Sensory and motor electrophysiological mapping of the cerebellum in humans

Cerebellar damage during posterior fossa surgery in children can lead to ataxia and risk of cerebellar mutism syndrome. Compartmentalisation of sensorimotor and cognitive functions within the cerebellum have been demonstrated in animal electrophysiology and human imaging studies. Electrophysiological monitoring was carried out under general anaesthesia to assess the limb sensorimotor representation within the human cerebellum for assessment of neurophysiological integrity to reduce the incidence of surgical morbidities. Thirteen adult and paediatric patients undergoing posterior fossa surgery were recruited. Sensory evoked field potentials were recorded in response to mapping (n = 8) to electrical stimulation of limb nerves or muscles. For motor mapping (n = 5), electrical stimulation was applied to the surface of the cerebellum and evoked EMG responses were sought in facial and limb muscles. Sensory evoked potentials were found in two patients (25%). Responses were located on the surface of the right inferior posterior cerebellum to stimulation of the right leg in one patient, and on the left inferior posterior lobe in another patient to stimulation of left forearm. No evoked EMG responses were found for the motor mapping. The present study identifies challenges with using neurophysiological methods to map functional organization within the human cerebellum and considers ways to improve success.

The eagle jugular syndrome as the cause of delayed intracranial hemorrhage after microvascular decompression for hemifacial spasm: A case report

Background: Eagle syndrome is a rare disorder whereby an elongated styloid process (ESP) causes not only some otolaryngological symptoms, but also cerebrovascular events caused by compression of the carotid artery. In recent years a syndrome, denominated as Eagle jugular syndrome, involving internal jugular vein (IJV) compression caused by an ESP has been proposed as a variation of Eagle syndrome. Clinical impact of the Eagle jugular syndrome on neurosurgical procedures has not been reported yet. Case Description: We present a case of a 68-year-old woman who underwent microvascular decompression for hemifacial spasm of the left side and developed delayed intracranial hemorrhage on postoperative day 3. We also demonstrate that this patient developed ipsilateral IJV stenosis between an ESP and the muscle bundle of the rectus capitis lateralis with antero-flexion neck position, which would induce venous congestion in addition to surgical disruption of emissary vein. Conclusion: This case is the first report demonstrating the association of an ESP with postoperative delayed intracranial hemorrhage. Our report elucidates the importance of the awareness among neurosurgeons of considering the ESP as an important bony anomaly, especially when planning for posterior fossa surgery.

Neurosurgery

This chapter discusses the anaesthetic management of neurosurgery. It begins with general principles of neurosurgery, including management of intracranial pressure. Surgical procedures covered include craniotomy (including awake craniotomy); insertion of ventriculo-peritoneal (VP) shunt; evacuation of traumatic intracranial haematoma; pituitary surgery; posterior fossa surgery; and interventional radiology treatment of intracranial vascular lesions (with particular attention to subarachnoid haemorrhage (SAH)). The management of venous air embolism is described, along with a discussion of the particular circumstance of resuscitation during neurosurgery.

Dural Sinus Thrombosis after Resection of Vestibular Schwannoma using Suboccipital Retrosigmoid Approach - Thrombosis Classification and Management Proposal.

ObjectiveDural sinus thrombosis is one of the complications after posterior fossa surgery. However, that topic is not described well with regard to vestibular schwannoma surgery using the unique suboccipital retrosigmoid approach.MethodsWe analyzed retrospectively medical records and radiological investigations of 116 patients. The including criteria were: histopathologically confirmed vestibular schwannoma operated on using the retrosigmoid approach, preoperative and postoperative contrast enhanced MRI, at least 1-year follow-up. ResultsThe patient group included 36% males, 64% females. The average age was 47.3±13.9 years. 60% of tumors were classified as T4b according to the Hannover scale and their mean volume was 13.73±10.28 cm3. There were no signs of thrombosis preoperatively. In 26 (22%) cases, postoperative changes in the dural sinuses were found. In 7 (27%) cases there was an external compression by the hemostatic agent, in 19 (73%) cases a thrombus was visualized in the sinus lumen. The size of the sinus, age, tumor size were not risk factors for thrombosis, whereas an intraoperative sinus injury was a statistically significant risk factor (p=0.0012). All of the patients diagnosed with thrombosis were in good clinical condition in distant follow-up (mRankin=0). Complete recanalization was observed in 58% of cases after 1-year follow-up.ConclusionsPostoperative changes in the dural venous sinuses are a frequent finding after vestibular schwannoma surgery using the suboccipital retrosigmoid approach. Intraoperative dural injury is a risk factor for thrombosis. Thrombosis in that group of patients is usually asymptomatic and does not influence the prognosis.

The semisitting position in pediatric neurosurgery: pearls and pitfalls of a 10-year experience

OBJECTIVE The authors sought to investigate the pearls and pitfalls of using the semisitting position in pediatric neurosurgery, with special focus on related morbidity and surgical practicability. METHODS All pediatric cases at a single institution were evaluated retrospectively. Those patients who underwent procedures in the semisitting position between December 2010 and December 2020 were included in the final analysis. Results were compared with all children who underwent surgery in the prone position for posterior fossa lesions within the same time frame. RESULTS A total of 42 posterior fossa surgeries were performed in 38 children in the semisitting position between December 2010 and December 2020. The mean patient age at the time of surgery was 8.9 years (range 13 months–18 years). The data of 24 surgeries performed in the prone position in 22 children during the same time frame were analyzed in comparison. Three children (7.9%) were diagnosed with a persistent foramen ovale preoperatively. The surgery was completed in all cases. The incidence of venous air embolism (VAE) was 11.9%. There was no VAE-related hemodynamic instability, infarction, or death. Endoscopic techniques were applied safely in 14 cases (33.3%). Postoperative pneumocephalus occurred significantly more frequently in patients who had undergone procedures in the semisitting position (p < 0.05), but without the need for intervention. During 1 surgery (2.4%), the patient experienced a postoperative skull fracture and epidural bleeding due to the skull clamp application. Clinical status of the patients immediately after surgery was improved or stable in 33 of the 42 surgeries (78.6%) performed in the semisitting position. CONCLUSIONS With attentive performance and an experienced surgical team, the semisitting position is a safe option for posterior fossa surgery in the pediatric population. With a comparable complication profile, the semisitting position offers excellent anatomical exposure, which is ideal for the application of endoscopic visualization. Careful skull clamp application and appropriate monitoring are highly recommended.

Strategies for Persistent Intracranial Infection Associated With Subcutaneous Effusion in the Posterior Fossa

Objective: Due to the particularity of anatomy, there are many subcutaneous effusions after posterior fossa surgery. This paper discusses the characteristics and treatment strategies of persistent infection related to subcutaneous effusions in the posterior fossa. Methods: Seventeen patients with persistent intracranial infection after neurosurgical posterior fossa surgery from March 2015 to July 2020 were retrospectively analyzed. According to different stages of infection, the treatment process of intracranial infection was divided into the acute infection stage, clinical response stage and infection cure stage, and the measures taken in the different stages were summarized.Results: Compared with the acute infection stage, the indices of body temperature, blood and cerebrospinal fluid in the clinical response stage were improved, but there was no significant difference. There was a significant difference in each index between the acute infection stage and the infection cure stage. After the infection was cured, 17 patients were significantly relieved or cured of subcutaneous effusions by various methods.Conclusion: It is necessary to be alert to the existence of subcutaneous effusions in cases of poor effects or repeated infections after routine treatment. Multiple replacements and flushing of subcutaneous effusions are an important means of treating this kind of infection.