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Stimulation sites in the subthalamic nucleus projected onto a mean 3-D atlas of the thalamus and basal ganglia

STN.1

Acta Neurochir (2013) 155:1655–1660

In patients with severe forms of Parkinson’s disease (PD), deep brain stimulation (DBS) commonly targets the subthalamic nucleus (STN). Recently, the mean 3-D Morel-Atlas of the basal ganglia and the thalamus was introduced. It combines information contained in histological data from ten post-mortem brains. We were interested whether the Morel-Atlas is applicable for the visualization of stimulation sites.
Methods
In a consecutive PD patient series, we documented preoperative MRI planning, intraoperative target adjustment based on electrophysiological and neurological testing, and perioperative CT target reconstruction. The localization of the DBS electrodes and the optimal stimulation sites were projected onto the Morel-Atlas.
Results
We included 20 patients (median age 62 years). The active contact had mean coordinates Xlat = ±12.1 mm, Yap = −1.8 mm, Zvert = −3.2 mm. There was a significant difference between the initially planned site and the coordinates of the postoperative active contact site (median 2.2 mm). The stimulation site was, on average, more anterior and more dorsal. The electrode contact used for optimal stimulation was found within the STN of the atlas in 38/40 (95 %) of implantations.
Conclusions
The cluster of stimulation sites in individual patients—as deduced from preoperative MR, intraoperative electrophysiology and neurological testing—showed a high degree of congruence with the atlas. The mean 3D Morel Atlas is thus a useful tool for postoperative target visualization. This represents the first clinical evaluation of the recently created atlas.

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Deep Arteriovenous Malformations in the Basal Ganglia, Thalamus, and Insula: Microsurgical Management, Techniques, and Results

Surgery for Deep AVM-1

Neurosurgery 73:417–429, 2013

Arteriovenous malformations (AVMs) in the basal ganglia, thalamus, and insula are considered inoperable given their depth, eloquence, and limited surgical exposure. Although many neurosurgeons opt for radiosurgery or observation, others have challenged the belief that deep AVMs are inoperable. Further discussion of patient selection, technique, and multimodality management is needed.

OBJECTIVE: To describe and discuss the technical considerations of microsurgical resection for deep-seated AVMs.

METHODS: Patients with deep AVMs who underwent surgery during a 14-year period were reviewed through the use of a prospective AVM registry.

RESULTS: Microsurgery was performed in 48 patients with AVMs in the basal ganglia (n = 10), thalamus (n = 13), or insula (n = 25). The most common Spetzler-Martin grade was III2 (68%). Surgical approaches included transsylvian (67%), transcallosal (19%), and transcortical (15%). Complete resection was achieved in 34 patients (71%), and patients with incomplete resection were treated with radiosurgery. Forty-five patients (94%) were improved or unchanged (mean follow-up, 1.6 years).

CONCLUSION: This experience advances the notion that select deep AVMs may be operable lesions. Patients were highly selected for small size, hemorrhagic presentation, young age, and compactness—factors embodied in the Spetzler-Martin and Supplementary grading systems. Overall, 10 different approaches were used, exploiting direct, transcortical corridors created by hemorrhage or maximizing anatomic corridors through subarachnoid spaces and ventricles that minimize brain transgression. The same cautious attitude exercised in selecting patients for surgery was also exercised in deciding extent of resection, opting for incomplete resection and radiosurgery more than with other AVMs to prioritize neurological outcomes.

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The Mirroring Technique: A Navigation-Based Method for Reconstructing a Symmetrical Orbit and Cranial Vault

Mirroring technique

Neurosurgery 73[ONS Suppl 1]:ons24–ons29, 2013

The reconstruction of orbital structures and the cranial vault curvature can be challenging after trauma or wide resections for tumors. Sophisticated methods have been developed recently, but these are resource- and time-consuming.

OBJECTIVE: We report the mirroring technique, which is an effective and costless application for navigation-guided reconstruction procedures.

METHODS: At the time of the reconstruction, high-resolution images are reloaded while forcing a left-right axial flip. The pointer subsequently enables a virtual 3- dimensional projection of the position of the contralateral normal anatomy.

RESULTS: This method was applied successfully in 2 cases of en plaque sphenoid wing meningiomas with secondary exophthalmia.

CONCLUSION: The mirroring technique represents an accurate method of outlining the contralateral normal anatomy onto the pathological side based on navigation guidance.

KEY WORDS:

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Cerebral microarteriovenous malformations

microAVM

J Neurosurg 119:594–602, 2013

Microarteriovenous malformations (micro-AVMs) are a rare subgroup of brain AVMs characterized by a nidus smaller than 1 cm. The authors’ purpose in this study was to assess the clinical presentation, radiological features, therapeutic management, and outcome of these lesions.

