Sinking skin flap syndrome and trapped 4th ventricle

Case contributed by Dr Andrei Tsoriev


One year after the severe traumatic brain injury in the road traffic accident. Bilateral skull trepanation was performed for subdural hematomas evacuation, with subsequent cranioplasty. Bilateral ventricular shunts were inserted to treat late-onset non-resorptive hydrocephalus - a left shunt is inserted in the anterior horn and a right shunt in the posterior horn of the lateral ventricle.

Patient Data

Age: 30
Gender: Male

There is severe dilatation of the left and the same severity collapse of the right lateral ventricles. Midline shift is 10 mm. Left frontal bone is grafted with Methyl Methacrylate, small metal particles from the saw, used to cut the bone, cause magnetic susceptibility artifacts on both sides. Artifacts are more pronounced on the left side. There is an invagination of skin flap inside the skull, caused by the pressure difference between left, right lateral ventricles and the atmosphere. 

There is an isolation of the fourth ventricle due to adhesions in both distal part of cerebral aqueduct and foramen of Magendi, so-called "isolated 4th ventricle". 

Case Discussion

Sinking skin flap syndrome or “syndrome of the trephined” is an infrequent complication after a massive skull bone removal, with an invagination of the cutaneous flap, covering the bone defect, with neurological symptoms like mental status change, intense headache, focal neurological deficit or epilepsy.

This condition can appear due to the existence of an atmospheric pressure gradient, especially after CSF diversion procedures such as shunting, dehydration, general CSF hypovolemia, and change of head position.

This case is somewhat unique since the condition appeared after the onset of the right shunt malfunction in the form of hyperdrainage. 

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Case information

rID: 48129
Published: 20th Sep 2016
Last edited: 14th Aug 2019
Inclusion in quiz mode: Included

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