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Mathias Kunz, Philipp Karschnia, Ingo Borggraefe, Soheyl Noachtar, Joerg-Christian Tonn, and Christian Vollmar

OBJECTIVE

Reoperation may be an option for select patients with unsatisfactory seizure control after their first epilepsy surgery. The aim of this study was to describe the seizure-free outcome and safety of repeated epilepsy surgery in our tertiary referral center.

METHODS

Thirty-eight patients with focal refractory epilepsy, who underwent repeated epilepsy surgeries and had a minimum follow-up time of 12 months after reoperation, were included. Systematic reevaluation, including comprehensive neuroimaging and noninvasive (n = 38) and invasive (n = 25, 66%) video-electroencephalography monitoring, was performed. Multimodal 3D resection maps were created for individual patients to allow personalized reoperation.

RESULTS

The median time between the first operation and reoperation was 74 months (range 5–324 months). The median age at reoperation was 34 years (range 1–74 years), and the median follow-up was 38 months (range 13–142 months). Repeat MRI after the first epilepsy surgery showed an epileptogenic lesion in 24 patients (63%). The reoperation was temporal in 18 patients (47%), extratemporal in 9 (24%), and multilobar in 11 (29%). The reoperation was left hemispheric in 24 patients (63%), close to eloquent cortex in 19 (50%), and distant from the initial resection in 8 (21%). Following reoperation, 27 patients (71%) became seizure free (Engel class I), while 11 (29%) continued to have seizures. There were trends toward better outcome in temporal lobe epilepsy and for unilobar resections adjacent to the initial surgery, but there was no difference between MRI lesional and nonlesional patients. In all subgroups, Engel class I outcome was at least 50%. Perioperative complications occurred in 4 patients (11%), with no fatalities.

CONCLUSIONS

Reoperation for refractory focal epilepsy is an effective and safe option in patients with persistent or recurrent seizures after initial epilepsy surgery. A thorough presurgical reevaluation is essential for favorable outcome.

Open access

Saksham Gupta, Wenya Linda Bi, Donald J. Annino, and Ian F. Dunn

BACKGROUND

Olfactory neuroblastomas are rare sinonasal tumors that arise from the olfactory epithelium. The authors presented a case of an olfactory neuroblastoma with extensive cranial invasion that demonstrated dramatic response to sorafenib, a tyrosine kinase inhibitor.

OBSERVATIONS

A 54-year-old man with history of prostate cancer and melanoma presented with left-sided proptosis and was found to have a 6.5-cm Kadish stage D olfactory neuroblastoma with cranial invasion that was refractory to chemotherapy and everolimus. However, it demonstrated dramatic response to sorafenib, causing extensive skull base defects that prompted operative repair. Genomic analysis of the tumor revealed mutations in TSC1 and SUFU. The patient developed disease progression with liver metastases 35 months after starting sorafenib, prompting a change to lenvatinib. He experienced progression of his olfactory neuroblastoma 10 months following this change and died in hospice 1 month later.

LESSONS

The authors reviewed the clinical presentation and management of a large olfactory neuroblastoma with dramatic response to sorafenib. They highlighted prior uses of targeted therapy in the management of refractory olfactory neuroblastoma within the context of current standard treatment regimens. Targeted therapies may play a vital role in the management of refractory olfactory neuroblastoma.

Open access

Annie Tonnu, Rachel Hunt, Thomas Zervos, Travis Hamilton, Christina Tyrrell, and Adam M. Robin

BACKGROUND

Hypertrophic olivary degeneration (HOD) is a rare condition that can occur after disruption of the Guillain-Mollaret triangle. Clinically, HOD can present with palatal myoclonus with or without oculopalatal tremor, which sometimes results in symptomatic dysphagia and/or speech abnormalities. This condition is commonly associated with vascular lesions, with only three prior reported cases of HOD resulting from intracranial abscess.

OBSERVATIONS

An otherwise healthy patient developed multiple intracranial abscesses. Biopsy showed gram-positive cocci; however, culture findings were negative. Polymerase chain reaction (PCR) identified Streptococcus intermedius. The patient demonstrated palatal myoclonus and vertical nystagmus, which resulted in persistent mild dysphagia and altered speech intonation. After appropriate antimicrobial therapy with resolution of the enhancing lesions, symptoms persisted. Follow-up imaging demonstrated progressive hypertrophy of the right olive with persistent disruption of the right-sided rubro-olivo fiber pathways.

