Postoperative posterior fossa pseudomeningocele: risk factors and management strategies

Background: Pseudomeningocele is a considerable morbidity after posterior fossa surgery. Its incidence and optimal management strategies are quite unclear. Hence the objective of this study is to define the risk factors and evaluate the management strategies and to study the incidence and morbidity of postoperative posterior fossa pseudomeningocele.Methods: A retrospective study of 33 patients undergone posterior fossa surgery for variety of diseases in the department of neurosurgery, Saveetha Medical College and Hospital from January 2015 to December 2018 with emphasis on incidence of pseudomeningocele,its morbidity and treatment strategies.Results: Out of 33 posterior fossa surgeries performed, 9 developed pseudomeningocele. Hence the incidence of pseudomeningocele in hospital is 27.27%. Out of 9 patients who developed pseudomeningocele, 6 patients were symptomatic, and aspiration was done to 5 patients and one patient underwent resurgery. That one patient underwent subgaleal-peritoneal shunt, excision of recurrent tumor was performed after which the symptoms subsided.Conclusions: Psudomeningocele is a well-known complication of posterior fossa surgery. The risk factors for pseudomeningocele formation after posterior fossa surgery has been evaluated. Age, sex and type of surgery are found to be a risk factors in our study. Conservative management is effective in most cases to reduce the symptoms. Surgical intervention is advocated, only when conservative treatment fails. Preventive measures like careful perioperative planning, strict adherence to aseptic techniques, usage of autologous pericranium with dural sealant augmentation, polyethylene glycol hydrogel dural sealant can be adopted.

Resección microquirúrgica de schwannoma vestibular grado IVa con preservación de la función facial / Microsurgical resection of vestibular schwannoma grade IVa with preservation of facial function

Introducción: La cirugía de los schwannoma vestibulares constituye un desafío para los neurocirujanos. Debido a que se trata de un tumor benigno la resección completa de la lesión implica la curación del paciente. Sin embargo, este objetivo no siempre es fácil de lograr preservando la función de los nervios facial y acústico, especialmente en tumores de gran tamaño. Objetivos: Presentar detalles técnicos de la cirugía de resección de un schwannoma vestibular de gran tamaño (IVa) en el que se pudo preservar la función facial. Materiales y métodos: Se presenta el caso de una paciente femenina de 36 años que consultó por hipoacusia izquierda. En la RM preoperatoria se evidenciaba una lesión ocupante de espacio del ángulo pontocerebeloso izquierdo compatible con schwannoma vestibular con compresión del tronco encefálico y sin efecto de masa sobre el IV ventrículo (grado IVa). Mediante un abordaje suboccipital retromastoideo en posición de decúbito lateral se realizó la resección de la lesión en forma completa asistida por monitoreo del nervio facial. En todo momento se pudo preservar el plano aracnoideo que separaba el tumor de los nervios adyacentes. Resultados: Se logró una resección macroscópicamente completa con preservación de la función del nervio facial. La paciente permaneció internada por 96 hs en el postoperatorio sin complicaciones derivadas del procedimiento. Conclusión: La preservación del plano aracnoideo es un detalle técnico de mucha importancia para disminuir las posibilidades de lesión de los nervios facial y auditivo en la cirugía de resección de los schwannoma vestibulares.

Introduction: The surgery of vestibular schwannomas is a challenge for neurosurgeons.Because it is a benign tumor, complete resection of the lesion involves healing the patient. However, this objective is not always easy to achieve, preserving the function of both the facial and acoustic nerves, especially when dealing with large tumors. Objective: The objective of the video is to present some technical details of a large vestibular schwannoma (IVa) surgery in which the facial function could be preserved. Materials and methods: We present the case of a 36-year-old female patient who consulted for left hearing loss. The preoperative MRI showed a space- occupying lesion of the left pontocerebellar angle, which was compatible with vestibular schwannoma, with compression of the brainstem but with no mass effect on the IV ventricle (grade IVa). By means of a retromastoid suboccipital approach in the lateral prone position, the lesion was completely resected assisted by neurophysiological monitoring of the facial nerve. At all times, the arachnoid plane separating the tumor from the adjacent nerves was preserved. Results: A macroscopically complete resection was achieved preserving the facial nerve function. The patient stayed hospitalized for 96 hours during the postoperative period without any complication from the procedure. Conclusion: Preserving the arachnoid plane is a very important technical detail to reduce the possibilities of injury of the facial and auditory nerves in the vestibular schwannoma resection surgery.

