Objective: To describe a rare case of reversible ventral brainstem syndrome secondary to alternating

overdrainage and underdrainage of a ventriculoperitoneal shunt.

Background: Brainstem dysfunction secondary to cerebrospinal fluid (CSF) shunting is a rare but potentially

reversible complication. Alternating episodes of overdrainage and underdrainage can produce

mechanical traction and compression of ventral brainstem structures, resulting in impaired

consciousness, cranial nerve palsies, and extrapyramidal symptoms.

Method: We describe the clinical evolution, neuroimaging features, and therapeutic response of a 21-

year-old man with congenital hydrocephalus who developed a ventral brainstem syndrome

following valve replacement of a ventriculoperitoneal (VP) shunt.

Results: A 21-year-old male with a history of congenital hydrocephalus underwent VP shunt valve

replacement due to suspected malfunction. Fifteen days later, he developed psychomotor

slowing, hypomimia, somnolence, and marked rigidity with severe bilateral upper limb tremor. A

left abducens palsy (VI) and a right oculomotor palsy (III) were found during examination,

indicating pontine and ventral midbrain involvement.

Neuroimaging revealed alternating ventricular dilatation and collapse, with initial overdrainage

and subsequent underdrainage, which is consistent with dynamic brainstem distortion. The

patient underwent endoscopic third ventriculostomy and valve adjustment. Subsequently,

levodopa was initiated, producing a clear improvement in rigidity and tremor, while modafinil was

added for persistent hypersomnolence. Over the following weeks, his level of alertness and

motor function progressively improved, with full resolution of cranial nerve deficits.

The patient achieved functional independence and continued to recover during rehabilitation.

Conclusion: This case highlights a rare and reversible ventral brainstem syndrome secondary to alternating

CSF overdrainage and underdrainage after VP shunt manipulation. Early recognition and timely

management—including ventriculostomy, valve readjustment, and symptomatic therapy with

levodopa and modafinil—can lead to complete neurological and functional recovery.

References: 1. Jöhr J, Alioth A, Catalano Chiuvé S, Nazeeruddin S, Belouaer A, Daniel RT, et al. Avoiding misdiagnosis in global rostral midbrain syndrome (GRMS): Clinical insights and neurorehabilitation approaches. Journal of Clinical Medicine. 2024;13:5752. doi:10.3390/jcm13195752.
2. Villamil F, Varela F, Caffaratti G, Ricciardi M, Cammarota A, Cervio A. Global rostral midbrain syndrome (GRMS) and corpus callosum infarction in the context of shunt overdrainage. Clinical Neurology and Neurosurgery. 2022;213:107098. doi:10.1016/j.clineuro.2021.107098.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/ventral-brainstem-syndrome-following-shunt-overdrainage-and-underdrainage-a-rare-and-reversible-complication-of-ventriculoperitoneal-shunting/