During a cranial nerve examination, the doctor will carry out a number of simple tests to assess the function of the 12 cranial nerves. The tests do not involve any complex equipment or needles and they are normally performed while you are sitting in a chair. Your sense of smell will be tested using a strong aroma and your hearing will be assessed with a tuning fork. The doctor will check your eyesight, eye movements and look at the back of your eyes through a hand-held optical instrument. You will also be asked to move the muscles in your face, neck, shoulders and tongue.
Before carrying out a cranial nerve examination, doctors should ask for your consent to a physical examination and should wash their hands. Although the cranial nerve exam can be carried out in any order, doctors may begin with the first cranial nerve, the olfactory nerve, which controls the sense of smell. A strong scent such as coffee is held under each nostril in turn and you will be asked whether you can smell it.
In the next part of the cranial nerve examination the optic nerve may be tested. The doctor will ask you to read letters on a chart, to look at near and far objects, and will check your pupils by shining a pen light into your eyes. You will also be asked to look straight ahead while the doctor wiggles a finger at the edges of your field of view to see if you can detect it. Finally, the doctor will examine the backs of your eyes using a small instrument called an ophthalmoscope.
Several of the cranial nerves control eye movements, so you will need to follow the movements of a finger with your eyes and to say if you experience any double vision. Part of the cranial nerve examination assesses the fifth, or trigeminal, cranial nerve, which controls chewing muscles and sensation in the face and eyes. You will be asked to clench your teeth and move your jaw against pressure from the doctor's hand. Cotton wool will be stroked on the skin of your face and gently dabbed in the corner of each eye. The doctor should warn you about this first.
Facial movements are controlled by the seventh, facial cranial nerve. To test this during the cranial nerve examination, the doctor might ask you to lift your eyebrows, screw up your eyes, bare your teeth and puff out your cheeks. In order to assess hearing, which relates to the eighth cranial nerve, a tuning fork will be sounded and placed first behind your ears, then beside each ear. The doctor will ask which of these positions sounds louder and will place the tuning fork in the center of your forehead to determine if it sounds louder in either ear.
In order to test the remaining cranial nerves, you will be asked to stick out your tongue, say "aah" and shrug your shoulders and turn your head against pressure from the doctor's hands. If any problems are found, the doctor may wish to carry out a more detailed neurological examination. You may be referred for further neurology procedures and tests such as CT and MRI scans.
