PMC2841607_01
Computed tomography of subdural hematoma and cerebral magnetic resonance imaging depicting early uncal herniation and mesiotemporal ischemic brain injury. (A) Preoperative cranial computed tomography scan reveals space-occupying subdural hematoma covering the left convexity. The hematoma causes a considerable midline shift at the level of the lateral ventricles. (B) Early diffusion- weighted magnetic resonance imaging (diffusion-weighted imaging) depicts a slight uncal herniation and a midline deviation at the level of the chiasmatic basal cistern. (C) Diffusion-weighted imaging sequences four days after surgery show circumscribed signal hyperintensity in the left uncal region indicative of local ischemic injury. Note the close anatomic proximity to the distal prechiasmatic course of the left optic nerve. (D) Corresponding hyperintensity in T2-weighted images indicates edema of the left temporomesial lobe that is consecutive to hypoperfusion and residual to preceding uncal herniation.
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Cerebral computed tomography (CT) revealed a subdural hematoma measuring 16 mm at its maximum thickness and covering almost the entire left convexity which caused a massive midline shift (Figure 1A). Rapid cerebral MRI of the same day depicted a beginning ipsilateral uncal herniation towards the chiasmatic cistern (Figure 1B). DWI of the cerebral MRI (Figure 1C) showed a signal hyperintense lesion within the left lateral, mesiobasal temporal lobe that was immediately adjacent to the distal prechiasmatic course of the affected optic nerve. Dull signal attenuation in corresponding apparent diffusion coefficient (ADC) maps, and gadolinium enhancement in T1 (not shown) led to the diagnosis of a subacute cerebral ischemic event. T2-weighted images indicated focal brain edema in line with regional hypoperfusion and the preceding uncal shift (Figure 1D). Thus, pathomorphologic and sequence-specific MRI criteria suggest a primary mechanic compression followed by secondary microcirculatory impairment of the afflicted brain area.