1. Trephine Syndrome and its Differential eEdE-104
Yueyang Guo, MD
Rajul Pandit, MD

2. Disclosures
Neither presenter has financial relationships or conflicts of interest in relation to the topic of this conference.

3. Learning Objectives
1. Understand the pathophysiology and clinical presentation of trephine syndrome and related syndromes.
2. Identify the key features of trephine syndrome by CT and MRI and be able to differentiate from related syndromes.
3. Understand the management and prognosis of trephine syndrome.

4. Definition
Trepanation/trephination is the creation of a burr hole upon the calvarium, usually to relieve pressure.

5. A Little History… Syndrome of the Trephined
Originally coined by Grant in 1939 and thought to be psychiatric in nature due to a “sense of vulnerability” from the lack of an intact cranial vault
In the 1970s, the term “syndrome of the sinking skin flap” was used by Yamaura in an attempt to describe more objective findings.

6. Pathophysiology
Exposure of intracranial contents to atmospheric pressure leads to altered CSF flow dynamics, brain deformation, and reduced cerebral perfusion.
Severe pressure differences (eg. CSF drainage causing intracranial hypotention) can cause to paradoxical brain herniation away from the craniectomy site.

7. Clinical Behavior Epidemiology:
13%-24% of patients after decompressive craniectomy
CSF shunt/drain/leak increases risk
Time Course:
onset of clinical symptoms in the intermediate to late postoperative periods ( days after craniectomy)
clinical improvement following treatment (cranioplasty)
Presenting Signs & Symptoms:
sunken calvarial skin flap
nonspecific and frequently vague symptoms
headache, seizure, dizziness, fatiguability, sensorimotor deficits, cognitive/behavioral changes
paradoxical brain herniation:
decreased consciousness, autonomic instability, brainstem release signs

8. CT & MR Features
Imaging features of trephine syndrome without clinical correlation is not trephine syndrome – ie. trephine syndrome must be diagnosed clinically.
Key Features:
concave deformity of the subgaleal-dural complex at the craniectomy site
MR or CT perfusion demonstrates decreased cerebral perfusion
Differentiating Features:
paradoxical brain herniation:
subfalcine or descending transtentorial herniation
external brain tamponade:
fluid collection overlies & exerts mass effect on subgaleal-dural complex
1. Sinclair AG, Scoffings DJ. Imaging of the post-operative cranium. Radiographics Mar; 30(2):

9. Case 1 A
A 33 year old female status post decompressive hemi-craniectomy after PCOM aneurysm rupture complicated by MCA infarction presents with new onset seizure 2 months after surgery. B

10. Case 1 Trephine Syndrome
A: Immediate postop scan: A large left MCA infarct is seen. A right frontal approach ventriculostomy is also partially visualized.
B: 2 months postop scan: There is a sunken appearance to the left galeal-dural complex. A right parietal ventriculo-peritoneal shunt is now seen.
The patient was treated with cranioplasty with resolution of symptoms and imaging features. B

11. Case 2 A
A 37 year old male status post hemicraniectomy for severe head trauma develops gradually- worsening somnolence during inpatient rehab 2 months after surgery. B

12. Case 2 Paradoxical Brain Herniation
A: Immediate postop scan: Post- traumatic changes in the left hemisphere. A ventriculostomy is partially seen.
B: 2 months postop scan: There is a sunken appearance to the left galeal-dural complex. There is marked midline shift away from the craniectomy site.
The patient was treated with cranioplasty with resolution of acute symptoms and imaging features. B

13. Case 3
A 22 year old male status post hemicraniectomy for severe head trauma develops severe headaches and left-sided head bulge 1 month after surgery.

14. Case 3 External Brain Tamponade
1 month postop scan: There is a subgaleal-subdural fluid collection displacing the skin flap outward while exerting mass effect on the brain.
The fluid collection was surgically evacuated and found to be a chronic hematoma. The patient’s symptoms improved after evacuation.

15. Differential Diagnosis
Clinical Entity
Signs & Symptoms
Imaging Findings
trephine syndrome /
motor trephine syndrome / sunken skin flap syndrome
concave skin flap +
clinical signs/symptoms
concave skin flap, decreased cerebral perfusion
paradoxical brain herniation
signs of brain herniation
+/-
midline shift (subfalcine herniation)
effacement of basal cisterns (descending transtentorial herniation)
external brain tamponade
convex, tense skin flap +
neurologic deterioration
convex skin flap
subgaleal collection
mass effect on underlying brain

16. Differential Diagnosis
Trephine Syndrome
Paradoxical Brain Herniation
External Brain Tamponade

17. Management & Prognosis
Paradoxical brain herniation is a neurosurgical emergency.
Treatment:
Trendelenburg positioning and clamping the ventricular drain/shunt, if present, can be performed rapidly.
Cranioplasty is definitive treatment.
Standard treatment for herniation aimed at lowering intracranial pressure will exacerbate paradoxical brain herniation.
Post-cranioplasty recovery is usually complete and rapid (24 hours to 2 weeks).

18. Summary
1. Trephine syndrome is a post-craniectomy complication caused by exposure of the brain to atmospheric pressure.
2. Paradoxical brain herniation is a severe form and a neurosurgical emergency, usually in the setting of intracranial hypotension from CSF drainage.
3. Trephine syndrome must be diagnosed clinically. Imaging findings include concave subgaleal-dural complex at the craniectomy site and decreased cerebral perfusion. Midline shift and basal cistern effacement suggest paradoxical herniation.
4. The differential diagnosis of trephine syndrome and paradoxical herniation includes external brain tamponade.
5. Definitive treatment for trephine syndrome and paradoxical herniation is cranioplasty.

19. References
Sedney CL, Dillen W, Julien T. Clinical spectrum and radiographic features of the syndrome of the trephine. J Neurosci Rural Pract Jul-Sep; 6(3):
Jeyaraj P. Importance of early cranioplasty in reversing the “syndrome of the trephine/motor trephine syndrome/sinking skin flap syndrome.” J Maxillofac Oral Surg Jul-Sep; 14(3):
Annan M, et al. Sinking skin flap syndrome (or syndrome of the trephine): a review. British Journal of Neurosurgery. 2015; 29(3):
Gadde J, Dross P, Spina M. Syndrome of the trephined (sinking skin flap syndrome) with and without paradoxical herniation: a series of case reports and review. Del Med J Jul; 84(7): 213-8
Sinclair AG, Scoffings DJ. Imaging of the post-operative cranium. Radiographics Mar; 30(2):
Akins PT, Guppy KH. Sinking skin flaps, paradoxical herniation, and external brain tamponade: a review of decompressive craniectomy management. Neurocrit Care ; 9(2):