A 52-yr-old African American woman experienced a spontaneous right middle cerebral artery (MCA) aneurysm rupture treated with emergent right craniectomy and MCA artery clipping. Her acute hospitalization was complicated by cerebral vasospasm, respiratory failure requiring tracheostomy, pneumonia, and dysphagia requiring percutaneous gastrostomy tube placement. She was admitted to inpatient rehabilitation (IPR) 6 wks after her initial injury, requiring maximum to total assistance for functional tasks. She was making significant functional gains for approximately 2.5 wks. However, for a period of 4 days, she began to develop cognitive deficits, headache, and functional decline (new difficulty standing, eating, and with cognitive tasks) that worsened at the end of the day. Her vital signs were unremarkable. Physical examination was unchanged when lying in bed (left-sided weakness was stable when giving maximum effort), except for sunken craniectomy flap (Fig. 1).
The differential included urinary tract infection, pneumonia, aspiration events, electrolyte derangement, acute kidney injury, hepatic failure, seizure, and new intracranial pathology including new ischemic stroke, hemorrhagic stroke, and syndrome of the trephined (SoT). Complete blood count, complete metabolic panel, urinalysis, chest x-ray, electroencephalogram were unremarkable. Noncontrast computed tomography scan of the head revealed interval medialization of the craniectomy flap with local mass effect causing a 4-mm leftward shift with interval decrease in bilateral lateral and third ventricular size consistent with SoT (Fig. 2).
She was diagnosed with SoT and was placed in the Trendelenburg position between therapy sessions and overnight, which temporarily stalled her decline, returned her to baseline cognition, and allowed for participation in modified therapy sessions. After discussion with neurosurgery, she was discharged from IPR for definitive treatment of SoT with cranioplasty 5 days after diagnosis. She was readmitted to IPR 2 days after cranioplasty and completed an additional 3.5 wks in IPR before discharge to home, resulting in a total FIM gain of 65 points since her initial admission. She was evaluated in clinic 6 wks later and was functioning at a modified independent level.
- Syndrome of the trephined, also known as Sunken Flap Syndrome, is a rare but important cause of functional decline after craniectomy.1 Syndrome of the trephined occurs most commonly in the second month after craniectomy.2,3 Craniectomy is defined as removal of part of the skull and is usually performed to treat large elevation in intracranial pressure due to cerebral edema. This is in contrast to craniotomy, which involves evacuation of blood products through a drilled hole.
- The symptoms of SoT result from elevated intracranial pressure, cerebral edema, mass effect, and possibly herniation. The presentation is variable based on what part of the brain is affected. From most to least commonly expected: motor weakness cognitive deficits including impaired attention, memory, and/or executive function, language deficits, altered level of consciousness, headache, psychosomatic disturbances, seizures or electroencephalogram changes, and cranial nerve deficits.1 Often these symptoms do not follow the anticipated pattern of the patient's underlying pathology (the reason they were admitted to IPR) and present as an interruption in progress of the patient's anticipated course.1 Smaller CSF volume and lower CSF pressure are risk factors for development of SoT; age, size of effected brain tissue, presence of hygroma, or ex vacuo ventricular dilation have not been found to be associated with SoT.2
- Imaging findings correlate with those who clinically present with symptoms consistent with SoT.4 Radiographic features of SoT consist of mass effect with ventricular effacement, decrease in ventricular volume (especially the third ventricle), midline shift and possible herniation, and sunken flap.2,4 Sunken skin flap contour is the most sensitive finding (86% sensitive) and ventricular effacement is the most specific finding (95% specific).4
- Symptoms of patients with SoT will temporarily improve or remit when the patient is in the Trendelenburg position, but definitive treatment is with cranioplasty.1 Neurosurgical consultation should be sought immediately, because cranioplasty is indicated any time sunken flap syndrome is suspected.3 Urgency of cranioplasty is patient specific, but functional decline will only be temporized and will not improve without cranioplasty in patients with SoT.3
1. Ashayeri K, Jackson EM, Huang J, et al: Syndrome of the Trephined: a systematic review. Neurosurgery
2. Vasung L, Hamard M, Soto MCA, et al: Radiological signs of the syndrome of the trephined. Neuroradiology
3. Schorl M: Sinking skin flap syndrome (SSFS) - clinical spectrum and impact on rehabilitation. Cen Eur Neurosurg
4. Sedney CL, Dillen W, Julien T: Clinical spectrum and radiographic features of the syndrome of the trephined. J Neurosci Rural Pract