The impact of transparency on hemispheric lateralization of idiom comprehension: An rTMS study.

Previous neuropsychological data have equivocal suggestions concerning hemispheric involvement during idiom comprehension. The possible contribution of idioms transparency to the lateralization of figurative language comprehension has not been investigated using an interference technique. To analyse the cortical lateralization of idiom transparency processing, we employed inhibitory repetitive transcranial magnetic stimulation (rTMS) to the left and right dorsolateral prefrontal cortex (DLPFC) during the processing of opaque idioms, transparent idioms, and non-idiomatic literal phrases. Based on the Coarse Semantic Coding theory, we predicted a greater right hemisphere involvement when processing opaque than transparent idioms. Eighteen young healthy participants underwent rTMS pulses at 1 Hz frequency, 110% of motor threshold intensity for 15 min (900 pulses) in two sessions at one-week intervals. In a semantic decision task, participants judged the relatedness of an idiom and a target word. The target word was figuratively or literally related to the idiom, or unrelated. The study also included non-idiomatic sentences. We found that left DLPFC functions are more critical for comprehension of opaque rather than transparent idioms when referring to the figurative associations of the idioms. Opaque idioms, in the context of their figurative meaning, rely more heavily on left hemisphere resources. This finding suggests that opaque idioms are seemingly processed as one unit. Taken together, we believe that the transparency of idiomatic expressions may play an important role in modulating hemispheric functions involved in figurative language processing.

Episodic Oculomotor Nerve Palsy with Intracranial Hypertension and Carcinomatous Meningitis.

The classically affected cranial nerve from intracranial hypertension is the sixth nerve. Carcinomatous meningitis can cause persistent or progressive cranial nerve palsies by infiltrating them in the subarachnoid space. Here we present a rare case of episodic, short-lasting, and unilateral oculomotor nerve palsy associated with carcinomatous meningitis and intracranial hypertension in a 44-year-old woman diagnosed with metastatic lung adenocarcinoma. As the survival rates enhance for metastatic cancers, neurologists should expect more perplexing neurologic presentations and consider leptomeningeal metastasis and intracranial hypertension in patients who have cancer and present with short episodes of diplopia and unilateral third nerve palsy.