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Prognostic Factors for Satisfaction After Decompression Surgery for Lumbar Spinal Stenosis

Neurosurgery 82:645–651, 2018

Surgical treatment for lumbar spinal stenosis is associated with both short- and long-term benefits with improvements in patient function and pain. Even though most patients are satisfied postoperatively, some studies report that up to onethird of patients are dissatisfied.

OBJECTIVE: To present clinical outcome data and identify prognostic factors related to patient satisfaction 1 yr after posterior decompression surgery for lumbar spinal stenosis.

METHODS: This multicenter register study included 2562 patients. Patients were treated with various types of posterior decompression. Patients with previous spine surgery or concomitant fusion were excluded. Patient satisfaction was analyzed for associations with age, sex, body mass index, smoking status, duration of pain, number of decompressed vertebral levels, comorbidities, and patient-reported outcome measures,which were used to quantify the effect of the surgical intervention.

RESULTS: At 1-yr follow-up, 62.4% of patients were satisfied but 15.1% reported dissatisfaction. The satisfied patients showed significantly greater improvement in all outcome measures compared to the dissatisfied patients. The outcome scores for the dissatisfied patients were relatively unchanged or worse compared to baseline. Association was seen between dissatisfaction, duration of leg pain, smoking status, and patient comorbidities. Patients with good walking capacity at baseline were less prone to be dissatisfied compared to patients with poor walking capacity.

CONCLUSION: This study found smoking, long duration of leg pain, and cancerous and neurological disease to be associated with patient dissatisfaction, whereas good walking capacity at baseline was positively associated with satisfaction after 1 yr.

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“Birdlime” technique using TachoSil tissue sealing sheet soaked with fibrin glue for sutureless vessel transposition in microvascular decompression

J Neurosurg 128:1522–1529, 2018

Microvascular decompression (MVD) is effective for the treatment of trigeminal neuralgia (TN), hemifacial spasm (HFS), and glossopharyngeal neuralgia. The transposition technique is the standard procedure to avoid adhesions and granuloma around the decompression site but is more complex and difficult to perform than the interposition technique. The authors describe a simple and safe MVD transposition procedure they call the “birdlime” technique, which uses a tissue glue–coated collagen sponge soaked with fibrin glue, and the results of this technique.

METHODS The authors retrospectively reviewed the medical charts and radiographic findings of 27 consecutive patients with TN (8 patients) and HFS (19 patients) who, between January 2012 and December 2015, had undergone an MVD transposition procedure utilizing a tissue glue–coated collagen sponge (TachoSil tissue sealing sheet) soaked with fibrin glue (Tisseel 2-component fibrin sealant, vapor heated). Offending arteries among the patients with TN were the superior cerebellar artery (SCA) in 5 patients, the SCA and anterior inferior cerebellar artery (AICA) in 2, and the AICA in 1. Those among the patients with HFS were the vertebral artery (VA) in 3 patients, the VA and AICA in 4, the VA and posterior inferior cerebellar artery (PICA) in 3, the PICA in 4, the AICA in 1, the AICA-PICA in 3, and the PICA and AICA in 1. Operations were performed according to the Jannetta procedure. The offending artery was transposed and fixed to the dura mater of the petrous bone using TachoSil pieces soaked with fibrin glue. Postoperative constructive interference in steady-state MRI was performed to evaluate the change in the position of the offending artery.

RESULTS Transposition of the offending artery was easily and safely performed in all patients. All patients had total remission of symptoms directly after the procedure. No severe complications occurred. The postoperative course was uneventful. No recurrences, adhesions, or dysfunction of the cranial nerves was observed in any of the patients. Postoperative MRI showed that the offending vessels were displaced and fixed in the appropriate position.

CONCLUSIONS The described transposition technique provides an easy and adjustable way to perform MVD safely and effectively. In addition, this transposition and fixation technique is simple and avoids the risk of needle injury close to the cranial nerves and vessels. This simple sutureless technique is recommended for MVD to reduce the risk of intraoperative neurovascular injury.

 

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Circumferential Wall Enhancement on Magnetic Resonance Imaging is Useful to Identify Rupture Site in Patients with Multiple Cerebral Aneurysms

Neurosurgery 82:638–644, 2018

Identification of rupture sites in patients with multiple intracranial aneurysms is largely based on aneurysmsize, location, and shape. Finding circumferential enhancement along the aneurysm wall (CEAW) on magnetic resonance (MR) vessel wall imaging was recently shown to be indicative of ruptured aneurysm.

