form-36 Physical Component Summary score. Secondary outcomes include disease-specific outcomes, overall health-related quality of life (EuroQOL 5-dimension questionnaire), and health resource use.

EXPECTED OUTCOMES: This will be the first randomized, controlled trial to compare directly the health-related quality-of-life outcomes for ventral vs dorsal surgery for treating CSM.

DISCUSSION: A National Institutes of Health-funded (1R13AR065834-01) investigator meeting was held before the initiation of the trial to bring multiple stakeholders together to finalize the study protocol. Study investigators, coordinators, and major stakeholders were able to attend and discuss strengths of, limitations of, and concerns about the study. The final protocol was approved for funding by the Patient-Centered Outcomes Research Institute (CE-1304-6173). The trial began enrollment on April 1, 2014.

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Endoscopic endonasal surgery for olfactory groove meningiomas: outcomes and limitations in 50 patients

Endoscopic endonasal surgery for olfactory groove meningiomas- outcomes and limitations in 50 patients

Neurosurg Focus 37 (4):E8, 2014

Recently, endoscopic endonasal surgery (EES) has been introduced in the management of skull base tumors, with constantly improving outcomes and increasing indications. The authors retrospectively reviewed the effectiveness of EES in the management of olfactory groove meningiomas.

Methods. Between February 2003 and December 2012, 50 patients (64% female) with olfactory groove meningiomas underwent EES at the University of Pittsburgh Medical Center. The authors present the results of EES and analyze the resection rates, clinical outcome, complications, and limitations of this approach.

Results. Forty-four patients presented with primary tumors, whereas six were previously treated elsewhere. The patients’ mean age was 57.1 years (range 27–88 years). Clinical presentation included altered mental status (36%), visual loss (30%), headache (24%), and seizures (20%). The mean maximum tumor diameter was 41.6 mm (range 18–80 mm). All patients underwent EES, which was performed in stages in 18 giant tumors. Complete tumor resection (Simpson Grade I) was achieved in 66.7% of the 45 patients in whom it was the goal, and 13 (28.9%) had neartotal resection (> 95% of the tumor). Tumor size, calcification, and absence of cortical cuff from vasculature were significant factors that influenced the degree of resection (p = 0.002, p = 0.024, and p = 0.028, respectively). Tumor residual was usually at the most lateral and anterior tumor margins. Following EES, mental status was improved or normalized in 77.8% of the cases, vision was improved or restored in 86.7%, and headaches resolved in 83.3%. There was no postoperative deterioration of presenting symptoms. Complications were increased in tumors > 40 mm and included CSF leakage (30%), which was significantly associated with lobular tumor configuration (p = 0.048); pulmonary embolism/deep vein thrombosis, more commonly in elderly patients (20%); sinus infections (10%); and delayed abscess months or years after EES (6%). One patient had an intraoperative vascular injury resulting in transient hemiparesis (2%). There were no perioperative deaths. During a mean follow-up period of 32 months (median 22 months, range 1–115 months), 1 patient underwent repeat EES for tumor regrowth.

Conclusions. Endoscopic endonasal surgery has shown good clinical outcomes regardless of patient age, previous treatment, or tumor characteristics. Tumor size > 40 mm, calcification, and absence of cortical vascular cuff limit GTR with EES; in addition, large tumors are associated with increased postoperative complications. Significant lateral and anterior dural involvement may represent indications for using traditional craniotomies for the management of these tumors. Postoperative CSF leakage remains a problem that necessitates innovations in EES reconstruction techniques.

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Successful treatment of multiple intracranial meningiomas with the antiprogesterone receptor agent mifepristone (RU486)

RU486

Acta Neurochir (2014) 156:1831–1835

Meningiomas are the most frequent primary brain tumor in adults. Evidence suggests that female sex hormones play a role in the meningioma tumorigenesis. In particular, progesterone, has a receptor (PR) that is highly expressed in the majority of grade I meningiomas. Multiple meningiomas (diffuse meningiomatosis) are less frequent, but have a higher female predominance and a higher PR expression. They are, therefore, attractive candidates for anti-PR therapy.