METHODS
All angiography studies performed at the authors’ institution since 2000 for the diagnosis of AVM were retrospectively reviewed. Clinicoradiological findings, therapeutic management, and outcome were evaluated.

RESULTS
Twenty-eight patients had presented with AVMs having a nidus diameter smaller than 1 cm or no clearly identifiable nidus but an early draining vein. All patients, except 2, presented with intracranial hemorrhage, and 12 patients had a focal deficit. Supratentorial hematomas were large (mean volume 25 ml), and in 8 patients hematomas were evacuated urgently. In 6 patients cerebral digital subtraction angiography studies were normal. Magnetic resonance imaging and dynamic MR angiography revealed an AVM in 4 of these 6 patients. Treatment of the AVM consisted of surgery in 16 cases, radiosurgery in 6, and endovascular embolization in 2, and there were no posttreatment deficits. Four patients received no treatment because of their poor condition. The AVM was occluded at the follow-up in all patients treated with surgery or embolization and in 4 of the 6 patients treated with radiosurgery. The Glasgow Outcome Scale (GOS) score was good (GOS 4–5) in 23 patients (82%) and poor (GOS 3–2) in 5 (18%).

CONCLUSIONS
Patients with micro-AVMs generally present with large intracranial hemorrhages and neurological deficits. If the initial angiography is negative, then delayed or superselective angiography is recommended. Magnetic resonance imaging may reveal the existence of these lesions. Surgery is the treatment of choice for superficial micro-AVMs, and radiosurgery or embolization can be considered for deep lesions.

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Cervical spine alignment, sagittal deformity, and clinical implications

cervical malalignement

This paper is a narrative review of normal cervical alignment, methods for quantifying alignment, and how alignment is associated with cervical deformity, myelopathy, and adjacent-segment disease (ASD), with discussions of health-related quality of life (HRQOL).

Popular methods currently used to quantify cervical alignment are discussed including cervical lordosis, sagittal vertical axis, and horizontal gaze with the chin-brow to vertical angle.

Cervical deformity is examined in detail as deformities localized to the cervical spine affect, and are affected by, other parameters of the spine in preserving global sagittal alignment. An evolving trend is defining cervical sagittal alignment.

Evidence from a few recent studies suggests correlations between radiographic parameters in the cervical spine and HRQOL. Analysis of the cervical regional alignment with respect to overall spinal pelvic alignment is critical. The article details mechanisms by which cervical kyphotic deformity potentially leads to ASD and discusses previous studies that suggest how postoperative sagittal malalignment may promote ASD.

Further clinical studies are needed to explore the relationship of cervical malalignment and the development of ASD. Sagittal alignment of the cervical spine may play a substantial role in the development of cervical myelopathy as cervical deformity can lead to spinal cord compression and cord tension. Surgical correction of cervical myelopathy should always take into consideration cervical sagittal alignment, as decompression alone may not decrease cord tension induced by kyphosis. Awareness of the development of postlaminectomy kyphosis is critical as it relates to cervical myelopathy.

The future direction of cervical deformity correction should include a comprehensive approach in assessing global cervicalpelvic relationships. Just as understanding pelvic incidence as it relates to lumbar lordosis was crucial in building our knowledge of thoracolumbar deformities, T-1 incidence and cervical sagittal balance can further our understanding of cervical deformities. Other important parameters that account for the cervical-pelvic relationship are surveyed in detail, and it is recognized that all such parameters need to be validated in studies that correlate HRQOL outcomes following cervical deformity correction.

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Nonsurgical treatment of chronic subdural hematoma with tranexamic acid

SDH

J Neurosurg 119:332–337, 2013

Chronic subdural hematoma (CSDH) is a common condition after head trauma. It can often be successfully treated surgically by inserting a bur hole and draining the liquefied hematoma. However, to the best of the authors’ knowledge, for nonemergency cases not requiring surgery, no reports have indicated the best approach for preventing hematoma enlargement or resolving it completely. The authors hypothesized that hyperfibrinolysis plays a major role in liquefaction of the hematoma. Therefore, they evaluated the ability of an antifibrinolytic drug, tranexamic acid, to completely resolve CSDH compared with bur hole surgery alone.

METHODS
From 2007 to 2011, a total of 21 patients with CSDH seen consecutively at Kuki General Hospital, Japan, were given 750 mg of tranexamic acid orally every day. Patients were identified by a retrospective records review, which collected data on the volume of the hematoma (based on radiographic measurements) and any complications. Follow-up for each patient consisted of CT or MRI every 21 days from diagnosis to resolution of the CSDH.