OBJECTIVE: To investigate the hypothesis that a higher degree of CEAW would identify the site of rupture in patients with multiple aneurysms.

METHODS: We prospectively performed quantitative analysis of CEAW in consecutive patients with both aneurysmal subarachnoid hemorrhage and multiple aneurysms (26 patientswith a total of 62 aneurysms), usingMR vesselwall imaging. Three-dimensional T1-weighted fast spin-echo sequenceswere obtained before and after injection of contrast media, and the wall enhancement index (WEI) was calculated. Aneurysm characteristics (size, location, irregular shape, aspect ratio [neck-to-dome length/neck width], and WEI) were compared between ruptured and unruptured aneurysms. Odds ratios with 95% confidence intervals for ruptures were calculated with conditional univariable logistic regression analysis. Analyses were repeated after adjustment for aneurysm size.

RESULTS: Large aneurysm size, high aspect ratio, WEI (above the median values), and irregular shape were significantly associated with aneurysm rupture. After adjustment for aneurysm size, WEI (adjusted odds ratio: 8.8; 95% confidence interval, 1.1-72.6) as well as irregular shape and aspect ratio showed a strong association with rupture.

CONCLUSION: CEAW is associated with rupture of intracranial aneurysm independent of aneurysm size and patient characteristics. Contrast-enhanced MR vessel wall imaging helps to identify the site of rupture in patients with multiple aneurysms.

 

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Endoscopic Endonasal Transrotundum Middle Fossa Exposure: Technique of Transpterygoid Maxillary Nerve Transposition

World Neurosurg. (2018) 112:131-137

Middle fossa floor access can be challenging. Open skull base approaches have associated morbidity and yield suboptimal working angles around the temporal lobe. Endoscopic endonasal approaches to the middle fossa are poorly described, but provide an improved angle. I hypothesized that the length of the maxillary nerve can be transposed out of the foramen rotundum to provide a path to expose the full width of the middle fossa floor through the anterolateral and anteromedial triangle.

METHODS: Endoscopic endonasal transpterygoid dissections to expose the middle fossa were performed bilaterally on 2 silicone-injected cadaveric heads (4 sides). Transposition of V2 was then performed on all sides, and additional middle fossa exposure was achieved. Highresolution computed tomography imaging was obtained to quantify the extent of exposure. A transzygomatic approach was also performed for comparison.

RESULTS: The maxillary nerve was successfully transposed in each dissection. A periosteal fold was identified to assist in the mobilization of the infraorbital nerve. The average middle fossa exposure achieved without transposition was 50% (of the medial to lateral width). Transposition increased that to 95%. Comparison with the open transzygomatic approach demonstrated superior surgical trajectory (inferior to superior) with the endonasal route.

CONCLUSIONS: Endoscopic endonasal transpterygoid approaches with or without transposition of the maxillary nerve provide a reasonable option for sequentially exposing the entire medial to lateral extent of the anterolateral triangle. It provides an advantageous inferior to superior surgical angle and can be considered for treatment of select middle fossa floor pathology

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Virtual Reality Glasses and “Eye-Hands Blind Technique” for Microsurgical Training in Neurosurgery

World Neurosurg. (2018) 112:126-130

Microsurgical skills and eye-hand coordination need continuous training to be developed and refined. However, well-equipped microsurgical laboratories are not so widespread as their setup is expensive. Herein, we present a novel microsurgical training system that requires a high-resolution personal computer screen, smartphones, and virtual reality glasses.

METHODS: A smartphone placed on a holder at a height of about 15e20 cm from the surgical target field is used as the webcam of the computer. A specific software is used to duplicate the video camera image. The video may be transferred from the computer to another smartphone, which may be connected to virtual reality glasses. –

RESULTS: Using the previously described training model, we progressively performed more and more complex microsurgical exercises. It did not take long to set up our system, thus saving time for the training sessions.

CONCLUSION: Our proposed training model may represent an affordable and efficient system to improve eyehand coordination and dexterity in using not only the operating microscope but also endoscopes and exoscopes

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Median Supraorbital Keyhole Approach for Clipping Ruptured Distal Anterior Cerebral Artery Aneurysm

World Neurosurg. (2018) 112:73-76

The minimally invasive approach to distal anterior cerebral artery (DACA) aneurysms has not gained much acceptance due to difficulties associated with the conventional frontal paramedian approach. The more proximal basal interhemispheric approach, however, necessitates extensive dissection of soft tissues. We describe a novel minimally invasive median supraorbital keyhole craniotomy with a basal interhemispheric approach for clipping a ruptured DACA aneurysm.

