The Management of Hydrocephalus in Midline Posterior Fossa Cystic Collections

Neurosurgery 93:576–585, 2023

Hydrocephalus frequently occurs with midline posterior fossa cystic collections. The classification of this heterogeneous group of developmental anomalies, including Dandy–Walker malformation, persisting Blake’s pouch, retrocerebellar arachnoid cysts, and mega cisterna magna, is subject of debate. The absence of diagnostic criteria is confusing regarding the ideal management of PFCC-related hydrocephalus.

OBJECTIVE: To decipher the surgical strategy for the treatment of children with PFCC-related hydrocephalus through a retrospective analysis of the surgical outcome driven by their clinical and radiological presentation.

METHODS: This study enrolled patients operated of symptomatic PFCC-related hydrocephalus. Clinical and MRI features were examined, as well as the surgical outcome. Unbiased subgroup classification of the patients was performed with multiple component analysis as a function of imaging characteristics and hierarchical clustering on principal component. Outcome was assessed with binomial logistic regression and Kaplan–Meier analysis.

RESULTS: Fifty-four patients were included between 2007 and 2021. Multiple component analysis suggested that cerebellar and vermian hypoplasia, vermian rotation, basal–tentorial angle, and fastigial angle were strongly correlated. Hierarchical clustering and the distribution of the patients in the bidimensional plot showed the clear segregation of 3 major clusters, which correlated with the radiological diagnosis (P < .01). Binomial logistic regression and survival analysis showed that endoscopic third ventriculostomy was an effective treatment for patients with persisting Blake’s pouch, while failing to control hydrocephalus in most of patients with Dandy–Walker malformation.

CONCLUSION: Preoperative MRI in patients with PFCC-related hydrocephalus is essential to better define the diagnosis. The choice of treatment strategy notably relies on correct radiological diagnosis.

Risk Factors for Adjacent Segment Disease in Short Segment Lumbar Interbody Fusion

Operative Neurosurgery 25:136–141, 2023

Adjacent segment disease (ASD) is a common problem after lumbar spinal fusions. Ways to reduce the rates of ASD are highly sought after to reduce the need for reoperation.

OBJECTIVE: To find predisposing factors of ASD after lumbar interbody fusions, especially in mismatch of pelvic incidence and lumbar lordosis (PI-LL).

METHODS: We conducted a retrospective cohort study of all patients undergoing lumbar interbody fusions of less than 4 levels from June 2015 to July 2020 with at least 1 year of follow-up and in those who had obtained postoperative standing X-rays.

RESULTS: We found 243 patients who fit inclusion and exclusion criteria. Fourteen patients (5.8%) developed ASD, at a median of 24 months. Postoperative lumbar lordosis was significantly higher in the non-ASD cohort (median 46.4°± 1.4°vs 36.9°± 3.6°, P < .001), pelvic tilt was significantly lower in the non-ASD cohort (16.0°± 0.66°vs 20.3°± 2.4°, P = .002), PI-LL mismatch was significantly lower in the non-ASD cohort (5.28°± 1.0°vs 17.1°± 2.0°, P < .001), and age-appropriate PI-LL mismatch was less common in the non-ASD cohort (34 patients [14.8%] vs 13 [92.9%] of patients with high mismatch, P < .001). Using multivariate analysis, greater PI-LL mismatch was predictive of ASD (95% odds ratio CI = 1.393-2.458, P < .001) and age-appropriate PI-LL mismatch was predictive of ASD (95% odds ratio CI = 10.8-970.4, P < .001).

CONCLUSION: Higher PI-LL mismatch, both age-independent and when adjusted for age, after lumbar interbody fusion was predictive for developing ASD. In lumbar degenerative disease, correction of spinopelvic parameters should be a main goal of surgical correction.

Percutaneous Rhizotomy of the Gasserian Ganglion in Patients With Mass Lesion–Associated Trigeminal Neuralgia

Operative Neurosurgery 25:142–149, 2023

Patients with trigeminal neuralgia (TN) secondary to mass lesions are typically treated by directly addressing the underlying pathology. In cases of TN not alleviated by treatment of the pathology, percutaneous balloon compression (PBC) and glycerol rhizotomy (Gly) are simple and effective ways to alleviate pain. However, there is limited literature on the use of these techniques for patients with TN caused by mass lesions.

OBJECTIVE: To describe the use of PBC/Gly to treat mass lesion–related TN.