LESSONS

Although HOD classically occurs after vascular insult, it can also be seen as a postinfectious sequela. Despite eradication of the infection, palatal myoclonus and oculopalatal tremor may have a persistent impact on quality of life due to impaired speech and swallowing. This case emphasizes the utility of universal PCR in detecting fastidious organisms as well as diffusion tensor imaging for characterization of disrupted fiber pathways.

Open access

Ellen Collée, Djaina Satoer, Barbara Wegener Sleeswijk, Markus Klimek, Marion Smits, Marie-Lise Van Veelen, Clemens Dirven, and Arnaud Vincent

BACKGROUND

Although the standard procedure to treat adult patients with lesions in eloquent brain areas is awake craniotomy with direct electrical stimulation, this procedure is not often used in children because of feasibility concerns. Some studies have shown that the procedure is feasible in children. They reported the postoperative language ability, which was not based on standardized language tests for children. To give an objective overview of preoperative assessment of the language ability of a child before and after this procedure, the authors described the perioperative course, including standardized language tests for children and the awake surgery setting, of a 12-year-old child undergoing awake craniotomy with brain mapping for the indication of cavernoma in the left somatosensory cortex close to the motor cortex.

OBSERVATIONS

The patient performed better on language tests after surgery, showing that his language ability improved. He also cooperated well during the entire perioperative period. His mother was present during the awake surgery, and the patient tolerated the surgery well.

LESSONS

The authors conclude that awake craniotomy is indeed feasible in a child and that it can even result in an improved postoperative language outcome. It is, however, crucial to carefully assess, inform, and monitor the child and their proxies.

Open access

Natsumi Baba, Ryo Horiuchi, Takashi Yagi, Kazuya Kanemaru, Hideyuki Yoshioka, and Hiroyuki Kinouchi

BACKGROUND

Spinal glomus arteriovenous malformations (AVMs) are rare and can cause neurological morbidity due to spinal hemorrhage, venous hypertension, or mass effect.

OBSERVATIONS

The authors presented a rare case of spinal glomus AVM presenting with groin pain due to nerve root compression by a feeder aneurysm. A 41-year-old woman was referred to the hospital with initial right groin pain that had worsened over 2 months. Magnetic resonance imaging showed intra- and extramedullary abnormal flow voids at the T11–12 level, and spinal angiography revealed an intramedullary AVM, with extramedullary protrusion of an aneurysm on the feeder vessel, which arose from the sulcal artery of the anterior spinal artery. Because compression of the right L1 nerve root by the aneurysm was the likely cause of the patient’s pain, endovascular embolization was performed. The feeder aneurysm disappeared after partial n-butyl 2-cyanoacrylate embolization, and the groin pain disappeared immediately after treatment. Her clinical status has been stable with no recurrence during 1 year of follow-up.

LESSONS

This is the first report of glomus-type AVM presenting with radiculopathy alone. One should not overlook the possibility of spinal AVM among patients with groin pain.

Open access

John T. Kim, Long Di, Arnold B. Etame, Sarah Olson, Michael A. Vogelbaum, and Nam D. Tran

BACKGROUND

Maximal safe resection is the paramount objective in the surgical management of malignant brain tumors. It is facilitated through use of image-guided neuronavigation. Intraoperative image guidance systems use preoperative magnetic resonance imaging (MRI) as the navigational map. The accuracy of neuronavigation is limited by intraoperative brain shift and can become less accurate over the course of the procedure. Intraoperative MRI can compensate for dynamic brain shift but requires significant space and capital investment, often unavailable at many centers.

OBSERVATIONS

The authors described a case in which an image fusion algorithm was used in conjunction with an intraoperative computed tomography (CT) system to compensate for brain shift during resection of a brainstem hemorrhagic melanoma metastasis. Following initial debulking of the hemorrhagic metastasis, intraoperative CT was performed to ascertain extent of resection. An elastic image fusion (EIF) algorithm was used to create virtual MRI relative to both the intraoperative CT scan and preoperative MRI, which facilitated complete resection of the tumor while preserving critical brainstem anatomy.

LESSONS

EIF algorithms can be used with multimodal images (preoperative MRI and intraoperative CT) and create an updated virtual MRI data set to compensate for brain shift in neurosurgery and aid in maximum safe resection of malignant brain tumors.

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Adnan I. Qureshi, Yasemin Akinci, Wei Huang, Muhammad F. Ishfaq, Ameer E. Hassan, Farhan Siddiq, and Camilo R. Gomez

OBJECTIVE

Intravenous (IV) recombinant tissue plasminogen activator (r-tPA) may not provide additional benefit in terms of functional outcomes in patients with acute ischemic stroke (AIS) who undergo endovascular treatment (EVT). In this context, the cost-effectiveness of EVT alone compared with its application following IV r-tPA has not been evaluated.