METHODS: A 62-year-old patient presented with subarachnoid hemorrhage. Computed tomography angiography revealed a DACA aneurysm. The surgical technique involved a keyhole craniotomy made via an eyebrow incision extending between the supraorbital notches, and flush with the anterior cranial fossa. The dura was opened at the anterior part, the falx was cut, an interhemispheric dissection was carried out, adequate proximal control was obtained, and the aneurysm neck was dissected and clipped. A relevant review of the literature was carried out.

RESULTS: The patient recovered well, with no residual aneurysm or forehead numbness, with good cosmesis. Compared with the previously described “keyhole unilateral interhemispheric” approaches, our technique has less likelihood of encountering bridging veins; easier cisternal cerebrospinal fluid release, making it feasible even in swollen brain; better proximal vascular control; and trajectory toward the neck rather than dome.

CONCLUSION: The median supraorbital keyhole approach is a minimally invasive technique sufficient for clipping most DACA aneurysms, with easier access, better proximal control, and good cosmesis.

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Can patients with symptomatic Tarlov cysts be differentiated from patients with specific low back pain based on comprehensive history taking?

Acta Neurochirurgica (2018) 160:839–844

Tarlov cysts (TCs) are expanded nerve root sheaths that occur near the dorsal root ganglion and result from increased intraspinal hydrostatic pressure. TCs most frequently affect the lumbosacral plexus and therefore may cause specific symptoms such as perineal pain and neurogenic bladder, bowel, and sphincter problems. It has been estimated that 1% of the population has symptomatic Tarlov cysts (STCs). However, STCs appear to be underdiagnosed, with the pain reported by patients commonly attributed to degenerative alterations seen on MRI. The aim of the present study is to investigate the utility of a comprehensive questionnaire for use by physicians in establishing the diagnosis of STCs.

Methods We compared questionnaire responses regarding patient history between 33 patients diagnosed with symptomatic TCs and 42 patients with chronic low back pain and sciatica due to disc problems or degenerative or inflammatory disorders. The diagnosis of STCs was confirmed using nerve conduction studies (NCS) and electromyography (EMG) of the sacral myotomes by an expert neurophysiologist.

Results The questionnaire responses revealed specific differences in perineal symptoms (perineal pain, dyspareunia, coccygodynia), bowel symptoms (constipation, diarrhea), bladder symptoms (hesitation, retention, frequency), and anal sphincter problems (anal pain, mild fecal incontinence). Additionally, sitting, walking, and straining aggravated pain more frequently in STC patients, and STC patients were more often forced to stop working and/or reduce their social activities.

Conclusions Including the above-listed items in the patient history might facilitate differentiation of low back pain and sciatica due to STCs from that due to disc problems or degenerative or inflammatory disorders.

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Is Eighty the New Sixty? Outcomes and Complications after Lumbar Decompression Surgery in Elderly Patients over 80 Years of Age

World Neurosurg. (2018) 112:e555-e560.

An increasing demographic aging of the general population results in a rising incidence of octogenarians and nonagenarians with spine disease. Patients older than 65 years represent the majority of patients with degenerative lumbar spine disease in our daily clinical routine. Surgical treatment is undertaken reluctantly because of an increased rate of comorbidities. We therefore assessed complication rates of lumbar decompression in regard to neurological outcome and medical conditions in patients age 80 years or older in a retrospective singlecenter series.

METHODS: Data for 244 patients (124 female, 120 male; mean age, 83.1  3 years; age range, 80e95 years) who underwent decompressive surgery for lumbar spinal stenosis or disc herniation between April 2007 and February 2016 were assessed retrospectively. Age at surgery, neurologic deficits (preoperative and postoperative), relevant medical comorbidities and previous lumbar decompression, intraoperative and postoperative complications (e.g., surgery-related, medical), duration of surgery, length of hospital stay, and rate of revision surgeries were recorded.