METHODS: We report a retrospective, single-institution, descriptive case series of patients who presented with TN secondary to tumor or mass-like inflammatory lesion from 1999 to 2021. Patients with primary, idiopathic, or multiple sclerosis–related TN were excluded. Outcomes included Barrow Neurological Institute (BNI) pain intensity and hypesthesia scores, pain persistence, and postoperative complications.

RESULTS: A total of 459 procedures were identified, of which 16 patients met the inclusion criterion (14 PBC and 2 Gly). Of the 15 patients with tumors, 12 had TN pain despite prior tumor-targeted radiation. Short-term (<3 months) BNI pain intensity improvement occurred in 15 (93.8%) patients. The mean follow-up was 54.4 months. Thirteen (81.3%) patients were pain-free (Barrow Neurological Institute pain intensity scale: IIIa–50%; I–25.0%; II–6.3%) for a mean of 23.8 (range 1137) months. Ten patients (62.5%) had pain relief for ≥6 months from first procedure. New facial numbness developed immediately postprocedure in 8 (50%) patients. Transient, partial abducens nerve palsy occurred in 1 patient.

CONCLUSION: PBC/Gly is an effective option for medically refractory TN in patients with mass-associated TN and is a viable option for repeat treatment.

A Case Series of Trigeminal Neuralgia With Pure Venous Compression: Postoperative Outcomes Associated With Intraoperative Venous Transposition Versus Coagulation

Operative Neurosurgery 24:377–382, 2023

Microvascular decompressions (MVDs) are effective open-surgical procedures for trigeminal neuralgia (TN). Intraoperative management of compressive veins may include either venous transposition or coagulation. Although both are generally considered safe,which technique results in optimal postoperative outcomes remains unclear.

OBJECTIVE: To compare postoperative pain and numbness outcomes after an MVD in patients with TN of exclusive venous compression.

METHODS: We retrospectively reviewed all patients with TN who underwent MVDs at our institution from 2007 to 2020. Patients with TN of pure venous compression were identified using MRI imaging, which was subsequently confirmed intraoperatively. Patient demographics, procedural characteristics, and postoperative pain and numbness scores were recorded and compared. Factors associated with pain recurrence were assessed using survival analyses and multivariate regressions.

RESULTS: We identified 181 patients who presented with TN of pure venous compression. Using a multivariate linear regression, adjusted for age, sex, and presence of multiple sclerosis, use of venous transposition vs coagulation was not significantly associated with the Barrow Neurological Institute pain score at final follow-up, although venous transposition was significantly predictive of a worse postoperative Barrow Neurological Institute numbness score (P = .003). Using a Kaplan–Meier survival analysis and a multivariate Cox proportional hazards regression, respectively, venous transposition was significantly associated with faster (P = .01) as well as higher risk for pain recurrence (P = .01).

CONCLUSION: The use of venous coagulation during an MVD is associated with better postoperative pain and numbness outcomes. The results of our study may help inform preoperative patient counseling and surgical management for TN cases that involve pure venous compression.

Idiopathic Ventral Spinal Cord Hernia—A Single-Center Case Series of 11 Patients

Operative Neurosurgery 24:268–275, 2023

Idiopathic spinal cord herniations (ISCH) are rare defects of the ventromedial or mediolateral dura mater with herniation of the spinal cord through the defect with approximately 350 described cases worldwide. Patients usually become symptomatic with motor or sensory neurological deficits and gait disturbances.

OBJECTIVE: To describe characteristic symptoms and clinical findings and to evaluate the postoperative course and outcomes of ISCH. METHODS: We present a single-center data analysis of a case series of 11 consecutive patients who were diagnosed with ISCH and underwent surgery in our department between 2009 and 2021.

RESULTS: All herniations were located in the thoracic spine between T2 and T9. In most cases, gait ataxia and dysesthesia led to further workup and subsequently to the diagnosis of ISCH. A “far-enough” posterior-lateral surgical approach, hemilaminectomy or laminectomy with a transdural approach, was performed under intraoperative neurophysiological monitoring which was followed by adhesiolysis, repositioning of the spinal cord and sealing using a dura patch. After surgery, clinical symptoms improved in 9 of 11 patients (81.8%), while only 1 patient experienced deterioration of symptoms (9.1%) and 1 patient remained equal (9.1%). The median preoperative McCormick grade was 3 (±0.70), while the median postoperative grade was 2 (±0.98) (P = .0047).

