electrogustometry

Electrogustometry (EGM) is a psychophysical method for assessing gustatory function by applying controlled electrical stimuli to the oral mucosa, typically the tongue, to determine the sensory threshold for taste. It measures the minimum electrical current that elicits a taste sensation, providing a functional map of gustatory integrity.

Procedure: A small electrode is placed on a designated area of the tongue (commonly the tip or fungiform region) and a reference electrode is placed on the lip or cheek. The device delivers brief current pulses of defined amplitude, frequency, and duration. The current is gradually increased in small steps until the patient reports tasting a sensation; the threshold is recorded. The test can be repeated at multiple tongue regions to generate a regional taste map. Testing conditions, such as saliva, temperature, and patient cooperation, affect results.

Interpretation: Thresholds are compared with normative data or used to detect unilateral or regional loss of taste sensation. Elevated thresholds (hypogeusia) or abnormally low thresholds (hypergeusia) may indicate peripheral nerve, taste bud, or mucosal dysfunction; patterns can help distinguish peripheral from central etiologies. EGM is often used alongside other gustatory tests and in monitoring nerve injury after head and neck surgery or during chemotherapy.

Safety and limitations: EGM uses low-intensity currents and is generally safe when performed by trained personnel, but it can cause discomfort or local irritation. Results are subjective and can vary with technique, electrode placement, and patient response, so findings should be integrated with clinical assessment.