RESULTS: Surgery was performed for lumbar stenosis (184 patients; 75.4%), lumbar disc herniation (13 patients; 5.3%) or both (47 patients; 19.3%). Seventy-six patients (31.3%) patients experienced preoperative neurologic deficits; 48 (63.2%) of these patients improved, 28 (36.8%) of them were unchanged after surgery, and none deteriorated. New transient, postoperative, neurologic deficits occurred in 6 patients (2.5%). All 55 (22.5%) intraoperative complications were mild to moderate, and no severe surgical complications occurred. Two hundred fifteen patients (88%) had relevant medical disorders. Nineteen (7.7%) postoperative medical complications were reported in 17 patients (7%), of which 14 (73.7%) were severe and 5 (26.3%) were mild (4 pulmonary embolisms, 6 pneumonias, 3 myocardial infarctions, 1 postoperative renal failure, 5 urinary tract infections). Medical complications that necessitated intensive care unit treatment and resulted in lethal outcome were seen in 2 patients (0.8%).

CONCLUSION: Despite their age, the vast majority of octogenarians and nonagenarians benefited from lumbar decompression surgery. Mild to moderate intraoperative complications were relatively frequent, whereas severe intraoperative complications did not occur. The majority of medical complications was severe, but the incidence was acceptable, and the postoperative outcome was still favorable in most patients

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Deep brain stimulation for Parkinson’s disease: meta-analysis of results of randomized trials at varying lengths of follow-up

J Neurosurg 128:1199–1213, 2018

Deep brain stimulation (DBS) is effective in the management of patients with advanced Parkinson’s disease (PD). While both the globus pallidus pars interna (GPi) and the subthalamic nucleus (STN) are accepted targets, their relative efficacy in randomized controlled trials (RCTs) has not been established beyond 12 months. The objective of this study was to conduct a meta-analysis of RCTs to compare outcomes among adults with PD undergoing DBS of GPi or STN at various time points, including 36 months of follow-up.

METHODS The MEDLINE, Embase, CENTRAL, Web of Science, and CINAHL databases were searched. Registries for clinical trials, selected conference proceedings, and the table of contents for selected journals were also searched. Screens were conducted independently and in duplicate. Among the 623 studies initially identified (615 through database search, 7 through manual review of bibliographies, and 1 through a repeat screen of literature prior to submission), 19 underwent full-text review; 13 of these were included in the quantitative meta-analysis. Data were extracted independently and in duplicate. The Cochrane Collaboration tool was used to assess the risk of bias. The GRADE evidence profile tool was used to assess the quality of the evidence. Motor scores, medication dosage reduction, activities of daily living, depression, dyskinesias, and adverse events were compared. The influence of disease duration (a priori) and the proportion of male patients within a study (post hoc) were explored as potential subgroups.

RESULTS Thirteen studies (6 original cohorts) were identified. No difference in motor scores or activities of daily living was identified at 36 months. Medications were significantly reduced with STN stimulation (5 studies, weighted mean difference [WMD] -365.46, 95% CI -599.48 to -131.44, p = 0.002). Beck Depression Inventory scores were significantly better with GPi stimulation (3 studies; WMD 2.53, 95% CI 0.99–4.06 p = 0.001). The motor benefits of GPi and STN DBS for PD are similar.

CONCLUSIONS The motor benefits achieved with GPi and STN DBS for PD are similar. DBS of STN allows for a greater reduction of medication, but not as significant an advantage as DBS of GPi with respect to mood. This difference is sustained at 36 months. Further long-term studies are necessary.

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Quality of Life in Patients with Vestibular Schwannomas Following Gross Total or Less than Gross Total Microsurgical Resection: Should We be Taking the Entire Tumor Out?

Neurosurgery 82:541–547, 2018

The goal of microsurgical removal of a vestibular schwannoma is to completely remove the tumor, to provide long-term durable cure. In many cases, less than gross total resection (GTR) is performed to preserve neurological, and especially facial nerve function.

OBJECTIVE: To analyze long-term quality of life (QoL) in a cohort of patients who received either GTR or less than GTR.

METHODS: Patients operated for vestibular schwannoma less than 3.0 cm in posterior fossa diameter at 1 of 2 international tertiary care centers were surveyed using generic and disease-specific QoL instruments.

RESULTS: A total of 143 patients were analyzed. GTR was performed in 122, and 21 underwent less than GTR. QoL was assessed at a mean of 7.7 yr after surgery (interquartile range: 5.7-9.6). Patients who underwent GTR had smaller tumors; otherwise, there were no baseline differences between groups. Patients who underwent GTR, after multivariable adjustment for baseline features and facial nerve and hearing outcomes, reported statistically significantly better Short Form Health Survey-36 (SF-36) physical and mental scores, Patient-Reported Outcomes Measurement Information System (PROMIS-10) physical and mental scores, and Penn Acoustic NeuromaQuality of Life (PANQOL) facial, energy, general health, and total scores compared to patients receiving less than GTR.