RESULTS
Of the 21 patients, 3 with early stages of CSDH were treated by bur hole surgery before receiving medical therapy. The median duration of clinical and radiographic follow-up was 58 days (range 28–137 days). Before tranexamic acid therapy was initiated, the median hematoma volume for the 21 patients was 58.5 ml (range 7.5–223.2 ml); for the 18 patients who had not undergone surgery, the median hematoma volume was 55.6 ml (range 7.5–140.5 ml). After therapy, the median volume for all 21 patients was 3.7 ml (range 0–22.1 ml). No hematomas recurred or progressed.

CONCLUSIONS
Chronic subdural hematoma can be treated with tranexamic acid without concomitant surgery. Tranexamic acid might simultaneously inhibit the fibrinolytic and inflammatory (kinin-kallikrein) systems, which might consequently resolve CSDH. This medical therapy could prevent the early stages of CSDH that can occur after head trauma and the recurrence of CSDH after surgery.

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Minimally invasive transforaminal lumbar interbody fusions and fluoroscopy

Minimally invasive transforaminal lumbar interbody fusions and fluoroscopy

Neurosurg Focus 35 (2):E8, 2013

There is an increasing awareness of radiation exposure to surgeons and the lifelong implications of such exposure. One of the main criticisms of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is the amount of ionizing radiation required to perform the procedure. The goal in this study was to develop a protocol that would minimize the fluoroscopy time and radiation exposure needed to perform an MIS TLIF without compromising visualization of the anatomy or efficiency of the procedure.

Methods. A retrospective review of a prospectively collected database was performed to review the development of a low-dose protocol for MIS TLIFs in which a combination of low-dose pulsed fluoroscopy and digital spot images was used. Total fluoroscopy time and radiation dose were reviewed for 50 patients who underwent single-level MIS TLIFs.

Results. Fifty patients underwent single-level MIS TLIFs, resulting in the placement of 200 pedicle screws and 57 interbody spacers. There were 28 women and 22 men with an average age of 58.3 years (range 32–78 years). The mean body mass index was 26.2 kg/m2 (range 17.1–37.6 kg/m2). Indications for surgery included spondylolisthesis (32 patients), degenerative disc disease with radiculopathy (12 patients), and recurrent disc herniation (6 patients). Operative levels included 7 at L3–4, 40 at L4–5, and 3 at L5–S1. The mean operative time was 177 minutes (range 139–241 minutes). The mean fluoroscopic time was 18.72 seconds (range 7–29 seconds). The mean radiation dose was 0.247 mGy*m2 (range 0.06046–0.84054 mGy*m2). No revision surgery was required for any of the patients in this series.

Conclusions. Altering the fluoroscopic technique to low-dose pulse images or digital spot images can dramatically decrease fluoroscopy times and radiation doses in patients undergoing MIS TLIFs, without compromising image quality, accuracy of pedicle screw placement, or efficiency of the procedure.

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Early awareness of cerebrospinal fluid hypovolemia after craniotomy for microsurgical aneurysmal clipping

Early awareness of cerebrospinal fluid hypovolemia after craniotomy for microsurgical aneurysmal clipping

Acta Neurochir (2013) 155:1543–1548

Mild cerebrospinal fluid (CSF) hypovolemia is a well-known clinical entity, but critical CSF hypovolemia that can cause transtentorial herniation is an unusual and rare clinical entity that occurs after craniotomy. We investigated CSF hypovolemia after microsurgical aneurysmal clipping for subarachnoid hemorrhage (SAH).

Method This study included 144 consecutive patients with SAH. Lumbar drainage (LD) was inserted after general anesthesia or postoperatively as a standard perioperative protocol. CSF hypovolemia diagnosis was based on three criteria.

Results Eleven patients (7.6 %) were diagnosed with CSF hypovolemia according to diagnostic criteria in a postoperative range of 0–8 days. In all patients, signs or symptoms of CSF hypovolemia improved within 24 hours by clamping LD and using the Trendelenburg position.

Conclusions As a cause of acute clinical deterioration after aneurysmal clipping, CSF hypovolemia is likely underrecognized, and may actually be misdiagnosed as vasospasm or brain swelling. We should always take the etiology of CSF hypovolemia into consideration, and especially pay attention in patients with pneumocephalus and subdural fluid collection alongside brain sag on computed tomography. These patients are at higher risk developing of pressure gradients between their cranial and spinal compartments, and therefore, brain sagging after LD, than after ventricular drainage. We should be vigilant to strictly manage LD so as not to produce high pressure gradients.

