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BACKGROUND Primary extraosseous intracranial Ewing’s sarcoma, also known as a peripheral primitive neuroectodermal tumor or “small round blue cell tumor,” is an extremely rare entity with limited representation in the literature beyond the pediatric population. OBSERVATIONS A 67-year-old male suffering occipital headache, nausea, and gait disturbance was found to have a large, avidly contrast-enhancing cerebellopontine angle mass extending into the cervical spinal canal with associated mass effect on medulla, cerebellum, fourth ventricle, and cervical spinal cord. This mass was not present on the imaging from 8 years prior. He underwent surgical debulking and pathology results demonstrated a malignant small round cell tumor showing diffuse immunopositivity for cytokeratins, CD99 and NKX2.2 with EWRS1-FLI1 rearrangement in 84% of the nuclei confirmatory of Ewing’s sarcoma. After 14 cycles of chemotherapy and 6 weeks of radiotherapy, 22 months after discovery, the patient remains in clinical and radiographic remission with complete return to his baseline functioning. LESSONS Primary skull base extraosseous Ewing’s sarcoma should be considered in the differential diagnosis even in the elderly population when imaging studies demonstrate aggressive tumor growth patterns. Tumor debulking to establish a diagnosis followed by adjuvant chemoradiation therapy can result in clinical improvement with remission.

Oculomotor nerve palsies are typically associated with posterior communicating artery (PcommA) aneurysms. We report a rare case of an oculomotor nerve palsy caused by a PcommA infundibular dilatation. Although there are cases of infundibular dilatations causing cranial nerve palsies, only reports of three involving the PcommA exists. We review these reported cases in the literature and discuss their treatments as well as other non-aneurysmal compressive etiologies that may cause oculomotor nerve palsies. We present the case of a 53-year-old female with transient oculomotor nerve palsy that was initially diagnosed with a PcommA aneurysm. She underwent a craniotomy with plans of microsurgical clipping; however, the dilatation was identified correctly as an infundibulum intraoperatively. The operation was completed as a microvascular decompression and her oculomotor nerve palsy has not returned at the 1-year follow-up. We provide a detailed microsurgical report and video detailing the operative technique and relevant anatomy for this operation. Although rare and not as life-threatening as aneurysms, infundibular dilatations as a cause of oculomotor nerve palsy should remain as a differential diagnosis. Given the difference in natural history and treatment of these two entities, it is important to diagnose and treat them appropriately. Multimodal imaging such as thin-sliced computed tomography angiogram (CTA) and 3-dimensional (3D) rotational angiography can aid in diagnosis.

Background Granular cell tumors (GCT) are rare soft tissue neoplasms with a nerve sheath origin, most often found in female adult populations. When these tumors arise in the central nervous system, they most commonly appear intradurally in the thoracic or lumbar spine. GCT malignancy rates vary and recurrence rates can be relatively high, thereby necessitating complete resection. Case Description We present an exceedingly rare case of an intradural, extramedullary GCT originating in the anterior cervical spine of a male pediatric patient who presented with progressive neck pain and gait instability. Conclusions The patient underwent an anterior C7 corpectomy for resection of the tumor, followed by stabilization and fusion, and recovered without neurologic deficit. A literature review of spinal GCTs is provided.

Occipitocervical fusion (OCF) is used to treat several conditions that may cause instability and neurologic compromise at the craniovertebral junction. Craniocervical instability can present with a range of signs and symptoms of myelopathy, lower cranial nerve deficits, and even headaches. There are several radiographic methods that can be utilized to assess for instability at the craniocervical junction. OCF can be accomplished using a variety of instrumentation techniques and bone grafts. The anatomy of the craniocervical junction, radiographic assessment, fusion techniques, postoperative management, and complications avoidance are reviewed in this chapter.

A 30-year-old nulliparous woman at 38 5/7 weeks of gestation developed a sudden, severe headache at work and subsequent loss of consciousness. She underwent evaluation in the emergency department. CT and CT angiogram head revealed a large intraparenchymal haematoma with intraventricular extension secondary to ruptured cerebral arteriovenous malformation (cAVM). She was intubated and transferred to a tertiary care centre. The patient underwent caesarean section followed by partial embolisation of the cAVM with planned second embolisation and resection 1 week later. Due to drowsiness and headache, the planned repeat embolisation and cAVM resection were performed 3 days earlier. The patient had a full recovery. Emergency medicine physicians and obstetrician-gynaecologists should be familiar with differential diagnosis of sudden headache in pregnancy and signs of a ruptured cAVM to facilitate early diagnosis, multidisciplinary team approach and timely treatment. Early diagnosis and management of ruptured cAVM are important due to associated morbidity and mortality.

