Correction to: Rathke's cleft cysts: a 6-year experience of surgery vs. observation with comparative volumetric analysis.

The original version of this article unfortunately contained errors in legend numbers of Figure 2 caption.

Rathke's cleft cysts: a 6-year experience of surgery vs. observation with comparative volumetric analysis.

BACKGROUND: Rathke's cleft cysts (RCCs) are common sellar lesions. Their management remains controversial, particularly when small or asymptomatic. Herein we review a consecutive series of RCC patients managed with surgery or observation. METHODS: All patients with a new diagnosis of presumed RCC, based on MRI, from February 2012-March 2018 were retrospectively divided into observational and surgical cohorts based on an intent-to-treat model. The cohorts were compared for clinical presentation, and cyst volume. The observational cohort was followed for change in cyst size. The surgical cohort was followed for changes in endocrinopathy, visual symptoms, headache and recurrence. RESULTS: Of 90 patients (mean age 36.7 ± 19.4 years; 68% female), 60% (n = 54) were in the observational cohort and 40% (n = 36) in the surgical cohort. Average follow-up was 13 ± 23 months in the observational cohort and 24 ± 19 months in the surgical group. In comparing the cohorts, mean ages were similar with more women in the surgical group (81% vs. 56%, p = 0.04). Most patients in the observational cohort had incidentally-discovered RCCs (n = 50, 88%) as opposed to the surgical cohort (n = 6, 17%). The surgical cohort had higher rates of headache (89% vs 26%, p < 0.001), endocrinopathy (36% vs 0%, p < 0.001), and visual dysfunction (19% vs 0%, p = 0.001). Mean cyst volume and maximal cyst dimensions were greater in the surgical cohort (0.94 ± 0.77 cm3 and 14.2 ± 4.1 mm), compared to the observational cohort (0.1 ± 0.14 cm3 and 6.4 ± 3 mm), (p < 0.001). Among the 53% (n = 30/54) of patients in the observational group with follow-up, 3 (10%) had spontaneous RCC shrinkage, 1 (3%) had modest asymptomatic growth (at 10 months from initial MRI), and 87% had stable cyst size. Of the 36 patients recommended to have surgery, 89% (n = 32) did so. Post-operatively, complete or partial resolution of headache, endocrinopathy and visual dysfunction were documented in 90% (n = 28/30), 75% (n = 10/12), and 100% (n = 7/7), respectively. On follow-up MRI, 8 (22%) patients had some cyst reaccumulation, of whom 3 (8%) were symptomatic and underwent uneventful reoperation. No major complications such as hematoma, CSF leak, new endocrinopathy or visual deficits occurred. CONCLUSION: From this consecutive series, a majority (60%) of RCCs do not appear to warrant surgical intervention and have a low risk of cyst progression. However, surgical cyst removal appears to be indicated and safe for patients with larger, symptomatic RCCs. Simple cyst drainage has a high rate of improvement in pituitary gland function, visual function and headache resolution with low complication rates and symptomatic recurrence risk. These findings stress the importance of careful case selection and potential utility of volumetric assessment for patients with RCCs.

Efficacy of postoperative seizure prophylaxis in intra-axial brain tumor resections.

The effectiveness of seizure prophylaxis in controlling postoperative seizures following craniotomy for tumor resection is unclear. Most patients are seizure-free before surgery. To prevent seizures, it is common to treat tumor craniotomy patients postoperatively with an antiepileptic drug (AED). The authors retrospectively analyzed seizure occurrence with and without postoperative prophylactic AEDs. Between 2005 and 2011 at the authors' institution, 588 patients underwent craniotomy for brain tumors and were screened. Data on seizures, AED use, histopathology, comorbidities, complications, and follow-up were collected. Exclusion criteria included lack of follow-up data, previous operation, preoperative seizures, or preoperative AED prophylaxis. The incidence of postoperative seizures in patients with and without prophylactic AEDs was compared using logistic regression analysis. A total of 202 patients (50.5% female) were included. The most common tumor diagnosis was metastasis (42.6%). Of the 202 patients, 66.3% were prescribed prophylactic AED after surgery. Forty-six of 202 (22.8%) suffered a postoperative seizure. The odds of seizure for patients on prophylactic AED was 1.62 times higher than those not on AED (p = 0.2867). No difference was found in seizure occurrence between patients with glioblastoma multiforme compared with other tumor types (odds ratio 1.75, p = 0.1468). No difference was found in time-to-seizure between the two groups (hazard ratio 1.38, p = 0.3776). These data show no statistically significant benefit to prophylactic postoperative AED and a nonsignificant trend for increased seizure risk with AEDs. A randomized, placebo-controlled trial is needed to clarify the benefit of postoperative AED use for brain tumor resection.