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Emergency Noninvasive Angiography for Acute Intracerebral Hemorrhage

CTA

Am J Neuroradiol 34:1481– 87. 2013

Spontaneous ICH is a devastating condition and is associated with significant mortality in the acute phase due to ongoing hemorrhage and hematoma expansion. A growing body of evidence suggests that there may be considerable utility in performing noninvasive vascular imaging during the acute-to-early phase of ICH.

CTA has become widely available and is sensitive and specific for detecting vascular causes of secondary ICH such as aneurysms, arteriovenous malformations, dural arteriovenous fistulas, intracranial dissections, and neoplasm.

CT venography can also diagnose dural sinus thrombosis presenting as hemorrhagic infarction.

Recent data from stroke populations demonstrate a relatively low risk to patients when contrast is administered in the absence of a known serum creatinine. Detection of acute contrast extravasation within the hematoma (“spot sign”) with CT angiography is predictive of subsequent hematoma expansion and is associated with increased morbidity and mortality.

Risk stratification based on acute CTA can inform and expedite decision-making regarding intensive care unit admission, blood pressure control, correction of coagulopathy, and neurosurgical consultation. Noninvasive vascular imaging should be considered as an important component of the initial diagnostic work-up for patients presenting with acute ICH.

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Combined extradural subtemporal and anterior transpetrosal approach to tumors located in the interpeduncular fossa and the upper clivus

Approach to interpeduncular fossa and upper clivus

Acta Neurochir (2013) 155:1401–1407

Central skull base lesions in the interpeduncular fossa and the upper clival regions can be challenging to access because of their location anterior to the brainstem. We have modified the anterior transpetrosal approach by combination with the extradural subtemporal route to increase the surgical corridor.

Methods Thirty-seven patients underwent surgical treatment via the anterior transpetrosal approach from 2002 to 2012. The combined surgical approach was primarily applied when the tumors arose from the upper clival portion and extended to the interpeduncular fossa. The combined approach was used in seven of these patients, comprising four patients with petroclival meningiomas, one patient with sphenoclival meningiomas, one patient with trigeminal schwannoma, and one patient with an epidermoid cyst extending from the interpeduncular fossa to the prepontine cistern.

Results The combined approach permitted excellent visualization of the interpeduncular fossa in addition to the upper clivus and the lateral aspect of the brain stem. Mobilization of the temporal lobe by the entire epidural dissection of the lateral wall of the cavernous sinus facilitates access via the subtemporal route. The transient symptom of the temporal lobe in the dominant site may be the only drawback for this combined approach, although it may disappear immediately after the surgery.

Conclusion The present approach combines Dolenc’s approach and Kawase’s approach, providing a wide exposure to lesions of the interpeduncular fossa and the clivus.

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Biopsy of the Superficial Cortex: Predictors of Effectiveness and Outcomes

Biopsy of the Superficial Cortex

Neurosurgery 73:224–232, 2013 

Brain biopsies of superficial cortex are performed for diagnosis of neurological diseases, but preoperative predictors of successful diagnosis and risks are lacking.

OBJECTIVE: We evaluated effectiveness and outcomes of superficial cortical biopsies and determined preoperative predictors of diagnosis, outcomes, morbidities, and mortality.

METHODS: A single-institution retrospective analysis of 170 patients who underwent open brain biopsies of superficial cortex was performed. Clinical predictors of effectiveness and outcomes were determined using univariate/multivariate analyses and a system for risk-benefit stratification was created and tested.

RESULTS: Brain biopsies led to successful diagnosis in 122 of 170 (71.8%) and affected management in 97 of 170 (57.1%) cases. Factors increasing the odds of diagnostic pathology included age older than 45 years (odds ratio [OR]: 2.67, 95% confidence interval [CI]: 1.34-5.27, P < .01), previous cancer diagnosis (OR: 3.64, 95% CI: 1.69-7.85, P < .001), focal (OR: 3.90, 95% CI: 1.91-8.00, P< .001) and enhancing (OR: 5.03, 95% CI: 2.41-10.52, P< .001) lesions on magnetic resonance imaging, biopsy of specific lesions on magnetic resonance imaging (OR: 9.34, 95% CI: 4.29-20.33, P < .001), and use of intraoperative navigation (OR: 6.59, 95% CI: 3.04-14.28, P < .001). Brain biopsies led to symptomatic intracranial hemorrhage, seizures, other significant morbidities, and perioperative mortality in 12.4%, 16.2%, 37.1%, and 8% of cases, respectively. Risk of postoperative intracranial hemorrhage was increased by a history of aspirin use (OR: 2.51, 95% CI: 1.23-5.28, P < .05) and age older than 60 years (OR: 2.66, 95% CI: 1.36-5.18, P < .01).

