Anatomical Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Endoscopic Endonasal Approach to the Sellar and Parasellar Regions

Introduction Surgery of the sellar and parasellar regions can be challenging due to the complexity of neurovascular relationships. The main goal of this study is to develop an educational resource to help trainees understand the pertinent anatomy and procedural steps of the endoscopic endonasal approaches (EEAs) to the sellar and parasellar regions. Methods Ten formalin-fixed latex-injected specimens were dissected. Endoscopic endonasal transsphenoidal transsellar, transtuberculum-transplanum, and transcavernous approaches were performed by a neurosurgery trainee, under supervision from the senior authors and a PhD in anatomy with advanced neuroanatomy experience. Dissections were supplemented with representative case applications. Results Endoscopic endonasal transsphenoidal approaches afford excellent direct access to sellar and parasellar regions. After a wide sphenoidotomy, a limited sellar osteotomy opens the space to sellar region and medial portion of the cavernous sinus. To reach the suprasellar space (infrachiasmatic and suprachiasmatic corridors), a transplanum-prechiasmatic sulcus-transtuberculum adjunct is needed. The transcavernous approach gains access to the contents of the cavernous sinus and both medial (posterior clinoid and interpeduncular cistern) and lateral structures of the retrosellar region. Conclusion The anatomical understanding and technical skills required to confidently remove skull base lesions with EEAs are traditionally gained after years of specialized training. We comprehensively describe EEAs to sellar and parasellar regions for trainees to build knowledge and improve familiarity with these approaches and facilitate comprehension and learning in both the surgical anatomy laboratory and the operating room

Electrical brain stimulation and continuous behavioral state tracking in ambulatory humans

Objective. Electrical deep brain stimulation (DBS) is an established treatment for patients with drug-resistant epilepsy. Sleep disorders are common in people with epilepsy, and DBS may actually further disturb normal sleep patterns and sleep quality. Novel implantable devices capable of DBS and streaming of continuous intracranial electroencephalography (iEEG) signals enable detailed assessments of therapy efficacy and tracking of sleep related comorbidities. Here, we investigate the feasibility of automated sleep classification using continuous iEEG data recorded from Papez's circuit in four patients with drug resistant mesial temporal lobe epilepsy using an investigational implantable sensing and stimulation device with electrodes implanted in bilateral hippocampus (HPC) and anterior nucleus of thalamus (ANT). Approach. The iEEG recorded from HPC is used to classify sleep during concurrent DBS targeting ANT. Simultaneous polysomnography (PSG) and sensing from HPC were used to train, validate and test an automated classifier for a range of ANT DBS frequencies: no stimulation, 2 Hz, 7 Hz, and high frequency (>100 Hz). Main results. We show that it is possible to build a patient specific automated sleep staging classifier using power in band features extracted from one HPC iEEG sensing channel. The patient specific classifiers performed well under all thalamic DBS frequencies with an average F1-score 0.894, and provided viable classification into awake and major sleep categories, rapid eye movement (REM) and non-REM. We retrospectively analyzed classification performance with gold-standard PSG annotations, and then prospectively deployed the classifier on chronic continuous iEEG data spanning multiple months to characterize sleep patterns in ambulatory patients living in their home environment. Significance. The ability to continuously track behavioral state and fully characterize sleep should prove useful for optimizing DBS for epilepsy and associated sleep, cognitive and mood comorbidities

Thalamic deep brain stimulation modulates cycles of seizure risk in epilepsy

Chronic brain recordings suggest that seizure risk is not uniform, but rather varies systematically relative to daily (circadian) and multiday (multidien) cycles. Here, one human and seven dogs with naturally occurring epilepsy had continuous intracranial EEG (median 298 days) using novel implantable sensing and stimulation devices. Two pet dogs and the human subject received concurrent thalamic deep brain stimulation (DBS) over multiple months. All subjects had circadian and multiday cycles in the rate of interictal epileptiform spikes (IES). There was seizure phase locking to circadian and multiday IES cycles in five and seven out of eight subjects, respectively. Thalamic DBS modified circadian (all 3 subjects) and multiday (analysis limited to the human participant) IES cycles. DBS modified seizure clustering and circadian phase locking in the human subject. Multiscale cycles in brain excitability and seizure risk are features of human and canine epilepsy and are modifiable by thalamic DBS

Medullary Venous Hypertension Secondary to a Petrous Apex Dural Arteriovenous Fistula: A Case Report

Background: Dural arteriovenous fistulae (dAVF) are common intracranial vascular lesions typically becoming symptomatic with cortical venous hypertension and possible hemorrhage. Here, we present a case illustration of a petrous apex dAVF with marked medullary venous hypertension and a unique clinical presentation. Methods: Case report. Results: A 72-year-old female, whose clinical progression was significant for altered mental status and progressive weakness, presented with diplopia, right leg paresis, and ataxia. Magnetic resonance imaging revealed edema involving the medulla. On digital subtraction cerebral angiogram, the patient was found to have a petrous apex dAVF, Cognard type IV. Following treatment with Onyx embolization, her symptoms rapidly improved, with complete resolution of diplopia and drastic improvement of her ataxia. Conclusion: The importance of this case is in the presentation and deterioration of the clinical exam, resembling an acute ischemic event. Further, this case illustrates that dAVF may cause venous hypertension with rapid onset of focal neurologic symptoms not exclusive to cortical locations

Endoscopic and Microscopic Transsphenoidal Surgery of Craniopharyngiomas: A Systematic Review of Surgical Outcomes Over Two Decades

Objective Few studies have compared transsphenoidal endoscopic (TE) and transsphenoidal microscopic (TM) techniques for the treatment of craniopharyngiomas. Design We performed a systematic review of published series. The results were stratified in two time periods from 1995 to 2016. Results A total of 48 articles and 1,186 patients met the inclusion criteria. Overall, 60% of endoscopic cases were supradiaphragmatic, and 76% of microsurgical cases were infradiaphragmatic. Mean tumor size was 3 cm and 2.4 cm in the TE and TM series, respectively ( p = 0.008). Total resection rate was similar (66%) between TE and TM. Considering the surgical outcome for different tumor locations, total resection rate was slightly higher in the TE for supradiaphragmatic lesions (59% versus 42.5%; p = 0.26). Recurrence rate was higher in the endoscopic series (21.7% versus 12%). Mortality and the overall complication rates were similar ( p = 0.84). However, hydrocephalus (7.6%) and cognitive dysfunction (15.8%) were more common in TE, and meningitis (6%) and endocrinologic complications were more common in the TM series. In the past 6 years, the rate of cerebrospinal fluid leak in TE was significantly lower (13%) and was comparable between TE and TM. Conclusion Both techniques appear comparable for infradiaphragmatic lesions; however, TE seems to yield better results for supradiaphragmatic tumors. In conclusion, more complex lesions with difficult locations can be effectively treated with endoscopic surgery

Introduction. Techniques in MRI–Negative Cushing disease

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