A case of evolving post-ictal language disturbance secondary to a left temporal arteriovenous malformation: jargon aphasia or formal thought disorder?

INTRODUCTION

Wernicke's dysphasia and formal thought disorder are regarded as distinct diagnostic entities although both are linked to pathology in the left superior temporal gyrus (STG). We describe a patient with focal pathology in the left STG, giving rise acutely to a fluent dysphasia, which gradually evolved into formal thought disorder.

METHOD

Clinical, neuropsychological, neuropsychiatric, and neuroradiological assessment.

RESULTS

A right-handed patient, AJ, presented acutely with a fluent dysphasia. His speech output gradually evolved from undifferentiated jargon, through neologistic jargon, to an intelligible but bizarre form of discourse. Comprehension was relatively well preserved. Radiology revealed an arteriovenous malformation in the left middle, and inferior temporal gyri, with reduced perfusion of the left STG. Six months later his overt dysphasia had recovered, but his speech retained some of its previous characteristics, in particular a tendency to a loose association of ideas which now suggested a disorder of thought.

CONCLUSIONS

AJ's case illustrates that comprehension may be unexpectedly preserved in jargon aphasia, and that an overtly linguistic impairment can gradually evolve to an apparent disorder of thought. Indistinguishable formal thought disorders can result from "structural" and "functional" pathology in the dominant temporal lobe.