Methods We treated three consecutive women with multiple meningiomas with mifepristone (RU 486). It is a synthetic steroid with high affinity for both progesterone and glucocorticoid receptors. Results The treatment was well tolerated, and we observed an important and long-lasting clinical (3/3) and radiological response (2/3) or stabilisation. All the three patients are now stable after five to nine years of treatment.

Conclusions These encouraging results strongly support a prospective clinical trial in this preselected population.

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Management of perisylvian arteriovenous malformations

Management of perisylvian arteriovenous malformations

Neurosurg Focus 37 (3):E13, 2014

Sylvian arteriovenous malformations (sAVMs) are challenging lesions of the central nervous system. The natural history of these unique lesions as well as clinical outcomes following treatment of sAVMs has been limited to case series owing to the rarity of these lesions. The authors present their experience with sAVMs and review the literature.

Methods. In accordance with the Henry Ford Institutional Review Board, medical records of patients with sAVMs treated from 2000 to 2012 were reviewed. Clinical data were retrospectively collected to calculate pre- and posttreatment modified Rankin Scale scores for all patients.

Results. The authors identified 15 patients with sAVMs who received treatment. Of these, 12 were female and 3 were male, and the average age at presentation was 39.6 ± 12.94 years (± SD). Two patients (13.3%) had Spetzler- Martin Grade I lesions, 6 patients (40%) had Grade II lesions, 5 patients (33.3%) had Grade III lesions, and another 2 (13.3%) harbored Grade IV arteriovenous malformations (AVMs). According to the Sugita classification, 6 patients (40%) had medial lesions, 6 (40%) had lateral lesions, 2 (13.3%) had deep lesions, and 1 patient (6.67%) had a pure sAVM. Eight patients (53.3%) underwent stereotactic radiosurgery while 7 patients (46.7%) had microsurgical resection; 1 patient underwent surgical extirpation after incomplete response following radiosurgery. After treatment, 9 patients were unchanged from pretreatment (60%), 3 patients worsened, and 2 patients had improved functional outcome (20% and 13.3%, respectively). The authors’ literature search yielded 348 patients with sAVMs, most of them harboring Spetzler-Martin Grade II and III lesions. Approximately 98% of the patients underwent resection with excellent outcomes.

Conclusions. While the ideal choice of therapeutic modality for cerebral AVMs remains controversial in light of the recent publication of the ARUBA (A Randomized trial of Unruptured Brain AVMs) trial, a multidisciplinary treatment approach for the management of sAVMs can lead to acceptable neurological outcome.

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A Novel Single Twist-Drill Access Device for Multimodal Intracranial Monitoring

A Novel Single Twist-Drill Access Device

Operative Neurosurgery 10:400–411, 2014

Multimodal intracranial monitoring in the neurosurgical patient requires insertion of probes through multiple craniostomies.

OBJECTIVE: To report our 5-year experience with a novel device allowing multimodal monitoring though a single twist-drill hole.

METHODS: All devices (Hummingbird Synergy, Innerspace) were placed at the Kocher point between 2008 and 2013 at our institution. An independent clinical research nurse prospectively collected data on all bedside placements. Placement accuracy was graded on computed tomography scan as grade 1 (ipsilateral frontal horn or third ventricle), grade 2 (contralateral lateral ventricle), and grade 3 (anywhere else). Infection was monitored with serial cerebrospinal fluid samples.

RESULTS: Two hundred seventy-five devices (198 at bedside, 77 in operating room) were placed in patients with spontaneous subarachnoid hemorrhage (49%), traumatic brain injury (47%), and others (4%) for a median duration of 6 days. A junior (postgraduate year 1-2), midlevel (postgraduate year 3-4), or senior resident (postgraduate year 5-6) placed 39%, 32%, and 29% of the devices, respectively. Ninety-two percent of all devices placed were draining cerebrospinal fluid, ie, were grade 1 (75%) or 2 (17%). Placement accuracy did not vary with level of training. Complications included hemorrhage (10%) and infection (4%), with 1 patient requiring intraparenchymal hematoma evacuation and a second requiring abscess drainage. These rates were lower than reported in the literature for standard external ventricular drains.

