Various functional tests are available to examine the brain and nerves, such as tests of motor function or sensitivity. We explain below which tests are available and what is done during them.
Functional tests: cranial nerves
The twelve paired cranial nerves are important structures that connect the brain to the periphery. They contain various nerve fibers that are responsible for muscle movement, sensory perception, and other sensations, and travel to the face (eyes, ears, nose, mouth, among others), neck, and chest and abdominal organs.
Their function can be assessed by the following tests and examinations, among others:
- Eye tests
- Ear examinations
- Testing of skin sensitivity in the face, facial expressions and tongue movement.
These are checked when the doctor asks you, for example, to show him your tongue, frown and look behind his fingers.
Functional test of motor skills
For the ability to move voluntary muscles in a targeted and coordinated manner, the brain, spinal cord, peripheral nerves and muscles must coordinate. Therefore, quite different tests are also used for motor function testing.
- Coordination: during normal walking or even tightrope walking, standing with eyes closed, on tiptoes and heels, or virtually twisting in a light bulb, the coordinated interaction is checked. This can be impaired in very different disorders such as Parkinson’s disease or inner ear damage.
- The doctor asks the patient to tense individual muscles or muscle groups against his resistance. He always assesses the strength in a side-by-side comparison and also pays attention to pain. Holding the arms out in front of him with his eyes closed can also give indications of slight disturbances – namely, when one arm slowly sinks.
- The state of tension of the muscles also gives important clues to possible diseases. It may be increased (spasticity, rigor), for example, in Parkinson’s disease or decreased, for example, in muscle diseases.
- Reflexes: Almost everyone knows it: the rubber-covered, shiny little hammer with which the doctor hits under the knee or in the crook of the elbow, causing the leg or arm to twitch. He uses it to test how well a stimulus is transmitted to the muscle via nerve fibers. Reflexes can be reduced, extinguished or increased (clonus). Since the stimulus response varies from individual to individual, reflexes are always assessed in a side-by-side comparison. Strong differences are most likely pathological. In addition, there are reflexes that are normal in babies, but then pathological later.
Sensitivity test
The examination of the different qualities of sensation is also carried out in a side-by-side comparison. One after the other, with eyes closed, the patient is given different stimuli – first on healthy areas to compare how it feels normal, then on the presumably diseased areas.
Tested are:
- Touch sensation (for example, with a cotton ball).
- Vibration sensation (with a tuning fork placed on bony prominences).
- Position and movement sensation (“what is up and down” with the finger moved by the doctor).
- Pain sensation (with a broken wooden stick) and.
- Temperature sensation (with cold and warm water in a test tube).
In addition, the patient should recognize numbers written on the skin, feel or grasp objects, and recognize when two stimuli are applied simultaneously. Disturbances in sensitivity occur, for example, in the case of a herniated disc or nerve disorders resulting from diabetes.
