Midline Brain Shift After Hemispheric Surgery: Natural History, Clinical Significance, and Association With Cerebrospinal Fluid Diversion

Abstract

BACKGROUND: Hemispherectomy and its modern variants are effective surgical treatments for medically intractable unihemispheric epilepsy. Although some complications such as posthemispherectomy hydrocephalus are well documented, midline brain shift (MLBS) after hemispheric surgery has only been described anecdotally and never formally studied. OBJECTIVE: To assess the natural history and clinical relevance of MLBS and determine whether cerebrospinal fluid (CSF) shunting of the ipsilateral surgical cavity exacerbates MLBS posthemispheric surgery. METHODS: A retrospective review of consecutive pediatric patients who underwent hemispheric surgery for intractable epilepsy and at least 6 months of follow-up at UCLA between 1994 and 2018 was performed. Patients were grouped by MLBS severity, shunt placement, valve type, and valve opening pressure (VOP). MLBS was evaluated using the paired samples t-test and analysis of covariance adjusting for follow-up time and baseline postoperative MLBS. RESULTS: Seventy patients were analyzed, of which 23 (33%) required CSF shunt placement in the ipsilateral surgical cavity for posthemispherectomy hydrocephalus. MLBS increased between first and last follow-up for nonshunted (5.3 ± 4.9-9.7 ± 6.6 mm, P < .001) and shunted (6.6 ± 3.5-16.3 ± 9.4 mm, P < .001) patients. MLBS progression was greater in shunted patients (P = .001). Shunts with higher VOPs did not increase MLBS relative to nonshunted patients (P = .834), whereas MLBS increased with lower VOPs (P = .001). Severe MLBS was associated with debilitating headaches (P = .048). CONCLUSION: Patients undergoing hemispheric surgery often develop postoperative MLBS, ie, exacerbated by CSF shunting of the ipsilateral surgical cavity, specifically when using lower VOP settings. MLBS exacerbation may be related to overshunting. Severe MLBS is associated with debilitating headaches.

A predictive model for awakening in patients with prolonged disorders of consciousness after craniocerebral injury

“…The midline brain structures include both neuronal efferent and afferent channels and the hypothalamic-pituitary axis and regulate heartbeat and respiration. [ 17 , 18 ] Therefore, minor damage to the midline brain structures can cause cardiac and respiratory abnormalities, and in severe cases, even arrest, and abnormalities in endocrine function. Compression damage to the brain tissue by intracranial hematoma can affect patients’ prognosis; thus, patients with shifted midbrain have more complications, severe conditions, difficult clinical recovery, and poorer prognosis.…”

Hemispheric epilepsy surgery for hemimegalencephaly: The UCLA experience

“…However, there is preliminary evidence that the addition of choroid plexus cauterization to hemispheric surgery may reduce PHH 15 . Although almost all patients had some degree of postoperative midline brain shift on MRI, patients requiring a CSF shunt had a significantly greater ipsilateral midline shift, which has been associated with severe headaches, especially in patients with low valve‐opening pressures due to over‐shunting, in a retrospective review of 70 post‐hemispherectomy patients 45 . Thus the sequelae of PHH and CSF over‐shunting should be considered carefully and monitored post‐operatively.…”

Advances in the intraoperative delineation of malignant glioma margin

“…Various techniques in detecting tumor molecular or metabolic markers by physical or chemical methods allow for depicting millimeter-level resolution boundaries (6,7). Moreover, due to the impact of brain shifting, it is necessary for various techniques to be performed and to amend intraoperative detection (8)(9)(10).…”