METHODS

The authors determined the average rates of death or disability in each of the two treatment groups from four randomized clinical trials that enrolled patients with AIS within 4.5 hours of symptom onset and randomly assigned patients to EVT alone and IV r-tPA and EVT. By using three sources derived from previous studies, the authors determined the cost of IV r-tPA, cost of staff time for administration, cost of the EVT, cost of hospital stay, costs of supported discharge and community care, and cost of posthospitalization care and disability. They then assessed the cost-effectiveness of EVT alone using a decision tree for the 1st year after AIS and a Markov model with a 10-year horizon, including probabilistic assessment by Monte Carlo simulations.

RESULTS

The 1-year cost was higher with IV r-tPA and EVT compared with EVT alone (incremental cost ranging between $3554 and $13,788 per patient). The mean incremental cost-effectiveness ratios (ICERs) were −$1589, −$78,327, and −$15,471 per quality-adjusted life-year gained for cost sources 1, 2, and 3, respectively, for EVT alone compared with IV r-tPA and EVT at 10 years. The ceiling ICER (willingness to pay) for a probability of 100% that EVT alone was more cost-effective ranged between $25,000 and $100,000 in the three models.

CONCLUSIONS

EVT alone appears to be more cost-effective compared with EVT and IV r-tPA for the treatment of AIS patients presenting within 4.5 hours of symptom onset.

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Erik B. Vanstrum, Matthew T. Borzage, Joseph Ha, Jason Chu, Meenakshi Upreti, Rex A. Moats, Lillian M. Lai, and Peter A. Chiarelli

OBJECTIVE

Advancements in MRI technology have provided improved ways to acquire imaging data and to more seamlessly incorporate MRI into modern pediatric surgical practice. One such situation is image-guided navigation for pediatric neurosurgical procedures, including intracranial catheter placement. Image-guided surgery (IGS) requires acquisition of CT or MR images, but the former carries the risk of ionizing radiation and the latter is associated with long scan times and often requires pediatric patients to be sedated. The objective of this project was to circumvent the use of CT and standard-sequence MRI in ventricular neuronavigation by investigating the use of fast MR sequences on the basis of 3 criteria: scan duration comparable to that of CT acquisition, visualization of ventricular morphology, and image registration with surface renderings comparable to standard of care. The aim of this work was to report image development, implementation, and results of registration accuracy testing in healthy subjects.

METHODS

The authors formulated 11 candidate MR sequences on the basis of the standard IGS protocol, and various scan parameters were modified, such as k-space readout direction, partial k-space acquisition, sparse sampling of k-space (i.e., compressed sensing), in-plane spatial resolution, and slice thickness. To evaluate registration accuracy, the authors calculated target registration error (TRE). A candidate sequence was selected for further evaluation in 10 healthy subjects.

RESULTS

The authors identified a candidate imaging protocol, termed presurgical imaging with compressed sensing for time optimization (PICO). Acquisition of the PICO protocol takes 25 seconds. The authors demonstrated noninferior TRE for PICO (3.00 ± 0.19 mm) in comparison with the default MRI neuronavigation protocol (3.35 ± 0.20 mm, p = 0.20).

CONCLUSIONS

The developed and tested sequence of this work allowed accurate intraoperative image registration and provided sufficient parenchymal contrast for visualization of ventricular anatomy. Further investigations will evaluate use of the PICO protocol as a substitute for CT and conventional MRI protocols in ventricular neuronavigation.

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Ali Kiapour, Ashutosh Khandha, Elie Massaad, Ian D. Connolly, Muhamed Hadzipasic, Ganesh M. Shankar, Vijay Goel, and John H. Shin

OBJECTIVE

Posterior cervical spine fixation is a robust strategy for stabilizing the spine for a wide range of spinal disorders. With the evolution of spinal implant technology, posterior fixation with lateral mass screws in the subaxial spine is now common. Despite interest in variable rod diameters to meet a wide range of clinical needs such as trauma, revision, and deformity surgery, indications for use of posterior cervical spine fixation are not clear. This laboratory investigation evaluates the mechanical stability and kinematic properties of lateral mass fixation with various commercially available rod diameters.