CONCLUSION: Effectiveness and risk of morbidity/mortality can be estimated preoperatively for patients undergoing open brain biopsies of the superficial cortex. Older age and specific imaging characteristics increase the odds of diagnostic biopsy. Conversely, older age and aspirin use increases the risk of postoperative complications.

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Surgical management and outcomes of petroclival meningiomas: a single-center case series of 259 patients

Petroclival meningioma outcomes

Acta Neurochir (2013) 155:1367–1383

Surgical management of petroclival meningiomas is challenging. Various and inconsistent outcome and prognostic factors of the lesions have been evaluated previously. In the present study, the surgical outcome, philosophy, and experience of petroclival meningiomas are detailed based on a large patient series.

Methods A series of 259 patients with petroclival meningiomas (70 males and 189 females) were surgically treated. Clinical charts and radiographs were reviewed. Follow-up results were evaluated.

Results The preoperative Karnofsky Performance Scale (KPS) score was 74.2±10.5. The mean tumor size was 4.3±1.0 cm. The gross total resection (GTR) rate was 52.5 %. During a mean follow-up period of 55.3 months, recurrence/progression (R/P) occurred in 11 patients. The recent KPS score was 78.4±22.7, it improved in 139 (57.2 %) patients and stabilized in 53 (21.8 %) patients, and 201 (82.7 %) patients lived independently. The risk factors affecting the KPS score included (but were not limited to) age≥60, preoperative KPS≤60, and brainstem edema. The adverse factors contributing to R/P-free survival included (but were not limited to) non-total resection and the absence of the subarachnoid space. The R/P-free survival rate was 94.5 % at 5 years and 91.2 % at 9 years. The overall survival rate was 94.7 % at 5 years and 94.7 % at 9 years.

Conclusions Favorable outcomes from petroclival meningiomas could be achieved by microsurgery. Neurological function and quality of life were prioritized, and GTR was attempted. Risk factors should be considered in surgical schemes, and tumor recurrence should be aggressively monitored and treated.

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Outcomes of MITLIF and open TLIF approaches

Short-term and long-term outcomes of minimally invasive and open transforaminal lumbar interbody fusions- is there a difference?

Neurosurg Focus 35 (2):E6, 2013

Previous studies comparing minimally invasive transforaminal lumbar interbody fusion (MITLIF) with open TLIF have demonstrated that MITLIF reduces blood loss and decreases postoperative pain while preserving fusion rates and reducing complications. In this study, the authors wanted to compare outcomes of MITLIF with those of open TLIF to determine whether MITLIF also improves postoperative functional mobility and decreases the usage of pain medication.

Methods. In total, 75 consecutive patients who underwent either single-level open TLIF or MITLIF at the University of California, San Francisco, between 2006 and 2011 were included, and patients were followed up for an average of 5.05 years. Fifty patients underwent MITLIF and 25 underwent open TLIF. Primary outcomes included administration of morphine-equivalent narcotics and functional status on postoperative Day 1. Secondary outcomes included operative characteristics, complications, long-term fusion rates, and visual analog scale (VAS) scores.

Results. No statistically significant differences in age, sex, body mass index (BMI), level of disease, or surgical indication were detected between the open TLIF and MITLIF groups. Similarly, preoperative medication usage did not significantly differ between these groups. Intraoperatively, compared with TLIF, MITLIF resulted in decreased lengths of operation, lower blood loss, and fewer complications (p < 0.05). Total administration of morphine-equivalent pain medication in the hospital also tended to be lower in the MITLIF than in the TLIF group. Functional assessment by physical therapy on postoperative Day 1 demonstrated higher function in the MITLIF patients for transfer-related tasks, ambulatory ability, and distance walked than in the TLIF patients (p < 0.05). This translated to shorter inpatient hospitalizations (6.05 vs 4.8 days for open TLIF vs MITLIF patients, respectively, p = 0.006) and an average cost reduction of $3885 per MITLIF patient. Long-term fusion rates were 92% in the MITLIF group and 100% in the open TLIF group (p = 0.09). Preoperative VAS pain scores were 7.1 for the MITLIF patients and 7.6 for the TLIF patients (p = 0.26). At the last follow-up, the reported VAS pain score was 2.9 in the MITLIF patients and 3.5 in the open TLIF patients, but this difference was not statistically significant (p = 0.25). There was also no statistically significant difference in the degree change in this score (p = 0.44).