Trautmann's triangle anatomy with application to posterior transpetrosal and other related skull base procedures.

Trautmann's triangle (TT) faces the cerebellopontine angle and is exposed during posterior transpetrosal approaches. However, reports on the morphometric analysis of this structure are lacking in the literature. The goal was to better understand this important operative corridor. TT was exposed from an external approach (transmastoid) in ten cadavers (20 sides) and from an internal approach on 20 dry adult temporal bones. Measurements included calculation of the area of TT and the distance of the endolymphatic sac from the anterior border of the sigmoid sinus. The area range of TT was 45-210 mm(2) (mean 151 mm(2); SD 37 mm(2)). Three types of triangles were identified based on area. Type I triangles had areas less than 75 mm(2), Type II areas were 75-149 mm(2), and Type III areas were 150 mm(2) and greater. These types were observed in 37.5%, 35%, and 27.5% of sides, respectively. The distance from the jugular bulb's anterior border to the posterior border of the posterior semicircular canal ranged from 6 to 11 mm (mean 8.5 mm). The endolymphatic sac was located in the inferior portion of TT and traveled anterior to the sigmoid sinus. The horizontal distance from the anterior edge of the sigmoid sinus to the posterior edge of the endolymphatic sac ranged from 0 to 13.5 mm (mean 9 mm). Additional anatomic knowledge regarding TT may improve neurosurgical procedures in this region by avoiding intrusion into the endolymphatic sac and sigmoid sinus.

Surgery for vestibular schwannomas: a systematic review of complications by approach.

OBJECT: Various studies report outcomes of vestibular schwannoma (VS) surgery, but few studies have compared outcomes across the various approaches. The authors conducted a systematic review of the available data on VS surgery, comparing the different approaches and their associated complications. METHODS: MEDLINE searches were conducted to collect studies that reported information on patients undergoing VS surgery. The authors set inclusion criteria for such studies, including the availability of follow-up data for at least 3 months, inclusion of preoperative and postoperative audiometric data, intraoperative monitoring, and reporting of results using established and standardized metrics. Data were collected on hearing loss, facial nerve dysfunction, persistent postoperative headache, CSF leak, operative mortality, residual tumor, tumor recurrence, cranial nerve (CN) dysfunction involving nerves other than CN VII or VIII, and other neurological complications. The authors reviewed data from 35 studies pertaining to 5064 patients who had undergone VS surgery. RESULTS: The analyses for hearing loss and facial nerve dysfunction were stratified into the following tumor categories: intracanalicular (IC), size (extrameatal diameter) < 1.5 cm, size 1.5-3.0 cm, and size > 3.0 cm. The middle cranial fossa approach was found to be superior to the retrosigmoid approach for hearing preservation in patients with tumors < 1.5 cm (hearing loss in 43.6% vs 64.3%, p < 0.001). All other size categories showed no significant difference between middle cranial fossa and retrosigmoid approaches with respect to hearing loss. The retrosigmoid approach was associated with significantly less facial nerve dysfunction in patients with IC tumors than the middle cranial fossa method was; however, neither differed significantly from the translabyrinthine corridor (4%, 16.7%, 0%, respectively, p < 0.001). The middle cranial fossa approach differed significantly from the translabyrinthine approach for patients with tumors < 1.5 cm, whereas neither differed from the retrosigmoid approach (3.3%, 11.5%, and 7.2%, respectively, p = 0.001). The retrosigmoid approach involved less facial nerve dysfunction than the middle cranial fossa or translabyrinthine approaches for tumors 1.5-3.0 cm (6.1%, 17.3%, and 15.8%, respectively; p < 0.001). The retrosigmoid approach was also superior to the translabyrinthine approach for tumors > 3.0 cm (30.2% vs 42.5%, respectively, p < 0.001). Postoperative headache was significantly more likely after the retrosigmoid approach than after the translabyrinthine approach, but neither differed significantly from the middle cranial fossa approach (17.3%, 0%, and 8%, respectively; p < 0.001). The incidence of CSF leak was significantly greater after the retrosigmoid approach than after either the middle cranial fossa or translabyrinthine approaches (10.3%, 5.3%, 7.1%; p = 0.001). The incidences of residual tumor, mortality, major non-CN complications, residual tumor, tumor recurrence, and dysfunction of other cranial nerves were not significantly different across the approaches. CONCLUSIONS: The middle cranial fossa approach seems safest for hearing preservation in patients with smaller tumors. Based on the data, the retrosigmoid approach seems to be the most versatile corridor for facial nerve preservation for most tumor sizes, but it is associated with a higher risk of postoperative pain and CSF fistula. The translabyrinthine approach is associated with complete hearing loss but may be useful for patients with large tumors and poor preoperative hearing.