Delayed Progressive Extradural Pneumatocele due to Incomplete Sealing of Opened Mastoid Air Cell after Micro-Vascular Decompression

A case of delayed progressive extradural pneumatocele after microvascular decompression (MVD) is presented. A 60-year-old male underwent MVD for hemifacial spasm; the mastoid air cell was opened and sealed with bone wax during surgery. One month after surgery, the patient complained of tinnitus, and progressive extradural pneumatoceles without cerebrospinal fluid (CSF) leakage was observed. Revision surgery was performed and the opened mastoid air cell was completely sealed with muscle patch and glue. The patient's symptoms were resolved, with no recurrence of pneumatoceles at 6 month follow up. Progressive extradural pneumatocele without CSF leakage after posterior fossa surgery is a very rare complication. Previous reports and surgical management of this rare complication are discussed.

Transient Cerebellar Mutism after Total Removal of Medulloblastoma in a Child: Case Report

Transient mutism resolving to cerebellar speech after posterior fossa surgery is a well recognized phenomenon, particularly in pediatric patients. The anatomic basis for this postoperative functional change is unclear, but may reside in the dominant superior cerebellar hemisphere or the medial deep cerebellar nuclei. We report a case of a 9-year-old boy who presented for surgical resection of a medulloblastoma. Preoperatively, his complaint consisted of headache, nausea, vomiting and cerebellar ataxia. He had normal speech. At one day after operation, suddenly he was unable to speech, however, communication through a variety of verbal cues, including sign language was possible. His mutism lasted 12 days and cerebellar dysarthria was slowly resolved.

Sudden Respiratory Arrest after Surgery for Cerebellar Cystic Astrocytoma

The authors experienced a case of cystic cerebellar astrocytoma which showed sudden respiratory arrest after an uneventful operation. Preoperative cerebrospinal fluid diversion was not performed despite moderate hydrocephalus because we thought that complete removal of tumor enables the cerebrospinal fluid pathway to be reconstitute. After full awakening from anesthesia postoperatively, the patient's mentality deteriorated again rapidly with sudden respiratory arrest. Brain CT scan taken immediately after revealed no specific finding except moderate hydrocephalus which was the same degree as the preoperative one. This hydrocephalus was alleviated and the patient recovered slowly. We postulate several pathogenic mechanisms for this unusual event. First, chronic compression of fourth ventricle resulted in marked subependymal gliosis and obliteration of outlets of fourth ventricle. Therefore, postoperative reaccumlation of cerebrospinal fluid in ventricles caused serious pressure effect on the lower brain stem with resultant sudden respiratory arrest. Second, sudden decompression of brain stem might induce marked hemodynamic change in the brain stem. Third, there was some traction injury to brain stem by gravity in the sitting position. We suggest that preoperative cerebrospinal fluid diversion and its adeqaute postoperative maintenance is important in posterior fossa tumor surgery in cases with obliteration of perimesencephalic cistern and fourth ventricle, and with brain stem compression or angulation in preoperative magnetic resonance images.

Subdural Tension Pneumocephalus Follwing Surgery

Two cases of tension pneumocephalus follwing surgery are reported. Tension pneumocephalus appears to be another potential complication of the operation and should be considered whenever a patient fail to recover as expected following surgery. Peaking of frontal lobe, mountain appearance of frontal lobe, and air densities at the cisterns are characteristic findings of tension pneumocephalus. Its diagnosis and treatment are easy and simple.

Three Cases of Subdural Tension Pneumocephalus

Three patients development subdural pneumocephalus after undergoing posterior fossa surgery performed in sitting position. The mechanism for entry of air into the intracranial compartment is analogous to the entry of air into an inverted bottle. As the fluid pours out, air bubbles to the top of the container. A brow-up lateral skull radiograph with a horizontal beam provided prompt diagnosis and confirmed brain displacement as well as computerized tomography did. Tension pneumocephalus appears to be another potential complication of posterior fossa surgery in sitting position. This condition is easily diagnosed and treated, and should be considered whenever a patient fails to recover as expected following posterior fossa surgery.