Question 25

a) Describe the various types of brain herniation with clinical features and radiological features.
(70% marks)

b) Describe the role of decompressive craniotomy in Traumatic Brain Injury. (30% marks)

College answer

Not available.

Herniation	Radiological features	Clinical features
Falcine	Displacement of the cingulate gyrus under the falx cerebri	Leg weakness
Midline shift	Midline shift of the septum pellucidum	A decreased level of consciousness, proportional to the degree of shift.
Uncal	Uncus and medial temporal lobe displaced medially Effacement of the suprasellar cistern The hippocampus obliterates the quadrigeminal cistern midbrain effaced and displaced laterally	Ipsilateral fixed dilated pupil (3rd nerve palsy) Decreased level of consciousness Hemiparesis Cortical blindness
Central tentorial	Obliteration of basal subarachnoid cisterns Increased brainstem sagittal diameter Inferior displacement of the basilar artery	Coma Parinaud's syndrome: Diabetes insipidus
Tonsillar	Cerebellar tonsil below the foramen magnum	Coma Apnea Hypertension
Upward	Flattened quadrigeminal cistern "Spinning top" midbrain Hydrocephalus	Coma Miosis (reactive) Absent or assymmetric doll's eye Decerebrate posuring
Transcalvarial	Depends where the defect is	Depends where the defect is

b) Note that the college asked to "discuss" the practice of decompressive craniectomy in TBI, not "critically evaluate" it. Still:

Rationale for decompressive craniectomy:

Raised intracranial pressure contributes to secondary brain injury and morbidity/mortality from TBI
Intracranial pressure is governed by the Monro-Kellie Doctrine, where intracranial content is confined within a finite space and any expansion of one component produces increased pressure on other components
Decompressive craniectomy increases the volume available to the intracranial contents
The consequence should be decreased ICP and decreased secondary brain injury.

Advantages:

Maybe some sort of mortality benefit (cohort studies such as Sonuca et al, 2010; as well as RESCUIicp)
Shorter ICU stay
Less ICP-targeting interventions
Lower ICP

Complications of decompressive craniectomy:

Evidence for decompressive craniectomy in TBI:

Hahn, F. J., and J. Gurney. "CT signs of central descending transtentorial herniation." American Journal of Neuroradiology 6.5 (1985): 844-845.

Brazis, P., J. Masdeu, and Jose Biller. "Localization in Clinical Neurology." 2007 Lippincott Williams & Wilkins

Cuneo, Richard A., et al. "Upward transtentorial herniation: seven cases and a literature review." Archives of neurology 36.10 (1979): 618-623.

Cooper, D. James, et al. "Decompressive craniectomy in diffuse traumatic brain injury." New England Journal of Medicine 364.16 (2011): 1493-1502.

Hutchinson, Peter J., et al. "Trial of decompressive craniectomy for traumatic intracranial hypertension." New England Journal of Medicine 375.12 (2016): 1119-1130.

Torres, Roland. "DECRA… Where do we go from here?." Surgical neurology international 3 (2012).