CONCLUSION: GTR is associated with better QoL using the general QoL measures SF-36 and PROMIS-10 and the disease-specific PANQOL, even after controlling for baseline and outcome differences. This is especially significant in the assessment of mental health, indicating there may indeed be a psychological advantage to the patient that translates to overall well-being to have the entire tumor removed if microsurgical resection is undertaken.

 

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Subthalamic deep brain stimulation under general anesthesia and neurophysiological guidance while on dopaminergic medication

Acta Neurochirurgica (2018) 160:823–829

The authors have previously reported on the technical feasibility of subthalamic nucleus deep brain stimulation (STN DBS) under general anesthesia (GA) with microelectrode recording (MER) guidance in Parkinsonian patients who continued dopaminergic therapy until surgery. This paper presents the results of a prospective cohort analysis to verify the outcome of the initial study, and report on wider aspects of clinical outcome and postoperative recovery. Methods All patients in the study group continued dopaminergic therapy until GA was administered. Baseline characteristics, intraoperative neurophysiological markers, and perioperative complications were recorded. Long-term outcome was assessed using selective aspects of the unified Parkinson’s disease rating scale motor score. Immediate postoperative recovery from GA was assessed using the Btime needed for extubation^ and Btotal time of recovery.^ Data for the Bstudy group^ was collected prospectively. Examined variables were compared between the Bstudy group^ and Bhistorical control group^ who stopped dopaminergic therapy preoperatively. Results The study group, n = 30 (May 2014–Jan 2016), were slightly younger than the Bcontrol group,^ 60 (51–64) vs. 64 (56– 69) years respectively, p = 0.043. Both groups were comparable for the recorded intraoperative neurophysiological parameters;number of MER tracks: 60% of the study group had single track vs. 58% in the control group, p = 1.0. Length of STN MER detected was 9 vs. 7 mm (median) respectively, p = 0.037. A trend towards better recovery from GA in the study group was noted, with shorter total recovery time: 60 (50–84) vs. 89 (62–120) min, p = 0.09. Long-term improvement in motor scores and reduction in L-dopa daily equivalent dose were equally comparable between both groups. No cases of dopamine withdrawal or problems with immediate postop dyskinesia were recorded in the on medications group. The observed rate of dopamine withdrawal side effects in the off-medications group was 15%.

Conclusions The continuation of dopaminergic treatment for patients with PD does not affect the feasibility/outcome of the STN DBS surgery. This strategy appears to reduce the risk of dopamine-withdrawal adverse effects and may improve the recovery in the immediate postoperative period, which would help enhance patients’ perioperative experience.

 

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Stereoelectroencephalography in insular epilepsy

J Neurosurg 128:1147–1157, 2018

Insular epilepsy is relatively rare; however, exploring the insular cortex when preoperative workup raises the suspicion of insular epilepsy is of paramount importance for accurate localization of the epileptogenic zone and achievement of seizure freedom. The authors review their clinical experience with stereoelectroencephalography (SEEG) electrode implantation in patients with medically intractable epilepsy and suspected insular involvement.

METHODS A total of 198 consecutive cases in which patients underwent SEEG implantation with a total of 1556 electrodes between June 2009 and April 2013 were reviewed. The authors identified patients with suspected insular involvement based on seizure semiology, scalp EEG data, and preoperative imaging (MRI, PET, and SPECT or magnetoencephalography [MEG]). Patients with at least 1 insular electrode based on the postoperative 3D reconstruction of CT fused with the preoperative MRI were included.

RESULTS One hundred thirty-five patients with suspected insular epilepsy underwent insular implantation of a total of 303 electrodes (1–6 insular electrodes per patient) with a total of 562 contacts. Two hundred sixty-eight electrodes (88.5%) were implanted orthogonally through the frontoparietal or temporal operculum (420 contacts). Thirty-five electrodes (11.5%) were implanted by means of an oblique trajectory either through a frontal or a parietal entry point (142 contacts). Nineteen patients (14.07%) had insular electrodes placed bilaterally. Twenty-three patients (17.04% of the insular implantation group and 11.6% of the whole SEEG cohort) were confirmed by SEEG to have ictal onset zones in the insula. None of the patients experienced any intracerebral hemorrhage related to the insular electrodes. After insular resection, 5 patients (33.3%) had Engel Class I outcomes, 6 patients (40%) had Engel Class II, 3 patients (20%) had Engel Class III, and 1 patient (6.66%) had Engel Class IV.