CONCLUSION: Hummingbird Synergy is a novel single-port access device for multimodal intracranial monitoring that can be placed safely at the bedside or in the operating room with placement accuracy and has a complication profile similar to or better than that for standard external ventricular drains.

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Three-Dimensional Reconstruction of the Topographical Cerebral Surface Anatomy for Presurgical Planning With Free OsiriX Software

Three-Dimensional Reconstruction of the Topographical Cerebral Surface Anatomy for Presurgical Planning With Free OsiriX Software

Neurosurgery 10:426–435, 2014

During surgery for intrinsic brain lesions, it is important to distinguish the pathological gyrus from the surrounding normal sulci and gyri. This task is usually tedious because of the pia-arachnoid membranes with their arterial and venous complexes that obscure the underlying anatomy. Moreover, most tumors grow in the white matter without initially distorting the cortical anatomy, making their direct visualization more difficult.

OBJECTIVE: To create and evaluate a simple and free surgical planning tool to simulate the anatomy of the surgical field with and without vessels.

METHODS: We used free computer software (OsiriX Medical Imaging Software) that allowed us to create 3-dimensional reconstructions of the cerebral surface with and without cortical vessels. These reconstructions made use of magnetic resonance images from 51 patients with neocortical supratentorial lesions operated on over a period of 21 months (June 2011 to February 2013). The 3-dimensional (3-D) anatomic images were compared with the true surgical view to evaluate their accuracy. In all patients, the landmarks determined by 3-D reconstruction were cross-checked during surgery with high-resolution ultrasonography; in select cases, they were also checked with indocyanine green videoangiography.

RESULTS: The reconstructed neurovascular structures were confirmed intraoperatively in all patients. We found this technique to be extremely useful in achieving pure lesionectomy, as it defines tumor’s borders precisely.

CONCLUSION: A 3-D reconstruction of the cortical surface can be easily created with free OsiriX software. This technique helps the surgeon perfect the mentally created 3-D picture of the tumor location to carry out cleaner, safer surgeries.

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Vertebral endplate change as a feature of intervertebral disc degeneration: a heritability study

Vertebral endplate change as a feature of intervertebral disc degeneration- a heritability study

Eur Spine J (2014) 23:1856–1862

Purpose: To study the prevalence of vertebral endplate or Modic change (MC), the progression of MC over a 10-year follow-up and the heritability of MC prevalence in a classical twin study.

Methods: The study population was recruited from TwinsUK register between 1996 and 2000. MC was evaluated from T2-weighted lumbar magnetic resonance imaging (MRI) at baseline and follow-up. Heritability was estimated using variance components analysis. Baseline MRI with appropriate data was available for 831 twins and follow-up for 436 twins. In total, both baseline and followup imaging were available for 347 twins.

Results: Mean age of the study population was 54.1 years (range 45.7–62.5) and females comprised 96 %. The prevalence of MC at baseline was 32.1 % and at follow-up 48.4 %. The incidence of MC during the 10-year follow-up was 21.6 % and was highest at L4–5 and L5–S1. MC regressed totally in 3.5 % of twins. Twins with prevalent MC at baseline demonstrated a higher incidence of MC at upper lumbar levels during follow-up compared to twins without baseline MC (p = 0.009). Probandwise concordance rates were higher in monozygotic (0.56) than dizygotic twin pairs (0.39) suggestive of familial influence. Heritability of MC prevalence was estimated at 30 (16–43) %.

Conclusions: The results suggest that MC is generally progressive in middle age and furthermore is heritable. Since MC is associated with disc degeneration, which is also heritable, further work on potential shared mechanisms is needed.