METHODS

The authors conducted an ex vivo experiment using 13 fresh-frozen human cervical spine specimens, instrumented from C3 to C6 with lateral mass screws, to evaluate the effects of titanium rod diameter on kinematic stability. Each intact spine was tested using a kinematic profiling machine with an optoelectrical camera and infrared sensors applying 1.5-Nm bending moments to the cranial vertebra (C2) simulating flexion-extension, lateral bending, and axial rotation anatomical motions. A compressive follower preload of 150 N was applied in flexion-extension prior to application of a bending moment. Instrumented spines were then tested with rod diameters of 3.5, 4.0, and 4.5 mm. The kinematic data between intact and surgical cases were studied using a nonparametric Wilcoxon signed-rank test. A multivariable, multilevel linear regression model was built to identify the relationship between segmental motion and rod diameter.

RESULTS

Instrumentation resulted in significant reduction in range of motion in all three rod constructs versus intact specimens in flexion-extension, lateral bending, and axial rotation (p < 0.05). The maximum reductions in segmental ROM versus intact spines in 3.5-, 4.0-, and 4.5-mm rod constructs were 61%, 71%, and 81% in flexion-extension; 70%, 76%, and 81% in lateral bending; and 50%, 60%, and 75% in axial rotation, respectively. Segmental motion at the adjacent segments (C2–3 and C6–7) increased significantly (p < 0.05) with increasing rod diameter. The 4.5-mm rod construct had the greatest increase in motion compared to the intact spine.

CONCLUSIONS

With increasing rod diameters from 3.5 to 4.0 mm, flexion-extension, lateral bending, and axial rotation across C3–6 were significantly reduced (p < 0.05). Similar trends were observed with a statistically significant reduction in motion in all anatomical planes when the rod diameter was increased to 4.5 mm. Although the increase in rod diameter resulted in a more rigid construct, it also created an increase (p < 0.05) in the kinematics of the adjacent segments (C2–3 and C6–7). Whether this increase translates into adverse long-term clinical effects in vivo requires further investigation and clinical assessment.

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Nicole E. Hernandez, Victor M. Lu, Nolan Altman, John Ragheb, Toba N. Niazi, and Shelly Wang

OBJECTIVE

MRI is increasingly employed to assess intrauterine fetal anomalies. Central nervous system (CNS) anomalies are common structural conditions that warrant evaluation with fetal MRI and subsequent prenatal consultation with a pediatric neurosurgeon. As the use of fetal MRI increases, there is greater impetus to understand the most common CNS structural anomalies diagnosed in utero, as well as their natural histories.

METHODS

The authors performed a single-center retrospective review of fetal MRI evaluations performed between January 2012 and December 2020. Children who underwent both prenatal and postnatal neurosurgical evaluations of CNS anomalies were included. Specific CNS anomalies on fetal MRI, associated extra-CNS findings, and suspicion for genetic abnormality or syndromes were noted. Postnatal clinical status and interventions were assessed.

RESULTS

Between January 2012 and December 2020, a total of 469 fetal MRI evaluations were performed; of these, 114 maternal-fetal pairs had CNS anomalies that warranted prenatal consultation and postnatal pediatric neurosurgical follow-up. This cohort included 67 male infants (59%), with a mean ± SD follow-up of 29.8 ± 25.0 months after birth. Fetal MRI was performed at 27.3 ± 5.8 weeks of gestational age. The most frequently reported CNS abnormalities were ventriculomegaly (57%), agenesis or thinning of the corpus callosum (33%), Dandy-Walker complex (DWC) (21%), neuronal migration disorders (18%), and abnormalities of the septum pellucidum (17%). Twenty-one children (18%) required neurosurgical intervention at a mean age of 2.4 ± 3.7 months. The most common surgical conditions included myelomeningocele, moderate to severe ventriculomegaly, encephalocele, and arachnoid cyst. Corpus callosum agenesis or thinning was associated with developmental delay (p = 0.02) and systemic anomalies (p = 0.05). The majority of prenatal patients referred for DWC had Dandy-Walker variants that did not require surgical intervention.

CONCLUSIONS

The most common conditions for prenatal neurosurgical assessment were ventriculomegaly, corpus callosum anomaly, and DWC, whereas the most common surgical conditions were myelomeningocele, hydrocephalus, and arachnoid cyst. Only 18% of prenatal neurosurgical consultations resulted in surgical intervention during infancy. The majority of referrals for prenatal mild ventriculomegaly and DWC were not associated with developmental or surgical sequelae. Patients with corpus callosum abnormalities should be concurrently referred to a neurologist for developmental assessments.