CONCLUSIONS Insula exploration with stereotactically placed depth electrodes is a safe technique. Orthogonal electrodes are implanted when the hypothesis suggests opercular involvement; however, oblique electrodes allow a higher insular sampling rate.

 

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Deep brain stimulation for the early treatment of the minimally conscious state and vegetative state

J Neurosurg 128:1189–1198, 2018

An effective treatment of patients in a minimally conscious state (MCS) or vegetative state (VS) caused by hypoxic encephalopathy or traumatic brain injury (TBI) is not yet available. Deep brain stimulation (DBS) of the thalamic reticular nuclei has been attempted as a therapeutic procedure mainly in patients with TBI. The purpose of this study was to investigate the therapeutic use of DBS for patients in VS or MCS.

METHODS Fourteen of 49 patients in VS or MCS qualified for inclusion in this study and underwent DBS. Of these 14 patients, 4 were in MCS and 10 were in VS. The etiology of VS or MCS was TBI in 4 cases and hypoxic encephalopathy due to cardiac arrest in 10. The selection criteria for DBS, evaluating the status of the cerebral cortex and thalamocortical reticular formation, included: neurological evaluation, electrophysiological evaluation, and the results of positron emission tomography (PET) and MRI examinations. The target for DBS was the centromedian-parafascicular (CM-pf) complex. The duration of follow-up ranged from 38 to 60 months.

RESULTS Two MCS patients regained consciousness and regained their ability to walk, speak fluently, and live independently. One MCS patient reached the level of consciousness, but was still in a wheelchair at the time the article was written. One VS patient (who had suffered a cerebral ischemic lesion) improved to the level of consciousness and currently responds to simple commands. Three VS patients died of respiratory infection, sepsis, or cerebrovascular insult (1 of each). The other 7 patients remained without substantial improvement of consciousness.

CONCLUSIONS Spontaneous recovery from MCS/VS to the level of consciousness with no or minimal need for assistance in everyday life is very rare. Therefore, if a patient in VS or MCS fulfills the selection criteria (presence of somatosensory evoked potentials from upper extremities, motor and brainstem auditory evoked potentials, with cerebral glucose metabolism affected not more than the level of hypometabolism, which is judged using PET), DBS could be a treatment option.

 

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Incidence and clinical relevance of cage subsidence in anterior cervical discectomy and fusion

Acta Neurochirurgica (2018) 160:873–880

The placement of intervertebral cages in anterior cervical discectomy (ACDF) supposedly maintains foraminal height. The most commonly reported cage-related complication is subsidence, although it is unknown whether a correlation between subsidence and clinical outcome exists. Aim To assess the incidence and relevance of subsidence.

Methods Literature searches were performed in PubMed, MEDLINE, Embase,Web of Science, COCHRANE, and CENTRAL. The inclusion criteria were as follows: ≥ 20 patients, ADCF with cage, subsidence assessed, and primary data. Risk of bias was assessed using adjusted Cochrane checklists.

Results Seventy-one studies, comprising 4784 patients, were included. Subsidence was generally defined as ≥ 3-mm loss of height comparing postoperative intervertebral heights with heights at last follow-up. Mean incidence of subsidence was 21% (range 0–83%). Of all patients, 46% of patients received polyether-ether-ketone (PEEK) cages, 31% received titanium cages, 18% received cage-screw-combinations, and 5% received polymethyl-methacrylate (PMMA) cages. Patients treated with cagescrew- combinations had significantly less subsidence than patients treated with PEEK, titanium, or PMMA cages (15.1% vs. 23.5% vs. 24.9% vs. 30.2%; p < 0.001). Thirteen studies assessed clinical outcome in relation to subsidence; the majority did not find a significant correlation. Only four studies correlated subsidence to cage size and/or height; no correlation was established.

Conclusions Subsidence in ACDF with cages occurs in 21% of patients. The risk for subsidence seems lower using PEEK or titanium cages or adding screws.Whether subsidence affects clinical outcome is not satisfactorily evaluated in the available literature. Future studies on this correlation are warranted in order to establish the additional value of the interposition of a cage in ACDF.

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Flow diverter devices in ruptured intracranial aneurysms

J Neurosurg 128:1037–1043, 2018

In this single-center series, the authors retrospectively evaluated the effectiveness, safety, and midterm follow-up results of ruptured aneurysms treated by implantation of a flow diverter device (FDD).

