Surgery for Benign Positional Vertigo
Benign Positional Vertigo (BPPV) is a common disorder of the peripheral vestibular system. Typically over 95% of patients afflicted will note resolution of their vertigo with time and/or conservative treatment. For the small group of patients with persistent symptoms, only two surgical options were prevouly available. In the first, the entire affected vestibular system was denervated. In the second only a limited portion was denervated, but good results were obtained by only a few surgeons. Recently a new procedure was introduced by a Canadian otolaryngologist that carried minimal risk, required only a brief hospital stay, and showed good results that have been reproduced by others.
BPPV is one of the most common disorders of the peripheral vestibular system in patients seen in clinics that address balance problems. The name was coined prior to the advent of modern medicine when many patients with vertigo had significant, life-threatening (“malignant”) disorders such as brain tumors. The remainder of the name characterizes the symptoms of the disorder: brief spells (paroxysms) of vertigo experienced with particular head motion or position.
BPPV most commonly arises spontaneously although it can be seen after head trauma or ear surgery. Typically, a patient will note sudden onset of symptoms. Characteristic head positions will induce bursts of vertigo lasting 2-30 seconds. Between spells most patients are asymptomatic. There are rarely any aural complaints. The most common inciting head position is rotation toward the affected ear, especially when in the supine position. Patients tend to fear these positions and quickly learn to avoid them. Many patients will sleep inclined or in an upright position and will avoid lying on the affected side. Some deveolop a complex series of motions to go from upright to supine (or vice cersa) to avoid the particular stimulating posistion.
Evidence strongly suggests that BPPV is an inner ear disorder. The inner ear (labyrinth) is embedded in the temporal bone and contains the organs of both hearing (cochlea) and balance (semicircular canals). The vestibule is an open area between the cochlea and the semicurcular canals that contains two hair cell lined areas believed to be important for position orientation. The microvilli (hairs) of these cells are emedded in a mass of gelatin-like material that contains particles of calcuim carbonate. This mass of gelatin and particles is comtinually being affected by gravity and inertia. The three semicircular canals ( superior, horizontal, posterior) complete about 3/4 of a circle with each end opening into the vestibule. Each canal has an area of sensory epithelia that respond to movenent of fluid within the canal secondary to head motion. The most commonly accepted theory of the etiology of BPPV suggests that some of the calcuim carbonate particles become dislodged and fall back, stimulating the sensory area of the posterior semicircular canal.
On examination the Hallpike maneuver will elicit vertigo. The the patient’s head to one side, he/she is rapidly transferred from a sitting position to a supine position with the head hanging off the edge of the examination table. When the affected ear is towards the floor, the loose particles in the inner ear then float down towards the posterior semicircular canal. The vertigo begins when the particles reach the canal, approximately 1-3 seconds after the maneuver, and will last up to 30 seconds. Rotary nystagmus (uncontrolled eye motion) is usually visible on ocular examination. Symptoms lessen with repetition of the maneuver.
In the majority of paatients (95%) symptoms will resolve completely within six months. Generally, vestibular suppressants such as meclizine (Antivert) or diazepam (Valium) are of little benefit. Head and neck motion in the form of vestibular exercises can sometimes speed recovery. Office manuevers that move the crystals in the inner ear (“particle repositioning maneuvers”) are generally very successful.
Persistent BPPV can significantly interfere with daily activity and daily functioning. The severity of symptoms will determine if surgery is indicated. In the past there were only two surgical options. The first, vestibular neurectomy, involves cutting the balance nerve. Thes is extremely effective but requires entrance into the intracranial space, an extended recovery, and denervation of the entire vestibular system. The second option involves sectioning the nerve exiting from the posterior semicircular canal. Theoretically, this is an ideal surgery, but unfortunately most surgeons have not been able to reprocuce the results that were initially reported.
In 1990, a Canadian otolaryngologist reported a series of patients who had undergone a procedure designated posterior semicircular canal occlusion. This procedure is performed through an incision behind the external ear (auricle). A mastoidectomy is then performed and is required to remove the bone between the scalp and the inner ear. The posterior semiciucular canal is then gently opened and the lumen is obliterated with moist bone particles from the mastoidectomy. The fumction of the canal is then completely eliminatied with preservation of the remainder of the inner ear. A brief hospital stay is usual. Patients are ambulatory immediately after the surgery but generally experience disequilibrium that resolves over several weeks. The positional vertigo is immediately relieved. Although the risk of hearing loss was a major concern initially, it was discovered that, although temporary hearing loss was common, permanent hearing loss was unusual.
Posterior semicircular occlusion has been adapted and utilized at the Michigan Ear Institute with great success. Only a small portion of the people with BPPV are even considered for this surgery, but because the success of this procedure at the Michigan Ear Institute has been excellent, it is an appropriate possiblity for those who may require it.