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Stereoelectroencephalography in Children and Adolescents With Difficult-to-Localize Refractory Focal Epilepsy

Stereoelectroencephalography in Children and Adolescents With Difficult-to-Localize Refractory Focal Epilepsy

Neurosurgery 75:258–268, 2014

Although stereoelectroencephalography (SEEG) has been shown to be a valuable tool for preoperative decision making in focal epilepsy, there are few reports addressing the utility and safety of SEEG methodology applied to children and adolescents.

OBJECTIVE: To present the results of our early experience using SEEG in pediatric patients with difficult-to-localize epilepsy who were not considered candidates for subdural grid evaluation.

METHODS: Thirty children and adolescents with the diagnosis of medically refractory focal epilepsy (not considered ideal candidates for subdural grids and strip placement) underwent SEEG implantation. Demographics, electrophysiological localization of the hypothetical epileptogenic zone, complications, and seizure outcome after resections were analyzed.

RESULTS: Eighteen patients (60%) underwent resections after SEEG implantations. In patients who did not undergo resections (12 patients), reasons included failure to localize the epileptogenic zone (4 patients); multifocal epileptogenic zone (4 patients); epileptogenic zone located in eloquent cortex, preventing resection (3 patients); and improvement in seizures after the implantation (1 patient). In patients who subsequently underwent resections, 10 patients (55.5%) were seizure free (Engel class I) and 5 patients (27.7%) experienced seizure improvement (Engel class II or III) at the end of the follow-up period (mean, 25.9 months; range, 12 to 47 months). The complication rate in SEEG implantations was 3%.

CONCLUSION: The SEEG methodology is safe and should be considered in children/ adolescents with difficult-to-localize epilepsy. When applied to highly complex and difficult-to-localize pediatric patients, SEEG may provide an additional opportunity for seizure freedom in association with a low morbidity rate.

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Morphological predictors of intraprocedural rupture during coil embolization of ruptured cerebral aneurysms

Morphological predictors of intraprocedural rupture for coiling

J Neurosurg 121:605–612, 2014

This study aimed to investigate morphological predictors of intraprocedural rupture (IPR) during coil embolization of ruptured cerebral aneurysms.

Methods. A retrospective analysis was conducted in 322 consecutive patients with ruptured cerebral aneurysms who were treated with coil embolization over an 8-year period from January 2005 to December 2012. The authors analyzed all available data with emphasis on morphological characteristics of the aneurysm as shown on baseline angiography in relation to IPR. Regarding aneurysm morphology, the authors classified patients according to multilobulation, presence of a daughter sac, and presence of a small basal outpouching (SBO).

Results. The incidence of IPR was 4.8% (16 of 332). In terms of aneurysm configuration, the presence of multilobulation (100.0% [16 of 16] in the IPR group vs 89.2% [282 of 316] in the non-IPR group, p = 0.388) and daughter sac (75.0% [12 of 16] in the IPR group vs 59.2% [187 of 316] in the non-IPR group, p = 0.208) were not significantly associated with IPR. However, SBO, found in 9% (30 of 332) of the study population, was significantly associated with IPR (56.3% [9 of 16] in the IPR group vs 6.7% [21 of 316] in the non-IPR group, OR 18.06, p < 0.0001).

Conclusions. Based on the authors’ data, the more general groups of multilobulation and daughter sac were not significantly associated with IPR, although the more specific subgroup with an SBO was. More confirmation studies on these results are required, but they point to the possibility that SBO (with its possible connection to basal rupture) is an important morphological risk factor for IPR during coiling. In addition, future comparison of coiling and clipping treatment for ruptured aneurysms associated with an SBO seems necessary.

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Are parenchymal AVMs congenital lesions?

Are parenchymal AVMs congenital lesions?

Neurosurg Focus 37 (3):E2, 2014

A long-held dogma in neurosurgery is that parenchymal arteriovenous malformations (AVMs) are congenital. However, there is no strong evidence supporting this theory.