METHODS The records of 17 patients (12 females, 5 males, average World Federation of Neurosurgical Societies score = 2.9) who presented with subarachnoid hemorrhage (SAH) due to the rupture of an intracranial aneurysm treated with an FDD were retrospectively reviewed. Of 17 ruptured aneurysms, 8 were blood blister–like aneurysms and the remaining 9 were dissecting aneurysms. The mean delay between SAH and treatment was 4.2 days. Intraprocedural and periprocedural morbidity and mortality were recorded. Clinical and angiographic follow-up evaluations were conducted between 6 and 12 months after the procedure.

RESULTS None of the ruptured aneurysms re-bled after endovascular treatment. The overall mortality rate was 12% (2/17), involving 2 patients who died after a few days because of complications of SAH. The overall morbidity rate was 12%: 1 patient experienced intraparenchymal bleeding during the repositioning of external ventricular drainage, and 1 patient with a posterior inferior cerebellar artery aneurysm developed paraplegia due to a spinal cord infarction after 2 weeks. The angiographic follow-up evaluations showed a complete occlusion of the aneurysm in 12 of 15 surviving patients; of the 3 remaining cases, 1 patient showed a remnant of the aneurysm, 1 patient was retreated due to an enlargement of the aneurysm, and 1 patient was lost at the angiographic follow-up.

CONCLUSIONS FDDs can be used in patients with ruptured aneurysms, where conventional neurosurgical or endovascular treatments can be challenging.

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Risk factors associated with postoperative cerebrospinal fluid leak after endoscopic endonasal skull base surgery

J Neurosurg 128:1066–1071, 2018

The aim in this paper was to determine risk factors for the development of a postoperative CSF leak after an endoscopic endonasal approach (EEA) for resection of skull base tumors.

METHODS A retrospective review of patients who underwent EEA for the resection of intradural pathology between January 1997 and June 2012 was performed. Basic demographic data were collected, along with patient body mass index (BMI), tumor pathology, reconstruction technique, lumbar drainage, and outcomes.

RESULTS Of the 615 patients studied, 103 developed a postoperative CSF leak (16.7%). Sex and perioperative lumbar drainage did not affect CSF leakage rates. Posterior fossa tumors had the highest rate of CSF leakage (32.6%), followed by anterior skull base lesions (21.0%) and sellar/suprasellar lesions (9.9%) (p < 0.0001). There was a higher leakage rate for overweight and obese patients (BMI > 25 kg/m2) than for those with a healthy-weight BMI (18.7% vs 11.5%; p = 0.04). Patients in whom a pedicled vascularized flap was used for reconstruction had a lower leakage rate than those in whom a free graft was used (13.5% vs 27.8%; p = 0.0015). In patients with a BMI > 25 kg/m2, the use of a pedicled flap reduced the rate of CSF leakage from 29.5% to 15.0% (p = 0.001); in patients of normal weight, this reduction did not reach statistical significance (21.9% [pedicled flap] vs 9.2% [free graft]; p = 0.09).

CONCLUSIONS Preoperative BMI > 25 kg/m2 and tumor location in the posterior fossa were associated with higher rates of postoperative CSF leak. Use of a pedicled vascularized flap may be associated with reduced risk of a CSF leak, particularly in overweight patients.

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Endplate changes after lumbar discectomy with and without implantation of an annular closure device

Acta Neurochirurgica (2018) 160:855–862

The implantation of a bone-anchored annular closure device (ACD) might be associated with the developed new endplate changes (EPC) after surgery.

Methods A post hoc analysis has been done in patients from a prospective randomized multicenter study. All patients underwent limited lumbar discectomy with intraoperative randomization into the groups limited lumbar discectomy alone or additional ACD implantation. Low-dose lumbar computed tomography (CT) and clinical investigations were performed preoperatively and 12 months after the operation.

Results A total of 554 patients were randomized. After exclusion of dropouts, the per-protocol population included 493 patients (251 in the control group and 242 in the ACD group); the follow-up rate was ≥ 90%. The number of patients showing EPC at baseline was similar in both groups. The number of patients showing EPC and the total EPC lesion area significantly increased in both groups over time, but significantly increased more in the EPC group for the superior and inferior endplate (all P < 0.0001). There was no association of pre-existing number and size of EPC with sex, age, or smoking habits. Correlation of clinical variables showed no relation with number, size, and increase of EPC area after surgery.

Conclusions Patients with primary lumbar disc herniation show EPC in the corresponding segments. There is a significant increase of lesion number and size within 12 months after discectomy. This increase is significantly more pronounced in the ACD group. Presence and growth of EPC is not correlated with low-back pain or ODI.