Trigeminal neuralgia (TN) is characterized by jolts of pain along the distribution of the trigeminal nerve. If patients fail conservative management, microvascular decompression (MVD) is the next step in treatment. MVD is largely done by placing implant pads between the nerve and compressing vessels. We conducted a literature review to assess effectiveness and safety of Teflon™ and Ivalon® sponges for treatment of TN with MVD. In January 2019, PubMed was searched for manuscripts published in English using permutations of “Microvascular decompression”, “Teflon”, “Ivalon”, “Granuloma”, “Polytetrafluoroethylene”, “Trigeminal Neuralgia”, and “Exploration”. Success and relapse rates, causes of relapse, and complication rates were analyzed. We analyzed for relationships with ANCOVA at an alpha threshold of .05. Thirty-six studies representing 4273 patients fit inclusion criteria. Twenty-five dealt with initial MVD, 12 with re-do MVD. Initial MVD initial success rates were 85% in patients receiving Teflon™ (57–100%*) and 91% in patients receiving Ivalon® (79–100%*). Recurrence rates were 12% in Teflon™ patients (0*–30%) and 9.1% in Ivalon® patients (0*–19%). In patients with relapses, implants were the cause in 49% of Teflon™ patients (0*–100%*) and 50% of Ivalon® patients (0*–100%*). Complication rates for patients receiving Teflon™ were 12% (0*–34%) and 19% for patients receiving Ivalon® (0*–40%). Teflon™ and Ivalon® are two materials used in MVD for TN. It is an effective treatment with long-term symptom relief and recurrence rates of 1–5% each year. Ivalon® has been used less than Teflon™ though is associated with similar success rates and similar complication rates.

This operative video demonstrates a C1 lateral mass instrumentation technique that is an alternative to the traditional Goel and Harms techniques.1,2 The advantages of the alternative technique include minimized blood loss from the rich venous plexus surrounding the C2 dorsal root ganglia (DRG), avoidance and preservation of the C2 DRG, and placement of a robust fully threaded screw without risking neuralgia. These are discussed in detail and presented through a case of atlantoaxial instability. Patient's consent was obtained for creating this surgical video. The patient is a 50-yr-old woman with a 17-yr history of rheumatoid arthritis. She presented with 1 yr of neck pain that failed conservative measures. Flexion-extension radiographs demonstrated an atlantodental index (ADI) that reduced from 7 mm on flexion to 0 mm on extension. The patient underwent a C1-C2 posterior instrumented fusion using the alternative technique of C1 lateral mass instrumentation.2 The steps of this technique are explained in great detail through a microsurgical video. The patient's postoperative course was uneventful. Postoperative radiographs and computed tomography (CT) scan demonstrated reduction of ADI and well-placed instrumentation and fusion construct. Her neck pain was completely resolved by 3 mo following surgical stabilization. In the senior author's experience with placing over 120 C1 lateral mass screws with this alternative technique, there have been no instances of vascular injury, sacrifice of C2 DRG, or instrumentation failure. The alternative technique for placement of C1 lateral mass screw is safe, efficient, and holds certain advantages in comparison to the traditionally described method. Images within the video have been reproduced from AOSpine section of the AO Surgery Reference, www.aosurgery.org, with permission from AO Surgery. Copyright by AOSpine International, Switzerland; and reprinted from World Neurosurgery, 78(1-2), Kang MM et al, C2 Nerve Root Sectioning in Posterior C1-2 Instrumented Fusions, 170-177, Copyright 2012, with permission from Elsevier.

Hemifacial spasm is a cranial nerve compression syndrome caused by impingement on the facial nerve most frequently by the anterior inferior cerebellar artery or the posterior inferior cerebellar artery. It can be treated with microvascular decompression (MVD) to separate the nerve from the offending artery. Rarely, a large-caliber vessel such as a dolichoectatic vertebrobasilar system may be implicated, requiring more than an MVD. One technique involves placing a sling around the offending vessel to decompress the facial nerve. We find our "neck-tie" technique to be unique and present it in this detailed video. A 36-year-old-woman presented with a 3-month history of severe left hemifacial spasm refractory to medical management. Imaging demonstrated compression of the left facial nerve and its root entry zone by a dolichoectatic vertebrobasilar complex and anterior inferior cerebellar artery. A left retrosigmoid craniotomy was performed. A Dacron sling was placed around the offending vertebral artery in a "neck-tie" fashion. This sling was used to displace the vertebral artery off of the facial nerve and the sling was then sutured in its final position to the petrous dura. In addition, MVD was performed around the facial nerve's root entry zone. Following sling placement and MVD, neuromonitoring demonstrated absence of abnormal motor responses. Postoperative course was uneventful, she remained neurologically intact, and she remained free of symptoms at 6 months' follow-up. This video highlights the decision making for selecting the appropriate case of hemifacial spasm for sling decompression, the key technical nuances, and complication avoidance in these challenging cases.