Conclusions. The MITLIF approach achieves improved functional mobility, decreases the usage of postoperative pain medication, and significantly reduces cost compared with open TLIF while preserving long-term fusion rates. To the authors’ knowledge, this is the first study comparing the postoperative usage of pain medication between treatments in the postoperative period before discharge.

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Displacement of mammillary bodies by craniopharyngiomas involving the third ventricle

Displacement of mammillary bodies by craniopharyngiomas involving the third ventricle- surgical-MRI correlation and use in topographical diagnosis

J Neurosurg 119:381–405, 2013

Accurate diagnosis of the topographical relationships of craniopharyngiomas (CPs) involving the third ventricle and/or hypothalamus remains a challenging issue that critically influences the prediction of risks associated with their radical surgical removal. This study evaluates the diagnostic accuracy of MRI to define the precise topographical relationships between intraventricular CPs, the third ventricle, and the hypothalamus.

Methods. An extensive retrospective review of well-described CPs reported in the MRI era between 1990 and 2009 yielded 875 lesions largely or wholly involving the third ventricle. Craniopharyngiomas with midsagittal and coronal preoperative and postoperative MRI studies, in addition to detailed descriptions of clinical and surgical findings, were selected from this database (n = 130). The position of the CP and the morphological distortions caused by the tumor on the sella turcica, suprasellar cistern, optic chiasm, pituitary stalk, and third ventricle floor, including the infundibulum, tuber cinereum, and mammillary bodies (MBs), were analyzed on both preoperative and postoperative MRI studies. These changes were correlated with the definitive CP topography and type of third ventricle involvement by the lesion, as confirmed surgically.

Results. The mammillary body angle (MBA) is the angle formed by the intersection of a plane tangential to the base of the MBs and a plane parallel to the floor of the fourth ventricle in midsagittal MRI studies. Measurement of the MBA represented a reliable neuroradiological sign that could be used to discriminate the type of intraventricular involvement by the CP in 83% of cases in this series (n = 109). An acute MBA (< 60°) was indicative of a primary tuberal-intraventricular topography, whereas an obtuse MBA (> 90°) denoted a primary suprasellar CP position, causing either an invagination of the third ventricle (pseudointraventricular lesion) or its invasion (secondarily intraventricular lesion; p < 0.01). A multivariate model including a combination of 5 variables (the MBA, position of the hypothalamus, presence of hydrocephalus, psychiatric symptoms, and patient age) allowed an accurate definition of the CP topography preoperatively in 74%–90% of lesions, depending on the specific type of relationship between the tumor and third ventricle.

Conclusions. The type of mammillary body displacement caused by CPs represents a valuable clue for ascertaining the topographical relationships between these lesions and the third ventricle on preoperative MRI studies. The MBA provides a useful sign to preoperatively differentiate a primary intraventricular CP originating at the infundibulotuberal area from a primary suprasellar CP, which either invaginated or secondarily invaded the third ventricle.

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Anterior temporal lobectomy with amygdalohippocampectomy for mesial temporal sclerosis: predictors of long-term seizure control

Anterior temporal lobectomy with amygdalohippocampectomy

J Neurosurg 119:261–272, 2013

In this paper the authors’ goal was to identify preoperative variables that predict long-term seizure freedom among patients with mesial temporal sclerosis (MTS) after single-stage anterior temporal lobectomy and amygdalohippocampectomy (ATL-AH).

Methods. The authors retrospectively reviewed 116 consecutive patients (66 females, mean age at surgery 40.7 years) with refractory seizures and pathologically confirmed MTS who underwent ATL-AH with at least 2 years of follow-up. All patients underwent preoperative MRI and video-electroencephalography (EEG); 106 patients (91.4%) underwent Wada testing and 107 patients (92.2%) had neuropsychological evaluations. The authors assessed the concordance of these 4 studies (defined as test consistent with the side of eventual surgery) and analyzed the impact of preoperative variables on seizure freedom.

Results. The median follow-up after surgery was 6.7 years (mean 6.9 years). Overall, 103 patients (89%) were seizure free, and 109 patients (94%) had Engel Class I or II outcome. Concordant findings were highest for video- EEG (100%), PET (100%), MRI (99.0%), and Wada testing (90.4%) and lowest for SPECT (84.6%) and neuropsychological testing (82.5%). Using binary logistic regression analysis (seizure free or not) and Cox proportional hazard analysis (seizure-free survival), less disparity in the Wada memory scores between the ipsilateral and contralateral sides was associated with persistent seizures.