CONCLUSION: In our case series of ISCH, we found that in most patients, neurological deficits improved postoperatively. This indicates that surgery in ISCH should not be delayed in symptomatic patients.


Chronic Encapsulated Expanding Hematomas After Stereotactic Radiosurgery for Intracranial Arteriovenous Malformations

Neurosurgery 92:195–204, 2023

Stereotactic radiosurgery (SRS) offers a minimally invasive treatment modality for appropriately selected intracranial arteriovenous malformations (AVMs). Recent reports have described the development of rare, delayed chronic encapsulated expanding hematomas (CEEHs) at the site of an angiographically confirmed obliterated AVM.

OBJECTIVE: To elucidate the incidence, characteristics, and management of CEEH in patients with AVM after SRS.

METHODS: The records of all patients who underwent SRS for an intracranial AVM at 4 institutions participating in the International Radiosurgery Research Foundation between 1987 and 2021 were retrospectively reviewed. Data regarding characteristics of the AVM, SRS treatment parameters, CEEH presentation, management, and outcomes were collected and analyzed.

RESULTS: Among 5430 patients, 15 developed a CEEH at a crude incidence of 0.28%. Nine patients were female, and the mean age was 43 ± 14.6 years. Nine patients underwent surgical evacuation, while 6 were managed conservatively. The median CEEH development latency was 106 months after SRS. The patients were followed for a median of 32 months, and 9 patients improved clinically, while 6 patients remained stable. No intraoperative complications were reported after CEEH resection, although 1 patient recovered from postoperative meningitis requiring intravenous antibiotics.

CONCLUSION: CEEH is a rare, late complication of AVM SRS with an incidence of 0.28% and a median latency of 106 months. In the presence of a delayed and symptomatic expanding hematoma in the bed of an angiographically obliterated AVM, surgical resection resulted in clinical improvement in most patients. Conservative management is possible in asymptomatic patients with stable, small-sized hematomas in deeply seated locations.

Technical Assessment of Microvascular Decompression for Trigeminal Neuralgia Using a 3-Dimensional Exoscope

Operative Neurosurgery 23:374–381, 2022

Detailed anatomic visualization of the root entry zone of the trigeminal nerve is crucial to successfully perform microvascular decompression surgery (MVD) in patients with trigeminal neuralgia.

OBJECTIVE: To determine advantages and disadvantages using a 3-dimensional (3D) exoscope for MVD surgery.

METHODS: A 4K 3D exoscope (ORBEYE) was used by a single surgical team for MVD in a retrospective case series of 8 patients with trigeminal neuralgia in a tertiary center. Clinical and surgical data were collected, and advantages/disadvantages of using the exoscope for MVD were recorded after each surgery. Descriptive statistics were used to summarize the data.

RESULTS: Adequate MVD of the trigeminal nerve root was possible in all patients by exclusively using the exoscope. It offered bright visualization of the cerebellopontine angle and the root entry zone of the trigeminal nerve that was comparable with a binocular operating microscope. The greatest advantages of the exoscope included good optical quality, the pronounced depth of field of the image for all observers, and its superior surgeon ergonomics. Disadvantages were revealed with overexposure at deep surgical sites and the lack of endoscope integration. In 6 patients, facial pain improved significantly after surgery (Barrow Neurological Institute pain intensity score I in 5 and III in 1 patient), whereas it did not in 2 patients (Barrow Neurological Institute score IV and V). No complications occurred.

CONCLUSION: Utilization of a 3D exoscope for MVD is a safe and feasible procedure. Surgeons benefit from better ergonomics, excellent image quality, and an improved experience for observers.

Dura Management Strategies in the Surgical Treatment of Adult Chiari Type I Malformation

Operative Neurosurgery 23:304–311, 2022

Symptomatic Chiari I malformation is treated with suboccipital decompression and C1 laminectomy. However, whether the dura should be opened (durotomy) or enlarged with a graft (duraplasty) remains unclear.

OBJECTIVE: To compare outcomes in adult Chiari I malformation patients treated with duraplasty, durotomy, or without dural opening (“mini-decompression”).

METHODS: A retrospective, multicenter, population-based cohort study was performed of all adult patients surgically treated for a Chiari I malformation at 3 regional neurosurgical centers between 2005 and 2017. Three different dura management strategies were favored by the participating hospitals, with data stratified accordingly. The primary outcome was measured using the Chicago Chiari Outcome Scale (CCOS), dichotomized into favorable (CCOS ≥13) or unfavorable (CCOS ≤12). Propensity score matching was used to adjust for potential confounders in outcome comparisons.