An increasing number of documented cases of de novo formation of parenchymal AVMs cast doubt on their congenital nature and suggest that indeed the majority of these lesions may form after birth.

Further evidence suggesting the postnatal development of parenchymal AVMs comes from the exceedingly rare diagnosis of these lesions in utero despite the widespread availability of high-resolution imaging modalities such as ultrasound and fetal MRI.

The exact mechanism of AVM formation has yet to be elucidated, but most likely involves genetic susceptibility and environmental triggering factors.

In this review, the authors report 2 cases of de novo AVM formation and analyze the evidence suggesting that they represent an acquired condition.

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Classification of degenerative segment disease in adults with deformity of the lumbar or thoracolumbar spine

Classification of degenerative segment disease in adults with deformity of the lumbar or thoracolumbar spine

Eur Spine J (2014) 23:1815–1824

Lumbar and thoracolumbar deformity in the adult is a condition with impairment of health status that can need surgical treatment. In contrast with adolescent deformity, where magnitude of the curve plays a significant role in surgical indication, the aspects relevant in adult deformity are pain and dysfunction that correlate with segment degeneration and imbalance. Previous classifications of adult deformity have been of little use for surgical planning.

Methods Chart review and classification of radiographic and clinical findings. A classification of degenerative disc disease based on distribution of diseased segments and balance status of the spine is presented.

Results Four main categories are presented: Type I (limited nonapical segment disease), Type II (limited apical segment disease), Type III (extended segment disease— apical and nonapical), Type IV (imbalanced spine: IVa, sagittally imbalanced; IVb, sagittally and coronally imbalanced).

Discussion and conclusion Types I and II can be treated by fusion of a selective area of the curve. Type III needs fusion of all the extension of the coronal curve. Type IV usually needs aggressive corrective procedures, frequently including posterior tricolumnar osteotomies. This classification permits interpreting the extension and magnitude of the disease and can help establish a surgical plan regarding selective fusion and methods of sagittal correction. Future research is needed to validate the classification.

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Augmented reality in the surgery of cerebral arteriovenous malformations

Augmented reality in the surgery of cerebral arteriovenous malformations

Acta Neurochir (2014) 156:1769–1774

Augmented reality technology has been used for intraoperative image guidance through the overlay of virtual images, from preoperative imaging studies, onto the realworld surgical field. Although setups based on augmented reality have been used for various neurosurgical pathologies, very few cases have been reported for the surgery of arteriovenous malformations (AVM). We present our experience with AVM surgery using a system designed for image injection of virtual images into the operating microscope’s eyepiece, and discuss why augmented reality may be less appealing in this form of surgery.

Methods N=5 patients underwent AVM resection assisted by augmented reality. Virtual three-dimensional models of patients’ heads, skulls, AVM nidi, and feeder and drainage vessels were selectively segmented and injected into the microscope’s eyepiece for intraoperative image guidance, and their usefulness was assessed in each case.

Results Although the setup helped in performing tailored craniotomies, in guiding dissection and in localizing drainage veins, it did not provide the surgeon with useful information concerning feeder arteries, due to the complexity of AVM angioarchitecture.

Conclusion The difficulty in intraoperatively conveying useful information on feeder vessels may make augmented reality a less engaging tool in this form of surgery, and might explain its underrepresentation in the literature. Integrating an AVM’s hemodynamic characteristics into the augmented rendering could make it more suited to AVM surgery.

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Microsurgery for cerebral arteriovenous malformations: postoperative outcomes and predictors of complications in 264 cases

AVM PF

Neurosurg Focus 37 (3):E10, 2014

The authors conducted a study to assess the safety and efficacy of microsurgical resection of arteriovenous malformations (AVMs) and determine predictors of complications.