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Management of Odontoid Fractures in the Elderly

Neurosurgery 82:419–430, 2018

Odontoid fractures are the most common fracture of the axis and the most common cervical spine fracture in patients over 65. Despite their frequency, there is considerable ambiguity regarding optimal management strategies for these fractures in the elderly. Poor bone health and medical comorbidities contribute to increased surgical risk in this population; however, nonoperative management is associated with a risk of nonunion or fibrous union.

We provide a review of the existing literature and discuss the classi- fication and evaluation of odontoid fractures. The merits of operative vs nonoperative management, fibrous union, and the choice of operative approach in elderly patients are discussed. A treatment algorithm is presented based on the available literature.

We believe that type I and type III odontoid fractures can be managed in a collar in most cases. Type II fractures with any additonal risk factors for nonunion (displacement, comminution, etc) should be considered for surgical management. However, the risks of surgery in an elderly population must be carefully considered on a case-by-case basis. In a frail elderly patient, a fibrous nonunion with close follow-up is an acceptable outcome. If operative management is chosen, a posterior approach is should be chosen when fracture- or patient-related factors make an anterior approach challenging.

The high levels of morbidity and mortality associated with odontoid fractures should encourage all providers to pursue medical co- management and optimization of bone health following diagnosis.

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Surgical strategy to avoid ischemic complications of the pyramidal tract in resective epilepsy surgery of the insula

J Neurosurg 128:1173–1177, 2018

Surgical treatment of the insula is notorious for its high probability of motor complications, particularly when resecting the superoposterior part. Ischemic damage to the pyramidal tract in the corona radiata has been regarded as the cause of these complications, resulting from occlusion of the perforating arteries to the pyramidal tract through the insular cortex. The authors describe a strategy in which a small piece of gray matter is spared at the bottom of the periinsular sulcus, where the perforating arteries pass en route to the pyramidal tract, in order to avoid these complications.

This method was successfully applied in 3 patients harboring focal cortical dysplasia in the posterior insula and frontoparietal operculum surrounding the periinsular sulcus. None of the patients developed permanent postoperative motor deficits, and seizure control was achieved in all 3 cases.

The method described in this paper can be adopted for functional preservation of the pyramidal tract in the corona radiata when resecting epileptogenic pathologies involving insular and opercular regions.

 

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Revisiting the rules for freehand ventriculostomy: a virtual reality analysis

J Neurosurg 128:1250–1257, 2018

Frontal ventriculostomy is one of the most frequent and standardized procedures in neurosurgery. However, many first and subsequent punctures miss the target, and suboptimal placement or misplacement of the catheter is common. The authors therefore reexamined the landmarks and rules to determine the entry point and trajectory with the best hit rate (HtR).

METHODS The authors randomly selected CT scans from their institution’s DICOM pool that had been obtained in 50 patients with normal ventricular and skull anatomy and without ventricular puncture. Using a 5 × 5–cm frontal grid with 25 entry points referenced to the bregma, the authors examined trajectories 1) perpendicular to the skull, 2) toward classic facial landmarks in the coronal and sagittal planes, and 3) toward an idealized target in the middle of the ipsilateral anterior horn (ILAH). Three-dimensional virtual reality ventriculostomies were simulated for these entry points; trajectories and the HtRs were recorded, resulting in an investigation of 8000 different virtual procedures.

RESULTS The best HtR for the ILAH was 86% for an ideal trajectory, 84% for a landmark trajectory, and 83% for a 90° trajectory, but only at specific entry points. The highest HtRs were found for entry points 3 or 4 cm lateral to the midline, but only in combination with a trajectory toward the contralateral canthus; and 1 or 2 cm lateral to the midline, but only paired with a trajectory toward the nasion. The same “pairing” exists for entry points and trajectories in the sagittal plane. For perpendicular (90°) trajectories, the best entry points were at 3–5 cm lateral to the midline and 3 cm anterior to the bregma, or 4 cm lateral to the midline and 2 cm anterior to the bregma.

CONCLUSIONS Only a few entry points offer a chance of a greater than 80% rate of hitting the ILAH, and then only in combination with a specific trajectory. This “pairing” between entry point and trajectory was found both for landmark targeting and for perpendicular trajectories, with very limited variability. Surprisingly, the ipsilateral medial canthus, a commonly reported landmark, had low HtRs, and should not be recommended as a trajectory target.

 

 

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