Although taste is not typically assessed during a routine neurological examination, the 7th nerve does supply taste to the anterior two-thirds of the tongue and hard and soft palates. This can be tested using salty, bitter, sour or sweet solutions.
- the tongue is protruded and held gently by the examiner.
- a small sample of solution is applied to one side of the anterior two-thirds of the tongue using a cotton tipped applicator saturated with the solution.
- with the tongue still protruded, the patient should be asked to point to a sign displaying one of the four possible tastes.
- the patient is then given a small sip of water and the test is repeated using an alternate stimulus.
- the reason the tongue is maintained protruded is because if the patient were allowed to put their tongue back in their mouth in order to verbalize their response, they could masticate and transfer the stimulus to the opposite side which could be affected if there was a lesion of the 7th nerve.