Methods. A total of 264 patients with cerebral AVMs were treated with microsurgical resection between 1994 and 2010 at the Jefferson Hospital for Neuroscience. A review of patient data was performed, including initial hemorrhage, clinical presentation, Spetzler-Martin (SM) grade, treatment modalities, clinical outcomes, and obliteration rates. Univariate and multivariate analyses were used to determine predictors of operative complications.

Results. Of the 264 patients treated with microsurgery, 120 (45%) patients initially presented with hemorrhage. There were 27 SM Grade I lesions (10.2%), 101 Grade II lesions (38.3%), 96 Grade III lesions (36.4%), 31 Grade IV lesions (11.7%), and 9 Grade V lesions (3.4%). Among these patients, 102 (38.6%) had undergone prior endovascular embolization. In all patients, resection resulted in complete obliteration of the AVM. Complications occurred in 19 (7.2%) patients and resulted in permanent neurological deficits in 5 (1.9%). In multivariate analysis, predictors of complications were increasing AVM size (OR 3.2, 95% CI 1.5–6.6; p = 0.001), increasing number of embolizations (OR 1.6, 95% CI 1.1–2.2; p = 0.01), and unruptured AVMs (OR 2.7, 95% CI 1–7.2; p = 0.05).

Conclusions. Microsurgical resection of AVMs is highly efficient and can be undertaken with low rates of morbidity at high-volume neurovascular centers. Unruptured and larger AVMs were associated with higher complication rates.

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Outcomes After Surgery and Radiotherapy for Spinal Myxopapillary Ependymoma

Spinal Myxopapillary Ependymoma

Neurosurgery 75:205–214, 2014

The role of radiotherapy after surgery for myxopapillary ependymoma (MPE) is unclear.

OBJECTIVE: To review long-term outcomes after surgery, with or without radiation, for spinal MPE.

METHODS: Fifty-one patients with spinal MPE treated from 1968 to 2007 were included. Associations between clinical variables and overall survival (OS), progressionfree survival (PFS), and local control (LC) were tested with Cox regression analysis.

RESULTS: The median age at diagnosis was 35 years (range, 8-63 years). Twenty patients (39%) had surgery alone, 30 (59%) had surgery plus radiotherapy (RT), and 1 (2%) had RT only. At a median follow-up of 11 years (range, 0.2-37 years), 10-year OS, PFS, and LC for the entire group were 93%, 63%, and 67%, respectively. Nineteen patients (37%) had disease recurrence, and the recurrence was mostly local (79%). Twenty-eight of 50 patients who had surgery (56%) had gross total resection; 10-year LC was 56% after surgery vs 92% after surgery and RT (log-rank P = .14); the median time of LC was 10.5 years for patients receiving gross total resection plus RT, and 4.75 years for gross total resection only (P = .03). Among 16 patients with subtotal resection and follow-up data, 10-year LC was 0% after surgery vs 65% for surgery plus RT (log-rank P = .008). On multivariate analyses adjusting for resection type, age older that 35 years at diagnosis and receipt of adjuvant radiation were associated with improved PFS (hazard ratio [HR]: 0.14, P = .003 and HR: 0.45, P = .009) and LC (HR: 0.22, P = .02 and HR: 0.45, P = .009).

CONCLUSION: Postoperative radiotherapy after resection of MPE was associated with improved PFS and LC.

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Retrosigmoid removal of small acoustic neuroma: curative tumor removal with preservation of function

Retrosigmoid removal of small acoustic neuroma

J Neurosurg 121:554–563, 2014

Management of small acoustic neuromas (ANs) consists of 3 options: observation with imaging followup, radiosurgery, and/or tumor removal. The authors report the long-term outcomes and preservation of function after retrosigmoid tumor removal in 44 patients and clarify the management paradigm for small ANs.