Surgery for extratemporal nonlesional epilepsy in children: a meta-analysis.

PURPOSE: Previous small studies have demonstrated that seizure outcomes following surgery for extratemporal lobe epilepsy (ETLE) in children are worse than those for temporal lobe epilepsy. We have conducted a meta-analysis of the available literature to better understand ETLE surgical outcomes in children. METHODS: We searched PubMed (1990-2009) for appropriate studies using the following terms: ETLE, ETLE surgery, ETLE surgery outcome, frontal lobe epilepsy, occipital lobe epilepsy, and parietal lobe epilepsy. Our collected data included patient age at seizure onset and surgery, the cerebral lobe involved with epileptogenesis, MRI findings, predominant seizure semiology, intracranial monitoring use (electrode implantation), epileptic region histopathology, and postoperative seizure outcome. Statistical analysis was performed to determine associations among these variables and postoperative outcome. RESULTS: Ninety-five patients from 17 studies satisfied the inclusion criteria. Pathological findings (p = 0.039) and seizure type (p = 0.025) were significantly associated with outcome: A larger proportion of patients with cortical dysplasia and complex partial seizures experienced better outcomes. Age at surgery (p = 0.073) and the cerebral resection site (p = 0.059) were marginally associated with seizure outcome. CONCLUSIONS: This study confirms previous reports: Surgical outcomes for ETLE epilepsy are significantly worse than those for temporal lobe epilepsy. The reasons for this difference may include the diffuse nature of the pathology involved in ETLE, difficulty in localizing the seizure focus in young children, and involvement of "eloquent" nonresectable cortex in epileptogenesis. Because of the reporting variability among different epilepsy centers, more uniform protocols are necessary for fair evaluation and comparison of outcomes among the different centers.

Surgery for extratemporal nonlesional epilepsy in adults: an outcome meta-analysis.

PURPOSE: To better evaluate surgery for extratemporal lobe epilepsy (ETLE) in adults, we conducted a meta-analysis of previous studies that analyzed postoperative seizure outcomes for ETLE. METHODS: After searching PubMed for appropriate studies, patient data were reviewed, and data on patients who fit the authors' criteria were extracted. Statistical analysis compared each variable with surgical outcome to determine if an association existed. RESULTS: For the 131 patients who were included in the analysis, the age at surgery, age of seizure onset, and duration of epilepsy were not found to be statistically and significantly related to seizure outcome. Similarly, seizure semiology, abnormality on magnetic resonance imaging, lateralization of the seizures, the need for intracranial monitoring, pathological findings, and the type and location of surgery did not appear to be associated with outcome. CONCLUSIONS: This meta-analysis confirms the findings of other centers: ETLE surgical outcomes are less desirable than those for temporal lobe epilepsy. None of the factors studied in adults showed significant association with outcome. Contrary to some reports, shortening the duration of epilepsy by pursuing surgery as early as possible also does not appear to improve outcomes. The creation of standard protocols among epilepsy centers is needed to allow for a detailed evaluation of outcomes across different centers and, ultimately, to better assess the factors associated with improved outcomes.

The Supraorbital Eyebrow Craniotomy for Intra- and Extra-Axial Brain Tumors: A Single-Center Series and Technique Modification.

