Odor perception in temporal lobe epilepsy patients with and without temporal lobectomy

Area of Science:

• Neuroscience
• Olfactory research

Background:

• Olfactory processing is complex and relies on temporal lobe structures.
• Temporal lobe epilepsy (TLE) can affect cognitive functions, including olfaction.
• Surgical resection of the temporal lobe may further impact olfactory abilities.

Purpose of the Study:

• To investigate olfactory detection, memory, and identification in patients with unilateral anterior temporal lobe resection (TLR) and unoperated TLE.
• To compare olfactory performance with a shape memory task.
• To determine the specific effects of TLE and TLR on olfactory function.

Main Methods:

• Monorhinic (single nostril) olfactory testing.
• Odor detection, memory, and identification tasks.
• Shape memory task for comparison.
• Comparison between patients with unilateral anterior TLR (N=16), unoperated TLE (N=18), and healthy controls.

Main Results:

• Lobectomy patients showed normal absolute olfactory sensitivity but impaired odor recognition memory ipsilateral to the resected lobe.
• Odor identification was impaired ipsilaterally and, to some extent, contralaterally in TLR patients.
• Unoperated TLE patients showed bilateral odor identification deficits.
• Both patient groups had deficits in shape recognition memory.

Conclusions:

• Temporal lobe epilepsy alone impacts olfactory information processing.
• Temporal lobe resection exacerbates olfactory deficits, particularly on the side of surgery.
• Olfactory deficits in TLE patients are partly due to the epilepsy and partly due to the surgical intervention.