Cerebellar Angle Research Articles

Interindividual differences in posterior fossa morphometry affect cerebellar tDCS-induced electric field strength

ObjectiveClinical, behavioural, and neurophysiological effects of cerebellar transcranial direct current stimulation (tDCS) are highly variable and difficult to predict. We aimed to examine associations between cerebellar tDCS-induced electric field strength, morphometric posterior fossa parameters, and skin-cerebellum distance. As a secondary objective, field characteristics were compared between cephalic and extracephalic electrode configurations. MethodsElectric field simulations of midline cerebellar tDCS (7 × 5 cm electrodes, current intensities of 2 mA) were performed on MRI-based head models from 37 healthy adults using buccinator, frontopolar, and lower neck reference electrodes. Average field strengths were determined in eight regions of interest (ROIs) covering the anterior and posterior vermis and cerebellar hemispheres. Besides skin-cerebellum distance, various angles were measured between posterior fossa structures. Multivariable linear regression models were used to identify predictors of field strength in different ROIs. ResultsSkin-cerebellum distance and “pons angle” were independently associated with field strength in the anterior and posterior vermis. “Cerebellar angle” and skin-cerebellum distance affected field strength in anterior and posterior regions of the right cerebellar hemisphere. Field strengths in all examined cerebellar areas were highest in the frontopolar and lowest in the lower neck montage, while the opposite was found for field focality. The lower neck montage induced considerably less spreading toward anterior cerebellar regions compared with the buccinator and frontopolar montages, which resulted in a more evenly distributed field within the cerebellum. ConclusionIn addition to skin-cerebellum distance, interindividual differences in posterior fossa morphometry, specifically pons and cerebellar angle, explain part of the variability in cerebellar tDCS-induced electric field strength. Furthermore, when targeting the midline cerebellum with tDCS, an extracephalic reference electrode is associated with lower field strengths and higher field focality than cephalic montages. SignificanceThis study identifies two novel subject-specific anatomical factors that partly determine cerebellar tDCS-induced electric field strength and reveals differences in field characteristics between electrode montages.

ACOUSTIC SCHWANNOMA WITH INTRATUMORAL HEMORRHAGE –REPORT OF AN UNUSUAL COMPLICATION

Acoustic Schwannoma is a benign neoplasm of the 8th cranial nerve pair, and accounts for 8-10% of all intracranialtumors. Intratumoral haemorrhage is unusual in these tumors and can lead to hydrocephalus or aggravate a preexisting condition. This paper reports a case of acoustic Schwannoma in a child with complication with intratumoral hemorrhage that lead patient to death. Female patient, 9 years old, presented anacusis on the right, sudden, progressing with vomiting, intense headache and vertigo. Magnetic resonance imaging of the skull showed expansive lesion in the cistern of the right cerebellar angle, with content inside the internalauditory canal, with compression of the adjacent brain stem. The diagnostic hypothesis was acoustic Schwannoma. It progressed with worsening of headache, initially controlled with medication and later loss of consciousness. Computed tomography of the skull revealed an expansive lesion in the cistern of the right cerebellar angle with signs of bleeding with extension to the ventricular system. External ventricular shunt was performed, but the patient evolved with several complications, septic shock and death. Intratumoral hemorrhage in the acoustic Schwannoma is a rare event, but its occurrence worsens the clinical picture and may lead to death of the patients due to intracranial hypertension.

Glioblastoma Multiforme Localizado no Ângulo Pontocerebelar. Relato de caso

Introdução: O glioblastoma multiforme é o tumor primário mais comum do sistema nervoso central. A localização preferencial é supratentorial, sendo considerado rara sua localização na fossa posterior. O exame de ressonância magnética (RM) é fundamental para o diagnóstico diferencial com outras lesões localizadas no ângulo pontocerebelar. O tratamento é cirúrgico associado a radioterapia e quimioterapia. Relato do caso: Paciente de 60 anos de idade com história de cefaleia, diminuição da acuidade auditiva à direita e paralisia facial periférica à direita. Resultado: Ressonância magnética do crânio demonstrou lesão expansiva no ângulo pontocerebelar direito, foi submetido a craniectomia suboccipital direita e exérese total da lesão. Anátomo-patológico resultou em glioblastoma multiforme. Conclusão: O glioblastoma multiforme localizado na fossa posterior apresenta manifestação clínica similar a outras lesões nesta região. O diagnóstico correto é importante para o planejamento terapêutico.

Hemifacial Spasms and Cerebellar Angle Tumors

Two children, aged 3 years, with hemisomatic spasms caused by tumors in the ipsilateral cerebellopontine angle are reported from the Division of Pediatric Neurology and Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX.