Head Trauma, Inner Ear and the Perilymph Fistula
Dizziness, vertigo, tinnitus or hearing loss can result from traumatic brain injury or head trauma, neck, temporomandibular joint or inner ear. These symptoms of pain or dysfunction can result from the acceleration-deceleration motion of a motor vehicle collision.
Usually, these symptoms are temporary and short-term. However, persistent dizziness, vertigo, hearing loss or tinnitus lasting more than a few weeks—or in some cases for months and even years—can point to an injury to the inner ear such as a perilymphatic fistula (PLF), which can be difficult to diagnose and treat.
The inner ear consists of a complex series of tubes, called the “bony labyrinth,” that run through the temporal bone of the skull. The tubes are filled with perilymph fluid. Within the bony tubes and perilymph fluid are a second series of tubes made out of delicate cellular structures, called the “membranous labyrinth.”
If the bony capsule of the inner ear is perforated, by either a rupture of the ligamentous attachment of the stapedial footplate to the bone of the oval window or the round window membrane, then the perilymph fluid leaks out of the inner ear, producing a vestibular disturbance and/or hearing loss. This is known as perilymphatic fistula (PLF). There are several possible places where the fluid-filled inner ear can be perforated: (1) between the air-filled middle ear/mastoid sinus, (2) into the intracranial cavity, or (3) into other spaces in the temporal bone. In most cases, the opening results from a tear or defect in one or both of the small, thin membranes between the middle and inner ears (the “oval window” and the “round window”).
In addition to dizziness, vertigo, imbalance, nausea, and vomiting, individuals with PLF most commonly report experiencing an unsteadiness that increases with activity and is relieved by rest. Some people experience ringing or fullness in the ears and others notice hearing loss. Others report worsened symptoms with coughing, sneezing, laughing or other exertion.
PLF is assessed by differential diagnoses processes that eliminate more readily identifiable causes for vestibular dysfunction or hearing loss. Physical examination can include the following tests: (1) Romberg (feet together); (2) tandem Romberg (heel to toe); (3) Fukuda stepping test; (4) fistula tests (Hennebert sign) whereby positive and negative pressure is applied to the intact eardrum with a pneumatic otoscope to elicit nystagmus or disequilibrium; and (5) Singleton eyes-closed turning tests. Positive nystagmus and benign paroxysmal positional vertigo are often associated with traumatic PLF. Sensorineural hearing loss may be confirmed by audiograms or electronystagmography (ENG) tests to assess the vestibular system. A CT scan or MRI may be indicated following head trauma if temporal bone fracture is considered, but those imagings are inadequate to evaluate the round and oval window regions. If you suspect that a patient may have PLF, a referral to an otologist/neurologist is appropriate.
The surgery to repair PLF is accomplished by entering the ear canal with an operative microscope. The surgeon elevates the tympanomeatal flap to expose the oval and round windows for careful inspection for a possible perilymph fistulous site. The surgeon then covers both windows with soft tissue harvested from an endaural incision site, and applies fibrin glue before repositioning the tympanomeatal flap. Patient responses to this procedure are overwhelmingly positive.
As noted above, trauma to the brain or neck from a motor vehicle collision is a common cause of PLF. In one PLF case study, between 30 and 60 percent of the cases were caused by head trauma. According to dizziness and vertigo specialist, otologist/neurologist Dennis Fitzgerald, MD, “It cannot be determined how many cases [of post head trauma PLF] go undiagnosed. Alerting physicians to the existence of this disorder, however, will help reduce the number of undiagnosed cases.” Dr. Fitzgerald recommends these maxims for diagnosing PLF in the head trauma patient:
- Beware of spontaneous-episodic or fluctuating vertigo/dizziness as an indication of PLF.
- If fistula tests are negative, give the patient 6 months to recover. If significant dizziness persists, consider treating for PLF.
- If there is hearing loss, especially unilateral, look for PLF.
- Consider fistula tests of any kind as indicators of an active PLF.
- PLFs may intermittently open and close and give variable results on diagnostic tests.
- ECOGs with SP/AP ratios of .40 to .60 may indicate a PLF causing a mild secondary endolymphatic hydrops. 3
The attorneys at Adler Giersch, PS stay current on medical research that impacts our understanding of trauma as it allows us to be better advocates on behalf of our clients. Effective and tough advocacy happens best when we connect the medical and legal worlds on behalf of those with traumatic injuries caused by the negligence or recklessness of others. If we can assist with a complimentary consultation, simply give us a call.