Abstracts

Rationale: Phantosmia is a rare condition in which a nonexistent odor is perceived. Phantosmia is most often associated with psychological disorders such as schizophrenia and mood disorder. Phantosmia due to neurological conditions include temporal lobe epilepsy (TLE), Parkinson s disease, migraines, certain brain tumors involving olfactory system, stroke, traumatic brain injury, and Alzheimer s disease. Upper respiratory infection is also reported to have phantosmia. Isolated phantosmia without above diagnosis is very rare. Here we are reporting three cases phantosmia without associated psychiatric or neurological diagnoses and their favorable response to treatment with lamotrigine. Methods: Retrospective chart review was conducted. All patients had long term ambulatory EEG monitoring and MRI of the brain. Treatment response wais analyzed.Results: We identified three patients (age range 58-65) presenting specifically with phantosmia, intermittently associated with other subjective symptoms. There was no history of episodes consistent with complex partial or generalized seizures. There was no evidence of any psychiatric diagnosis. All patients were without risk factors for epilepsy. Diagnostic evaluations included MRI with coronal T2/FLAIR sequences and prolonged EEG were nonrevealing in all three patients. All patients experienced significant improvement to lamotrigine monotherapy. The response was almost immediate after starting of lamotrigine treatment. (See table for detail). Conclusions: We present a series of three patients with cryptogenic phantosmia presenting during adulthood. Though diagnostic evaluation was nonrevealing, the treatment response to lamotrigine argues for potential simple partial seizures. Olfactory phenomena can represent a manifestation of TLE, but most published series describe either other clinical features consistent with epilepsy or abnormalities on neuroimaging. Further follow up studies on the potential evolution of isolated phantosmia and studies specifically attempting to distinguish between isolated phantosmia and clear TLE are needed.