In particular, this pattern is seen with bilateral frontal subcortical white matter involvement and is most likely due to a disconnection syndrome. Bradyphrenia and bradykinesia are commonly seen in this form of memory loss. Ideomotor apraxias are not commonly seen with non-dominant parietal damage but imply, rather, an insult in the dominant inferior parietal, temporal, or frontal lobes. The lesion may be cortical or subcortical, and is due to a disconnection between language comprehension and motor output. The homonymous hemianopsia implies a lesion involving the optic radiations in the subcortex of the parietal and temporal lobes, or occipital cortex.
Macular involvement places the lesion in the optic radiations.
A single parietal insult would be expected to produce only an inferior quadrantanopsia. One might also consider an unusual presentation of a butterfly glioma or other CNS tumor, such as lymphoma. This patient also complained of generalized pruritis which may be seen in several conditions, including hyperthyroidism, diabetes mellitus, carcinoid syndrome, lymphoma, leukemia, abdominal cancer, some CNS tumors, multiple myeloma, mycosis fungoides, drug ingestion, scabies, onchocerciasis, ascariasis, chronic renal failure, polycythemia vera, paraproteinemia, cholestasis, pregnancy, psychogenic states, and HIV infection. The diagnosis most consistent with the clinical features and widespread demyelination seen on MRI is PML, which has a predilection for the white matter of the parietal and occipital lobes. When confronted with his diagnosis, the patient revealed that he engaged in unprotected sex with several prostitutes in Southeast Asia on his trip six years previously.