BACKGROUND: The supraorbital (SO) eyebrow craniotomy provides minimally invasive access to the anterior and middle fossae and parasellar region. OBJECTIVE: To present a series of patients treated with the SO approach to assess outcomes, the impact of endoscopy, and describe a modified pericranial flap aimed at reducing postoperative frontalis paresis and hypesthesia. METHODS: A retrospective analysis was undertaken of our prospective database of patients who underwent SO craniotomy for tumor/cyst removal. Patients were evaluated based on pathology, utility of endoscopy, extent of resection, complications, and functional/esthetic recovery. RESULTS: From 2007 to 2018, 129 operations were performed in 117 patients (54% women; mean age 60 ± 16.5 yr). The most common lesions were meningiomas (43%), gliomas (15%), and metastases (15%). Prior surgery and/or radiation had been performed in 37% and 26% of patients, respectively. Endoscopy was used in 76 (61%) operations and allowed more complete tumor removal in 38 (50%). For first-time operations, gross-total removal was achieved in 78%. Major complications included stroke (3%), cranial nerve deficit (3%), acute hematoma (1%), and cerebrospinal fluid leak (1%). The modified pericranial flap technique used in 18 recent patients resulted in a shorter duration of transient frontalis paresis and forehead hypesthesia with complete functional recovery in all 18. CONCLUSION: The SO craniotomy is an effective keyhole approach for intra- and extra-axial tumors. Endoscopic assistance may allow additional tumor removal in almost 30% of the cases. The modified pericranial flap appears to accelerate functional recovery, although additional patients and follow-up are required to better assess this technique.

Vascularity of meningiomas.

Information on the vascular supply to meningiomas is critical to the neurosurgeon. Most meningiomas are supplied by the external carotid artery, though many get pial contribution as well. Angiogenesis is critical for these neoplasms to grow. Vascular endothelial growth factor (VEGF) has been a popular target of research to decrease angiogenesis. Peritumoral brain edema (PTBE) is occasionally seen in meningiomas, which makes surgical resection more challenging. The exact cause of PTBE remains unclear, but a number of factors have been postulated to contribute. Assessment of the vascularity of meningiomas is best carried out with angiography, but noninvasive techniques are improving, diminishing the need for more invasive imaging. Embolization of tumors can be performed to minimize perioperative blood loss and potentially lower surgical morbidity. However, it has not been shown to improve outcomes, and procedural risks exist. Higher grade tumors commonly have higher vascularity. Higher vascular meningiomas are more likely to recur and have higher levels of VEGF. The vascularity of meningiomas remains a topic of interest and is the focus of many research projects.

Hospital Length of Stay and Readmission Rate for Neurosurgical Patients.

BACKGROUND: Hospital readmission rate has become a major indicator of quality of care, with penalties given to hospitals with high rates of readmission. At the same time, insurers are increasing pressure for greater efficiency and reduced costs, including decreasing hospital lengths of stay (LOS). OBJECTIVE: To analyze the authors' service to determine if there is a relationship between LOS and readmission rates. METHODS: Records of patients admitted to the authors' institution from October 2007 through June 2014 were analyzed for several data points, including initial LOS, readmission occurrence, admitting and secondary diagnoses, and discharge disposition. RESULTS: Out of 9409 patient encounters, there were 925 readmissions. Average LOS was 6 d. Univariate analysis indicated a higher readmission rate with more diagnoses upon admission (P < .001) and an association between insurance type and readmission (P < .001), as well as decreasing average yearly LOS (P = .0045). Multivariate analysis indicated statistically significant associations between longer LOS (P = .03) and government insurance (P < .01). CONCLUSION: A decreasing LOS over time has been associated with an increasing readmission rate at the population level. However, at the individual level, a prolonged LOS was associated with a higher risk of readmission. This was attributed to patient comorbidities. However, this increasing readmission rate may represent many factors including patients' overall health status. Thus, the rate of readmission may represent a burden of illness rather than a valid metric for quality of care.

Intracranial Connections of the Vertebral Venous Plexus: Anatomical Study with Application to Neurosurgical and Endovascular Procedures at the Craniocervical Junction.