Methods. A total of 44 consecutively enrolled patients with small ANs and preserved hearing underwent retrosigmoid tumor removal in an attempt to preserve hearing and facial function by use of intraoperative auditory monitoring of auditory brainstem responses (ABRs) and cochlear nerve compound action potentials (CNAPs). All patients were younger than 70 years of age, had a small AN (purely intracanalicular/cerebellopontine angle tumor ≤ 15 mm), and had serviceable hearing preoperatively. According to the guidelines of the Committee on Hearing and Equilibrium of the American Academy of Otolaryngology–Head and Neck Surgery Foundation, preoperative hearing levels of the 44 patients were as follows: Class A, 19 patients; Class B, 17; and Class C, 8. The surgical technique for curative tumor removal with preservation of hearing and facial function included sharp dissection and debulking of the tumor, reconstruction of the internal auditory canal, and wide removal of internal auditory canal dura.

Results. For all patients, tumors were totally removed without incidence of facial palsy, death, or other complications. Total tumor removal was confirmed by the first postoperative Gd-enhanced MRI performed 12 months after surgery. Postoperative hearing levels were Class A, 5 patients; Class B, 21; Class C, 11; and Class D, 7. Postoperatively, serviceable (Class A, B, or C) and useful (Class A or B) levels of hearing were preserved for 84% and 72% of patients, respectively. Better preoperative hearing resulted in higher rates of postoperative hearing preservation (p = 0.01); preservation rates were 95% among patients with preoperative Class A hearing, 88% among Class B, and 50% among Class C. Reliable monitoring was more frequently provided by CNAPs than by ABRs (66% vs 32%, p < 0.01), and consistently reliable auditory monitoring was significantly associated with better rates of preservation of useful hearing. Long-term follow-up by MRI with Gd administration (81 ± 43 months [range 5–181 months]; median 7 years) showed no tumor recurrence, and although the preserved hearing declined minimally over the long-term postoperative follow-up period (from 39 ± 15 dB to 45 ± 11 dB in 5.1 ± 3.1 years), 80% of useful hearing and 100% of serviceable hearing remained at the same level.

Conclusions. As a result of a surgical technique that involved sharp dissection and internal auditory canal reconstruction with intraoperative auditory monitoring, retrosigmoid removal of small ANs can lead to successful curative tumor removal without long-term recurrence and with excellent functional outcome. Thus, the authors suggest that tumor removal should be the first-line management strategy for younger patients with small ANs and preserved hearing.

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Lateral inferior cerebellar peduncle approach to dorsolateral medullary cavernous malformation

Dorsolateral medullary cavernous malformations

J Neurosurg 121:723–729, 2014

Brainstem cavernous malformations (BSCMs) present a unique therapeutic challenge to neurosurgeons. Resection of BSCMs is typically reserved for lesions that reach pial or ependymal surfaces. The current study investigates the lateral inferior cerebellar peduncle as a corridor to dorsolateral medullary BSCMs.

Methods. In this retrospective review, the authors present the cases of 4 patients (3 women and 1 man) who had a symptomatic dorsolateral cavernous malformation with radiographic and clinical evidence of hemorrhage.

Results. All patients underwent excision of the cavernous malformation via a far-lateral suboccipital craniotomy through the foramen of Luschka and with an incision in the inferior cerebellar peduncle. On intraoperative examination, 2 of the 4 patients had hemosiderin staining on the surface of the peduncle. All lesions were completely excised and all patients had a good or excellent outcome (modified Rankin Scale scores of 0 or 1).

Conclusions. This case series illustrates that intrinsic lesions of the dorsolateral medulla can be safely removed laterally through the foramen of Luschka and the inferior cerebellar peduncle.

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Twenty-Year Follow-up of Flow Reversal and Revascularization for a Giant Serpentine Basilar Artery Aneurysm

Twenty-Year Follow-up of Flow Reversal and Revascularization for a Giant Serpentine Basilar Artery Aneurysm

Operative Neurosurgery 10:E493–E497, 2014

Current microsurgical and endovascular therapies have offered little advancement for the treatment of complex vertebrobasilar aneurysms. The outcome of patients with these rare lesions has remained poor, despite sometimes heroic measures.

