Sinken skin flap syndrome

Syn : Sunken skin flap syndrome, Trephine Syndrome , Syndrome of Trephined skull,Post hemicraniectomy Paradoxical Herniation, 

Sinken skin flap syndrome 

Sinken skin flap syndrome   

An uncommon late post operative complication usually occurs after a month of surgery.

Patient who undergo hemi craniectomy for reasons like malignant MCA Infarction, hemispheric contusion or sub dural hematoma present with new onset of complaints like headaches, seizures, dizziness,easy fatiguability and mood changes. 

On examination often a depressed skin flap that is sunken appearance of the skin flap noted.

On CT / MR imaging a depressed galeal dural complex at the craniectomy site and concave deformity of the underlying brain parenchyma.

Incidence: 
In a study of 108 patients who underwent decompressive craniectomy, trephine syndrome was reported in 13% and occurred between 28 and 188 days after surgery (reference : Yang XF, Wen L, Shen F, et al. Surgical complications secondary to decompressive craniectomy in patients with a head injury: a series of 108 consecutive cases. Acta Neurochir Wien) 2008;150(12): 1241–1247;discussion 1248)

Patholophysiology: Exposure of the intracranial contents to atmospheric pressure, which alters CSF hydrodynamics, deforms the brain, and reduces cerebral perfusion. (Reference: Akins PT, Guppy KH  Sinking skin flaps, paradoxical herniation, and external brain tamponade: a review of decompressive craniectomy management.Neurocrit Care 2008;9(2):269–276) 

Management : Some patients may show clinical improvement after the cranial defect repaired with cranioplasty the reason may be improved cerebral blood flow after cranioplasty. 

Paradoxical Herniation

Hemicraniectomy with Paradoxical herniation.
Note the VP shunt tube in situ. 

A very uncommon and further advanced complication of decompressive craniectomy and that is paradoxical internal herniations. Seen in patients with a large craniectomy defect who then undergo CSF drainage by either lumbar puncture or ventriculoperitoneal shunt result in marked decrease in Csf pressure, which leads to reduction in intracranial pressure making intra cranial content vulnerable to atmospheric pressure. This pressure imbalance particularly the negative intara cranial pressure deforms brain and mid line. 

On CT / MR Imaging a significant mid line shift away from the craniectomy side with subfalcine and or transtentorial herniations. Uncal herniation if severe may results in mid brain compression.

Clinically patient present with depressed level of consciousness, autonomic instability, signs of brainstem release, and focal neurologic deficits.

Management: Paradoxical herniation is a neurosurgical emergency and urgent treatment is necessary in order to increase intracranial pressure, to stop any CSF leakage, and restore the continuity of the calvaria.

Options include urgent placing the patient in Trendelenburg position and head inclined towards to craniectomy side, clamping ventricular shunts or drains, administering intravenous fluid. Cranioplasty as soon as possible. Paradoxical herniation also has been reported to be effectively and quickly reversed with a lumbar epidural blood patch or clamping ventricular shunt tube.