Multiple bilateral infarcts secondary to IV drug abuse-related cerebral vasculitis

Additional clinical history: Woman in acute heroin withdrawal who also has bilateral lower extremity weakness.


Findings:

Brain MRI shows restricted diffusion within the bilateral parietal and occipital lobes as well as over the motor cortex of the frontal lobes bilaterally, left greater than right. T2 prolongation is noted in all the locations where restricted diffusion is seen. Coronal and sagittal reformatted CTA images show areas of subtle beaded appearance of arteries, with focal narrowing and dilatation.


Diagnosis: Multiple bilateral infarcts secondary to IV drug abuse-related cerebral vasculitis


Key points

Increased T2 signal lesions with restricted diffusion have a broad differential
Clinical history, distribution (vascular territories involved, unilateral vs. bilateral), number (single vs. multiple), the presence or absence of mass effect, and the presence or absence of a peripheral ring or central necrosis are key diagnostic clues.
Abscesses may be single or multiple, may be unilateral or bilateral, often have a peripheral ring, and often display mass effect.
Tumors often have mass effect, often have a peripheral ring, may be single or multiple, may be unilateral or bilateral, and may show central necrosis.
Hemorrhage is often in the subdural or subarachnoid space, but may be intraparenchymal, especially if there is history of head trauma or associated fracture.
In acute infarct, there is no mass effect, no peripheral ring, and no central necrosis and the lesions are usually in a single vascular distribution and are usually- but not always- unilateral.
Examples of bilateral acute infarcts, as seen in this patient (note multiple bilateral lesions without mass effect, peripheral ring or central necrosis), are watershed infarcts occurring in typical watershed zones and infarcts occurring secondary to cardiac emboli or vasculitis, both of which are not distributed with respect to single vascular territories (as in this patient).
Besides IV drug abuse (as in this patient), cerebral vasculitis with secondary infarct can be seen in bacterial meningitis, tuberculous meningitis, viral, mycotic, syphilitic or post radiation arteritis, cell mediated arteritis, collagen vascular disease, sarcoid, Wegener's granulomatosis, and Moyamoya disease.