Cranial Nerve 8 vs. Cerebellar Injury

Traumatic Brain Injuries (TBI) are very common in any head injury.

Even relatively minor impacts can affect the cranial nerves.

This causes a host of symptoms su dizziness and confusion.

Performing Cranial Nerve VIII correctly will help determine whether a person has a vestibular or cerebellar problem.

CN VIII

The vestibulocochlear nerve is also known as Cranial Nerve VIII.

Cranial Nerve VIII has two components.

The cochlear component that tests for hearing loss and the vestibular component which tests for balance.

When examining a patient with a head injury, first test balance with a patient standing with their eyes open. If they sway or start to fall, they have a cerebellar problem.

Cerebellar problems occur when people hit the back of their head, such as in whiplash injuries.

Testing Cerebellar Function

If this is the case, test the patient by having them perform the following:

Finger to nose test
Rapidly alternate their hands (diadochokinesis)
Heel to shin
Tap their feet
If there is a problem performing any of these tests, suspect a cerebellar disorder.

Testing Vestibular Function

If they do not sway, have them close their eyes and stand. (Rhomberg’s test)

If they sway during Rhomberg’s test, suspect a dorsal column medial lemniscus (DCML) or the vestibular portion of the cochlear nerve.

To determine of there is a DCML lesion, have the person lie supine and use a 129 Hz tuning fork to stimulate the big toe on each foot. (Vibration is the first symptom of DCML lesion)

Then, test 2-point discrimination.

If these tests are negative, suspect a vestibular problem.

Vestibular diagnosis can be made by performing the Hall-Pike maneuver or chair spin test.

If necessary, make a referral to a neurologist for further testing. Some states allow DC’s to do vestibular-occulo-nystagmus testing (VONT) while others do not.

For personal injury (PI) cases, it is important to document any permanent findings and render an impairment rating for any permanent residuals.

If you do not know how to perform an impairment rating, you can learn by taking my 8-hour online course.