RESULTS: In total, 318 patients were included, of whom 52% were treated with duraplasty, 37% with durotomy, and 11% with mini-decompression. In total, 285 (90%) showed a favorable surgical outcome (CCOS ≥13). Duraplasty was associated with more favorable CCOS and shorter hospital stay compared with durotomy, both in unadjusted (93% vs 84%. P = .018 and 6.0 vs 8.0 days, P < .001) and adjusted analyses (92% vs 84%, P = .044 and 6.0 vs 8.0 days, P < .001). Mini-decompression was excluded from the adjusted analyses because of its small sample size.

CONCLUSION: In this study of adult Chiari I malformation, posterior fossa decompression with duraplasty was associated with more favorable postoperative outcome, as determined by the CCOS, compared with posterior fossa decompression with durotomy alone.

Anatomo‑functional evaluation for management and surgical treatment of insular cavernous malformation: a case series

Acta Neurochirurgica (2022) 164:1675–1684

Insular cavernous malformations (iCMs) are very rare vascular lesions. Their surgical management is chal- lenging, due to their complex functional and vascular relationship. The continuous improvement of intra-operative tools and neuroimaging techniques has progressively enhanced the safety of iCM surgery. Nevertheless, the best surgical approach remains controversial.

Objective To analyze the potential role of an anatomo-functional classification to guide the iCMs’ management.

Methods The study included patients affected by iCMs and referred to the Senior Author (FA). All cases were divided in 2 groups, according to a mainly pial growth pattern (exophytic group) or a subcortical one (endophytic group). Endophytic iCM was further subdivided in 3 subgroups, based on the insular gyri involved. According to this classification, each patient underwent a specific additional neuroimaging investigation and surgical evaluation.

Results A total of 24 patients were included. In the surgical group, trans-sylvian (TS) approach was used in 6 patients with exophytic or Zone I endophytic iCMs. The transcortical (TC) approach with awake monitoring was used in 6 cases of Zone II endophytic vascular lesions. Both TS and trans-intraparietal sulcal (TIS) approach were used for 3 cases of Zone III endophytic iCM. At follow-up, 3 patients were fully recovered from a transient speech impairment while a permanent morbidity was observed in one case.

Conclusions ICMs represent a single entity with peculiar clinical and surgical aspects. The proposed iCM classification focuses on anatomical and functional concerns, aiming to suggest the best pre-operative work-up and the surgical evaluation.

Fields of Forel Brain Stimulation Improves Levodopa-Unresponsive Gait and Balance Disorders in Parkinson’s Disease

Neurosurgery 89:450–459, 2021

Gait and balance disturbance are challenging symptoms in advanced Parkinson’s disease (PD). Anatomic and clinical data suggest that the fields of Forel may be a potential surgical target to treat these symptoms.

OBJECTIVE: To test whether bilateral stimulation centered at the fields of Forel improves levodopa unresponsive freezing of gait (FOG), balance problems, postural instability, and falls in PD.

METHODS: A total of 13 patients with levodopa-unresponsive gait disturbance (Hoehn and Yahr stage ≥3) were included. Patients were evaluated before (on-medication condition) and 1 yr after surgery (on-medication-on-stimulation condition). Motor symptoms and quality of life were assessed with the Unified Parkinson’s Disease Rating scale (UPDRS III) and Quality of Life scale (PDQ-39). Clinical and instrumented analyses assessed gait, balance, postural instability, and falls.

RESULTS: Surgery improved balance by 43% (95% confidence interval [CI]: 21.2-36.4 to 35.2-47.1; P = .0012), reduced FOG by 35% (95% CI: 15.1-20.3 to 8.1-15.3; P = .0021), and the monthly number of falls by 82.2% (95% CI: 2.2-6.9 to −0.2-1.7; P = .0039). Anticipatory postural adjustments, velocity to turn, and postural sway measurements also improved 1 yr after deep brain stimulation (DBS). UPDRS III motor scores were reduced by 27.2% postoperatively (95% CI: 42.6-54.3 to 30.2-40.5; P < .0001). Quality of life improved 27.5% (95% CI: 34.6-48.8 to 22.4-37.9; P = .0100).

CONCLUSION: Our results suggest that DBS of the fields of Forel improved motor symptoms in PD, as well as the FOG, falls, balance, postural instability, and quality of life.