CLINICAL PRESENTATION: The authors report a case of a 65-year-old man who 20 years earlier had presented with symptoms suggestive of brainstem compression. Imaging at the time revealed a giant, serpentine aneurysm of the basilar artery. The patient was treated with superficial temporal artery to superior cerebellar artery bypass and decompression of the aneurysm contents. Twenty years after this treatment, the patient remains functionally intact with few sequelae from his treatment or the pathology. Follow-up imaging reveals thrombosis of the aneurysm without ischemic damage to the brainstem.

CONCLUSION: This case demonstrates that good functional outcomes are possible for select complex posterior circulation aneurysms by using flow reversal and revascularization; however, at this time, we are unable to predict for which patients this strategy will be successful.

KEY WORDS:

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Surgical technique and effectiveness of microendoscopic discectomy for large uncontained lumbar disc herniations: a prospective, randomized, controlled study with 8 years of follow-up

Surgical technique and effectiveness of microendoscopic discectomy for large uncontained lumbar disc herniations

Eur Spine J (2014) 23:1992–1999

There is a long-held concept among spine surgeons that endoscopic lumbar discectomy procedures are reserved for small-contained disc herniation; 8-year follow-up has not been reported. The purpose of this study is to assess microendoscopic discectomy (MED) in patients with large uncontained lumbar disc herniation (the anteroposterior diameter of the extruded fragment is 6–12 mm or more on axial cuts of MRI) and report long-term outcome.

Methods One hundred eighty-five patients with MED or standard open discectomy underwent follow-up for 8 years. Primary (clinical) outcomes data included Numerical Rating Scale (NRS) for back and leg symptoms and Oswestry Disability Index (ODI) to quantify pain and disability, respectively. Secondary (objective) outcomes data included operative time, blood loss, postoperative analgesics, length of hospital stay, time to return to work, reoperation and complication rate, patient satisfaction index (PSI), and modified (MacNab) criteria.

Results At the end of the follow-up, the leg pain relief was statistically significant for both groups. NRS back pain, ODI, PSI and MacNab criteria showed significant deterioration for control group. Secondary outcomes data of MED group were significantly better than the control group.

Conclusions Large, uncontained, lumbar disc herniations can be sufficiently removed using MED which is an effective alternative to open discectomy procedures with remarkable long-term outcome. Although the neurological outcome of the two procedures is the same, the morbidity of MED is significantly less than open discectomy. Maximum benefit can be gained if we adhere to strict selection criteria. The optimum indication is single- or multi-level radiculopathy secondary to a single-level, large, uncontained, lumbar disc herniation.

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Transdural indocyanine green video-angiography of vascular malformations

Transdural indocyanine green video-angiography of vascular malformations

Acta Neurochir (2014) 156:1761–1767

The role of indocyanine green videoangiography (ICG-VA) in the surgical resection of vascular malformations has been largely described; conversely, the utility of ICG-VA before dural opening (transdural ICG-VA) in this situation remains unclear. The aim of this study is to present the application of transdural ICG-VA in a consecutive series of patients in order to explore the potential provided by a transdural visualisation of vascular malformations.

Method We retrospectively analysed the application of intraoperative ICG-VA before dural opening in 15 consecutive patients who underwent surgical resection of vascular malformations. The cases included 12 cerebral arterio-venous malformations (AVMs), 2 cerebral dural arterio-venous fistulas (dAVFs) and 1 spinal arterio-venous fistula (AVF).

Results ICG-VA before dural opening allowed the visualisation of the site and extension of the malformation in 13 out of 15 cases, whilst arterial feeders and venous drainages were identified in 9 out of 15 cases. In two patients with dAVF, the point of fistula could be transdurally identified through ICGVA. In 14% of cases, the size of bone flap designed on neuronavigation data was then modified according to transdural ICG-VA findings.

Conclusions Transdural ICG-VA proved an efficient tool that allows optimising the exposure of the malformation, performing a safe dural opening and identifying dural vascular connections of the lesion.

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