Conclusions. Seizure freedom of nearly 90% can be achieved with ATL-AH in properly selected patients with MTS and concordant preoperative studies. The low number of poor outcomes and exclusion of multistage patients limit the statistical power to determine preoperative variables that predict failure. Strong Wada memory lateralization was associated with excellent long-term outcome and adds important localization information to structural and neurophysiological data in predicting outcome after ATL-AH for MTS.

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Neuronavigation in minimally invasive spine surgery

Neuronavigation in minimally invasive spine surgery

Neurosurg Focus 35 (2):E12, 2013

Parallel advancements in image guidance technology and minimal access techniques continue to push the frontiers of minimally invasive spine surgery (MISS). While traditional intraoperative imaging remains widely used, newer platforms, such as 3D-fluoroscopy, cone-beam CT, and intraoperative CT/MRI, have enabled safer, more accurate instrumentation placement with less radiation exposure to the surgeon. The goal of this work is to provide a review of the current uses of advanced image guidance in MISS.

Methods. The authors searched PubMed for relevant articles concerning MISS, with particular attention to the use of image-guidance platforms. Pertinent studies published in English were further compiled and characterized into relevant analyses of MISS of the cervical, thoracic, and lumbosacral regions.

Results. Fifty-two studies were included for review. These describe the use of the iso-C system for 3D navigation during C1–2 transarticular screw placement, the use of endoscopic techniques in the cervical spine, and the role of navigation guidance at the occipital-cervical junction. The authors discuss the evolving literature concerning neuronavigation during pedicle screw placement in the thoracic and lumbar spine in the setting of infection, trauma, and deformity surgery and review the use of image guidance in transsacral approaches.

Conclusions. Refinements in image-guidance technologies and minimal access techniques have converged on spinal pathology, affording patients the ability to undergo safe, accurate operations without the associated morbidities of conventional approaches. While percutaneous transpedicular screw placement is among the most common procedures to benefit from navigation, other areas of spine surgery can benefit from advances in neuronavigation and further growth in the field of image-guided MISS is anticipated.

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Automated intracranial pressure-controlled cerebrospinal fluid external drainage with LiquoGuard®

Automated intracranial pressure-controlled CSF LiquoGuard

Acta Neurochir (2013) 155:1589–1595

LiquoGuard is a new device for intracranial pressure (ICP)-controlled drainage of cerebrospinal fluid (CSF). This present study evaluates the accuracy of ICP measurement via the LiquoGuard device in comparison with Spiegelberg. Thus, we compared data ascertained from simultaneous measurement of ICP using tip-transducer and tip-sensor devices.

Material and Methods A total of 1,764 monitoring hours in 15 patients (range, 52–219 h) were analysed. All patients received an intraventricular Spiegelberg III probe with the drainage catheter connected to the LiquoGuard system. ICP reading of both devices was performed on an hourly basis. Statistical analysis was done by applying Pearson correlation and Wilcoxon-matched pair test (p<0.05).

Results Mean ICP values were 11±5 mmHg (Spiegelberg) and 10±7 mmHg (LiquoGuard); the values measured with both devices correlated well (p=0.001; Pearson correlation =0.349; n=1,764). In two of the 15 patients with slit ventricles, episodes of significant differences in measured values could be observed. Both patients suffering from slit ventricles failed to produce reliable measurement with the external transducer of the LiquoGuard.

Conclusions LiquoGuard is a valuable new device for ICP-controlled CSF drainage. However, LiquoGuard tends to provide misleading results in slit ventricles. Thus, before these drawbacks are further analysed, the authors recommend additional ICP measurement with internal tip-sensor devices to avoid dangerous erroneous interpretation of ICP data.

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Arthroplasty Versus Fusion in Single-Level Cervical Degenerative Disc Disease

Fusion

Spine 2013;38:E1096–E1107

Study Design. A systematic review of randomized controlled trials (RCTs).

Objective. To assess the effects of arthroplasty versus fusion in the treatment of radiculopathy or myelopathy, or both, due to singlelevel cervical degenerative disc disease.

Summary of Background Data. There is ongoing debate about whether fusion or arthroplasty is superior in the treatment of single-level cervical degenerative disc disease. Mainly because the intended advantage of arthroplasty compared with fusion, prevention of symptoms due to adjacent segment degeneration in the long term, is not confirmed yet. Until sufficient long-term results become available, it is important to know whether results of 1 of the 2 treatments are superior to the other in the first 1 to 2 years.

