Lateral-type posterior fossa ependymomas in pediatric patients: a national collaborative study.

Purpose: To review a multicentric series of lateral-type posterior fossa ependymomas operated in the last ten years and to analyze the factors related to clinical evolution and tumor survival.

Methods: Descriptive, retrospective study. Active members of the Spanish Society of Pediatric Neurosurgery were invited to participate in this multicentric study.

Direct cortical stimulation with cylindrical depth electrodes in the interhemispheric fissure for leg motor evoked potential monitoring.

Objective: To evaluate cylindrical depth electrodes in the interhemispheric fissure as an alternative to subdural strip electrodes for direct cortical stimulation (DCS) leg motor evoked potential (MEP) monitoring.

Methods: A cylindrical depth electrode was positioned in the interhemispheric fissure of 37 patients who underwent supratentorial brain surgery. Leg sensory and motor cortices were localized by highest tibial nerve somatosensory evoked potential amplitude and lowest DCS leg MEP threshold; the lowest-threshold electrode was then used for DCS leg MEP monitoring.

Electrical stimulation threshold in chronically compressed lumbar nerve roots: Observational study.

Objectives: Intraoperative neuromonitoring (IONM) is a common practice in spinal surgery, mostly during pedicle screw placement. However, there is not enough information about the factors that can interfere with IONM data. One of these factors may be existing damage of the nerve root whose function must be preserved.

[Arachnoid cysts: Embriology and pathology].

There is still great controversy surrounding the origin of the arachnoid cyst. The most accepted theory in the case of congenital cysts explains how they are formed from an anomalous development of the arachnoid membrane, which is unfolded allowing the accumulation of cerebrospinal fluid inside and creating a cyst. This theory seems to explain the origin of convexity and sylvian cistern arachnoid cysts, whereas those in other locations might be due to other mechanisms.

Acute hemicerebellitis with obstructive hydrocephalus in a young adult.

Background: Acute cerebellitis is a rare entity, described in the pediatric population, usually of viral or autoimmune origin, bilateral and symmetric, and with good prognosis. Only 13 cases of unilateral cerebellitis have been reported thus far. To the best of our knowledge, this is the first case of hemicerebellitis in the literature reported in a young adult that caused acute hydrocephalus requiring surgical treatment.