BACKGROUND: Descriptions of intracranial extensions of vertebral venous plexuses are lacking. OBJECTIVE: To identify vertebral venous plexuses at the craniocervical junction in cadavers and describe them. METHODS: The authors dissected 15 ink-injected, formalin-fixed, adult cadaveric heads and measured cranial extensions of the spinal venous plexuses. RESULTS: All specimens had vertebral venous plexuses at the craniocervical junction composed of multiple interwoven vessels concentrated anteriorly (anterior vertebral plexuses), posteriorly (posterior vertebral venous plexuses), and laterally (lateral vertebral venous plexuses). Veins making up the plexus tended to be largest for the anterior internal vertebral venous plexus. On 33%, a previously unnamed lateral internal vertebral venous plexus was identified that connected to the lateral marginal sinus. The anterior external vertebral venous plexus connected to the basilar venous plexus via transclival emissary veins in 13%; remaining veins connected either intracranially via small perforating branches through the anterior atlanto-occipital membrane (33%) or had no direct gross connections inside the cranium (53%). The anterior internal vertebral plexus, which traveled between layers of the posterior longitudinal ligament, connected to the anterior half of the marginal sinus in 33% and anterolateral parts of the marginal sinus in 20%. The posterior internal venous plexus connected to the posterior aspect of the marginal sinus on 80% and into the occipital sinus in 13.3%. The posterior external venous plexus connected to veins of the hypoglossal canal in 20% and into the posterior aspect of the marginal sinus in 13.3%. CONCLUSION: Knowledge of these connections is useful to neurosurgeons and interventional radiologists.

Brainstem metastases treated with Gamma Knife stereotactic radiosurgery: the Indiana University Health experience.

Brainstem metastases offer a unique challenge in cancer treatment, yet stereotactic radiosurgery (SRS) has proven to be an effective modality in treating these tumors. This report discusses the clinical outcomes of patients with brainstem metastases treated at Indiana University with Gamma Knife (GK) radiosurgery from 2008 to 2016. 19 brainstem metastases from 14 patients who had follow-up brain imaging were identified. Median tumor volume was 0.04 cc (range: 0.01-2.0 cc). Median prescribed dose was 17.5 Gy to the 50% isodose line (range: 14-22 Gy). Median survival after GK SRS treatment to brainstem lesion was 17.2 months (range: 2.8-45.6 months). The experience at Indiana University confirms the safety and efficacy of range of GK SRS prescription doses (14-22 Gy) to brainstem metastases.

Toxicity of Radiosurgery for Brainstem Metastases.

BACKGROUND: Although stereotactic radiosurgery (SRS) is an effective modality in the treatment of brainstem metastases (BSM), radiation-induced toxicity remains a critical concern. To better understand how severe or life-threatening toxicity is affected by the location of lesions treated in the brainstem, a review of all available studies reporting SRS treatment for BSM was performed. METHODS: Twenty-nine retrospective studies investigating SRS for BSM were reviewed. RESULTS: The rates of grade 3 or greater toxicity, based on the Common Terminology Criteria for Adverse Events, varied from 0 to 9.5% (mean 3.4 ± 2.9%). Overall, the median time to toxicity after SRS was 3 months, with 90% of toxicities occurring before 9 months. A total of 1243 cases had toxicity and location data available. Toxicity rates for lesions located in the medulla were 0.8% (1/131), compared with midbrain and pons, respectively, 2.8% (8/288) and 3.0% (24/811). CONCLUSIONS: Current data suggest that brainstem substructure location does not predict for toxicity and lesion volume within this cohort with median tumor volumes 0.04-2.8 cc does not predict for toxicity.

Efficacy of phosphorus-32 brachytherapy without external-beam radiation for long-term tumor control in patients with craniopharyngioma.

OBJECT Radioactive phosphorus-32 (P32) has been used as brachytherapy for craniopharyngiomas with the hope of providing local control of enlarging tumor cysts. Brachytherapy has commonly been used as an adjunct to the standard treatment of surgery and external-beam radiation (EBR). Historically, multimodal treatment, including EBR, has shown tumor control rates as high as 70% at 10 years after treatment. However, EBR is associated with significant long-term risks, including visual deficits, endocrine dysfunction, and cognitive decline. Theoretically, brachytherapy may provide focused local radiation that controls or shrinks a symptomatic cyst without exposing the patient to the risks of EBR. For this study, the authors reviewed their experiences with craniopharyngioma patients treated with P32 brachytherapy as the primary treatment without EBR. The authors reviewed these patients' records to evaluate whether this strategy effectively controls tumor growth, thus avoiding the need for further surgery or EBR. METHODS The authors performed a retrospective review of pediatric patients treated for craniopharyngioma between 1997 and 2004. This was the time period during which the authors' institution had a relatively high use of P32 for treatment of cystic craniopharyngioma. All patients who had surgery and injection of P32 without EBR were identified. The patient records were analyzed for complications, cyst control, need for further surgery, and need for future EBR. RESULTS Thirty-eight patients were treated for craniopharyngioma during the study period. Nine patients (23.7%) were identified who had surgery (resection or biopsy) with P32 brachytherapy but without initial EBR. These 9 patients represented the study group. For 1 patient (11.1%), there was a complication with the brachytherapy procedure. Five patients (55.5%) required subsequent surgery. Seven patients (77.7%) required subsequent EBR for tumor growth. The mean time between the injection of P32 and subsequent treatment was 1.67 ± 1.50 years (mean ± SD). CONCLUSIONS In this small but focused population, P32 treatment provided limited local control for cyst growth. Brachytherapy alone did not reliably avert the need for subsequent surgery or EBR.

Choroid plexus of the fourth ventricle: Review and anatomic study highlighting anatomical variations.

Relatively few studies have been performed that analyze the morphology of the choroid plexus of the fourth ventricle. Due to the importance of this tissue as a landmark on imaging and during surgical intervention of the fourth ventricle, the authors performed a cadaveric study to better characterize this important structure. The choroid plexus of the fourth ventricle of 60 formalin fixed adult human brains was examined and measured. The horizontal distance from the midline to the lateral most point of the protruding tip of the horizontal limbs was measured. In the majority of the 60 brain specimens, right and left horizontal limbs of the choroid plexus were seen extending from the midline and protruding out of their respective lateral apertures of the fourth ventricle and into the subarachnoid space. However, on 3.3% of sides, there was absence of an extension into the foramen of Luschka and in one specimen, this lack of extension into the foramen of Luschka was bilateral. On two sides, there was discontinuity between the midline choroid plexus and the tuft of choroid just outside the foramen of Luschka. For specimens in which the choroid plexus did protrude through the foramen of Luschka (96.7%), these tufts were located anterior to the flocculus and inferolateral to the facial/vestibulocochlear nerve complex and posterosuperior to the glossopharyngeal/vagal/accessory complex. A thorough understanding of the normal and variant anatomy of the fourth ventricular choroid plexus is necessary for those who operate in, or interpret imaging of, this region.

Feasibility of CT-based intraoperative 3D stereotactic image-guided navigation in the upper cervical spine of children 10 years of age or younger: initial experience.

OBJECT Rigid screw fixation may be technically difficult in the upper cervical spine of young children. Intraoperative stereotactic navigation may potentially assist a surgeon in precise placement of screws in anatomically challenging locations. Navigation may also assist in defining abnormal anatomy. The object of this study was to evaluate the authors' initial experience with the feasibility and accuracy of this technique, both for resection and for screw placement in the upper cervical spine in younger children. METHODS Eight consecutive pediatric patients 10 years of age or younger underwent upper cervical spine surgery aided by image-guided navigation. The demographic, surgical, and clinical data were recorded. Screw position was evaluated with either an intraoperative or immediately postoperative CT scan. RESULTS One patient underwent navigation purely for guidance of bony resection. A total of 14 navigated screws were placed in the other 7 patients, including 5 C-2 pedicle screws. All 14 screws were properly positioned, defined as the screw completely contained within the cortical bone in the expected trajectory. There were no immediate complications associated with navigation. CONCLUSIONS Image-guided navigation is feasible within the pediatric cervical spine and may be a useful surgical tool for placing screws in a patient with small, often difficult bony anatomy. The authors describe their experience with their first 8 pediatric patients who underwent navigation in cervical spine surgery. The authors highlight differences in technique compared with similar navigation in adults.

Dorsal midline hemivertebra at the lumbosacral junction: report of 2 cases.

Congenital scoliosis from laterally located hemivertebrae at the lumbosacral junction has been described previously. However, dorsally located midline hemivertebrae at this location have not been reported. The authors describe the presentation, treatment, and outcomes of 2 patients (1 male and 1 female) with this rare malformation. All clinical and radiographic records were reviewed. Outcomes were recorded using survey instruments (Oswestry Disability Index and the 36-Item Short Form Health Survey). Radiographic assessment of bony fusion was performed using CT scanning 1 year after surgery. Both patients presented with back and leg pain, urinary hesitancy/incontinence, difficulty sitting and lying down, waddling gait, and restriction of movement. Imaging showed a wedge-shaped dorsal deformity that stretched the nerve roots and compressed the canal. Both patients underwent resection of the hemivertebra with posterolateral instrumented fusion from L-2 to the pelvis. The female patient had a low-lying conus and underwent sectioning of the filum terminale. Both patients showed improvement in the ability to sit and lie flat and in bowel and bladder function after surgery. The authors describe their experience with 2 patients with similar, rare congenital bony deformities at the lumbosacral junction. To their knowledge, similar cases have not been previously reported.