Methods. We searched electronic databases for randomized controlled trials. We included randomized controlled trials that directly compared any type of cervical fusion with any type of cervical arthroplasty, with at least 1 year of follow-up. Study selection was performed independently by 3 review authors, and “risk of bias” assessment and data extraction were independently performed by 2 review authors. In case of missing data, we contacted the study authors or the study sponsor. We assessed the quality of evidence.

Results. Nine studies (2400 participants) were included in this review; 5 of these studies had a low risk of bias. Results for the arthroplasty group were better than the fusion group for all primary comparisons, often statistically significant. For none of the primary outcomes was a clinically relevant difference in effect size shown. Quality of the evidence was low to moderate.

Conclusion. There is low to moderate quality evidence that results are consistently in favor of arthroplasty, often statistically significant. However, differences in effect size were invariably small and not clinically relevant for all primary outcomes.

Level of Evidence: 1

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Accuracy of deep brain stimulation electrode placement using intraoperative computed tomography without microelectrode recording

iCT DBS

J Neurosurg 119:301–306, 2013

In this prospective study the authors’ objective was to evaluate the accuracy of deep brain stimulation (DBS) electrode placement using image guidance for direct anatomical targeting with intraoperative CT.

Methods. Preoperative 3-T MR images were merged with intraoperative CT images for planning. Electrode targets were anatomical, based on the MR images. A skull-mounted NexFrame system was used for electrode placement, and all procedures were performed under general anesthesia. After electrode placement, intraoperative CT images were merged with trajectory planning images to calculate accuracy. Accuracy was assessed by both vector error and deviation off the planned trajectory.

Results. Sixty patients (33 with Parkinson disease, 26 with essential tremor, and 1 with dystonia) underwent the procedure. Patient’s mean age was 64 ± 9.5 years. Over an 18-month period, 119 electrodes were placed (all bilateral, except one). Electrode implant locations were the ventral intermediate nucleus (VIM), globus pallidus internus (GPI), and subthalamic nucleus (STN) in 25, 23, and 12 patients, respectively. Target accuracy measurements were as follows: mean vector error 1.59 ± 1.11 mm and mean deviation off trajectory 1.24 ± 0.87 mm. There was no statistically significant difference between the accuracy of left and right brain electrodes. There was a statistically significant (negative) correlation between the distance of the closest approach of the electrode trajectory to the ventricular wall of the lateral ventricle and vector error (r2 = -0.339, p < 0.05, n = 76), and the deviation from the planned trajectory (r2 = -0.325, p < 0.05, n = 77). Furthermore, when the distance from the electrode trajectory and the ventricular wall was < 4 mm, the correlation of the ventricular distance to the deviation from the planned trajectory was stronger (r2 = -0.419, p = 0.05, n = 19). Electrodes placed in the GPI were significantly more accurate than those placed in the VIM (p < 0.05). Only 1 of 119 electrodes required intraoperative replacement due to a vector error > 3 mm. In this series there was one infection and no intraparenchymal hemorrhages.

Conclusions. Placement of DBS electrodes using an intraoperative CT scanner and the NexFrame achieves an accuracy that is at least comparable to other methods.

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Pathology of Spinal Ependymomas

Pathology of Spinal Ependymomas

Neurosurgery 73:247–255, 2013

Ependymomas constitute approximately 40% of primary intraspinal tumors. Current World Health Organization (WHO) grading may not correlate with observed progression-free survival (PFS).

OBJECTIVE: This retrospective study of prospectively collected data examines whether PFS is influenced by the histological grade or by the extent of resection. It also analyzes the usage and effectiveness of postoperative adjuvant radiotherapy.

METHODS: We reviewed 134 consecutive patients with ependymomas of all grades. Pathology slides were re-reviewed and the histological grades were confirmed by a single neuropathologist. Postoperative residual or recurrence was evaluated with follow-up magnetic resonance imaging.

RESULTS: There were 85 male and 49 female patients, ranging from 10 to 79 (median 41) years of age. Thirty patients had WHO grade I tumors, 101 had grade II tumors, and 3 had grade III tumors. Kaplan-Meier analysis of PFS demonstrated a mean duration of 6 years for grade I, 14.9 years for grade II, and 3.7 years for grade III (P , .001). In grade II ependymomas, mean PFS was 11.2 years with subtotal resection and 17.8 years with gross total resection (P, .01). PFS of patients who underwent subtotal resection was not significantly changed by adjuvant radiotherapy (P , .36).

CONCLUSION: Patients with grade II ependymoma have significantly longer PFS than patients with grade I ependymoma. The extent of resection did not affect PFS in grade I ependymoma but it did in grade II. Contrary to its higher grade, WHO grade II ependymoma carries a better prognosis than WHO grade I ependymoma.

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