The extended supracerebellar transtentorial approach for resection of medial tentorial meningiomas.

BACKGROUND: The supracerebellar transtentorial (SCTT) approach has been established as a safe corridor to access the posteriomedial basal temporal region. Previous reports have demonstrated the efficacy of this route in the resection of intrinsic tumors and small arteriovenous malformations. Only one report in the English literature has described its use to resect a medial tentorial meningioma. METHODS: The authors discuss the relevant surgical anatomy of this approach and its advantages compared with more traditional routes, and illustrate its application to remove medial tentorial meningiomas through two operative cases with accompanying videos. RESULTS: In illustrative case one, the patient recovered from surgery with no deficits. All his preoperative symptoms had resolved at 3-month follow-up. At the 4-year follow-up, MRI did not demonstrate any growth of the residual tumor. In case two, gross total resection was achieved and the patient did not suffer any postoperative language or visual deficit. At 2-year follow-up, no tumor recurrence was present. CONCLUSION: The SCTT approach has a potential to safely access extra-axial lesions located around the medial tentorial incisura. As demonstrated in these two cases, the approach merits consideration in patients with tentorial meningiomas as an alternative to more widely utilized skull base approaches and subtemporal routes.

An analysis of 88 patients with diffuse and "benign" perimesencephalic subarachnoid hemorrhage.

BACKGROUND AND STUDY AIMS: Perimesencephalic subarachnoid hemorrhage (PMSAH) was previously defined as a variant of subarachnoid hemorrhage (SAH) associated with a relatively benign clinical presentation and better outcomes than aneurysmal SAH. However, several prior studies have shown complications associated with PMSAH including vasospasm and hydrocephalus, and the need for follow-up imaging. We therefore reviewed our experience to further characterize the clinical consequences of PMSAH. MATERIALS AND METHODS: Eighty-eight consecutive patients who sustained spontaneous intracranial SAH and whose cerebral angiograms did not show any obvious source for SAH were retrospectively studied to characterize their prognosis and outcome based on SAH pattern. Glasgow Coma Scale and Hunt-Hess scores on admission, the incidence of vasospasm or hydrocephalus, the need for an external ventricular drain, and shunt dependence, along with Glasgow outcome score (GOS) at discharge and follow-up, were used to draw comparisons between perimesencephalic and diffuse SAH patient populations. RESULTS: Patients with perimesencephalic SAH differed statistically (p < 0.05) from patients with diffuse SAH in regard to age, Hunt-Hess score on presentation, hospital length of stay, GOS at discharge, and incidence of hydrocephalus, angiographic vasospasm, and clinical vasospasm. CONCLUSION: Our data demonstrate that although the patients with perimesencephalic SAH fared better than those with diffuse SAH, their outcomes were worse than those of similar patients with PMSAH who have been previously reported in the literature.

Techniques of intraoperative monitoring for spinal cord function: their past, present, and future directions.

PURPOSE: The authors discuss the use of intraoperative monitoring of spinal cord function as an essential part of operations in which the spinal cord is at risk. Although early documented cases of intraoperative monitoring were during operations to correct spinal deformities such as scoliosis, intraoperative monitoring has also increased safety during other operations, such as tumor resection and arteriovenous malformation ablation. METHODS: The authors highlight details involved in monitoring spinal cord function intraoperatively and discuss historical, current, and future perspectives on the use of these monitoring techniques as an essential part of operations in which the spinal cord is at risk. RESULTS: Intraoperative monitoring techniques mitigate the risk of post-operative deficits to the spinal cord by detecting injuries before they become permanent and while they can be reversed. CONCLUSIONS: Intraoperative spinal cord monitoring is safe, cost-effective, and valuable in reducing post-operative sensory and motor deficit. This technique should continue to be refined and its use consistently applied in any procedure where injury to the spinal cord is possible.