Benign paroxysmal positional vertigo overview

# Overview
BPPV was first dicribed by Adler and Barany, who described it as a problem in the otolith organs. In 1952, Margaret Dix and Charles Hallpike named it positional nystagmus of the benign positional type and noticed nystagmus and vertigo with different headmovements. It is understood that BPPV is the result of free floating calcium carbonate crystal formation (canalolithiasis) inside the semicircular canals and Movement of these otoconia with head movement will result in inappropriate stimulation of hair cells following movement of the endolymph. According to which semicircular canal the otoconia have migrated to into 3 subtypes including posterior semicircular canal BPPV, lateral semicircular canal BPPV, and superior (anterior) semicircular canal BPPV.  Common causes of BPPV may include age related degeneration of the vestibular system, and head trauma.  The diagnostic study of choice for BPPV is patient history and observing nystagmus on Dix-Hall pike maneuver and in most of the cases treatment is Epley maneuver.

# Historical Perspective
BPPV was first dicribed by Adler and Barany, who described it as a problem in the otolith organs. In 1952, Margaret Dix and Charles Hallpike named it positional nystagmus of the benign positional type. They noted nystagmus and vertigo with different headmovements. Hallpike also defined it as a peripheral problem rather than central (brain) problem. In 1962 Harold Schuknecht described theory of detached utricular otoconia (cupulolithiasis). Hall et al and Epley described the theory of free floating particle (canalithiasis). The first treatment strategy suggested for BPPV treatment was cawthorne's exercise (repeatitive head movement which cause vertigo in order to reach central adaption). The newest treatment strategy is to perform Dix Hallpike test to diagnos and induce the vertigo and then performing CRP (Epley) maneuver.

# Classification
Benign paroxysmal positional vertigo may be classified according to which semicircular canal the otoconia have migrated to into 3 subtypes including posterior semicircular canal BPPV, lateral semicircular canal BPPV, and superior (anterior) semicircular canal BPPV.

# Pathophysiology
It is understood that BPPV is the result of free floating calcium carbonate crystal formation (canalolithiasis) inside the semicircular canals. Movement of these otoconia with head movement will result in inappropriate stimulation of hair cells following movement of the endolymph. In some studies it was demonstrated that people with BPPV in their first degree family are at more risk of development of the disease themselves. One of the theories behind the familial aspect of BPPV is that these families might have less adhesive gelatinous matrix of the utricular macula which predisposed them to BPPV. On microscopic histopathological analysis, crystals with combination of a gelatinous matrix and calcium carbonate are characteristic findings of otoconia in BPPV.

# Causes
Common causes of BPPV may include age related degeneration of the vestibular system, and head trauma. Less common causes of BPPV include ear surgery, and prolong positioning on the back (in dentist chair).

# Differentiating benign paroxysmal positional vertigo from Other Diseases
BPPV must be differentiated from other diseases that cause vertigo, nystagmus, and hearing problems, such as vestibular neuritis, HSV oticus, Meniere disease, labyrinrhine concussion, perilymphatic fistula, semicircular canal dehiscence syndrome, vestibular paroxysmia, Cogan syndrome, vestibular schwannoma, otitis media, aminoglycoside toxicity, recurrent vestibulopathy, vestibular migraine, epileptic vertigo, multiple sclerosis, brain tumors, cerebellar infarction/hemorrhage, brain stem ischemia, chiari malformation, and Parkinson.

# Epidemiology and Demographics
The incidence of BPPV is approximately 107 cases per 100,000 individuals worldwide. The prevalence of BPPV is approximately 65 per 100,000 individuals worldwide. Idiopathic BPPV commonly affects individuals older than 50 years of age. BPPV following head trauma can happen in younger ages. women are more commonly affected by BPPV than men. The women to men ratio is approximately 2 to 1.

# Risk Factors
Common risk factors in the development of BPPV include hyperlipidemia, hypertension, smoking, diabetes mellitus, thyroid dysfunction, general anesthesia, advanced age, female gender, and yoga.

# Screening
There is insufficient evidence to recommend routine screening for BPPV.

# Natural History, Complications, and Prognosis
If left untreated, almost 100% of patients with BPPV may experience spontaneous recovery. Common complications of BPPV include nausea, vomiting, fainting, canal conversion, and cervical spine and neurological complications following Dix Hallpike or Epley maneuvers. Prognosis is generally excellent, and almost always BPPV will resolve over days to weeks on its own even without maneuvers or medications.

# Diagnosis

## Diagnostic Study of Choice
The diagnostic study of choice for BPPV is patient history and observing nystagmus on Dix-Hall pike maneuver.

## History and Symptoms
The hallmark of BPPV is recurrent brief positional vertigo. A positive history of hyperlipidemia, hypertension, smoking, diabetes mellitus, thyroid dysfunction, general anesthesia, advanced age, female gender, and yoga is suggestive of BPPV. The most common symptoms of BPPV include positional vertigo, imbalance, nausea and vomiting.

## Physical Examination
Physical examination of patients with BPPV is usually remarkable for balance problems and nystagmus on Dix-Hall pike maneuver.

## Laboratory Findings
There are no diagnostic laboratory findings associated with BPPV.

## Electrocardiogram
There are no ECG findings associated with BPPV.

## X-ray
There are no x-ray findings associated with BPPV.

## Echocardiography and Ultrasound
There are no echocardiography/ultrasound findings associated with BPPV.

## CT scan
There are no CT scan findings associated with BPPV, but If patients doesn't respond to treatment or doesn't show the typical nystagmus on Dix-Hall pike maneuver, we may use CT scan in order to rule out other abnormalities.

## MRI
There are no MRI findings associated with BPPV, but If patients doesn't respond to treatment or doesn't show the typical nystagmus on Dix-Hall pike maneuver, we may use MRI in order to rule out other abnormalities.

## Other Imaging Findings
There are no other imaging findings associated with BPPV.

## Other Diagnostic Studies
There are no other diagnostic studies associated with BPPV, but If patients doesn't respond to treatment or doesn't show the typical nystagmus on Dix-Hall pike maneuver, in order to rule out other abnormalities we may perform some additional test such as electronystagmography (ENG) or video nystagmography (VNG) and audiometry.

# Treatment

## Medical Therapy
Pharmacologic medical therapy is recommended among BPPV patients who does not answer well to Epley maneuver and continue to have multiple vertigo attacks which reduces their quality of life. Preferred regimen Betahistine 24 mg PO q12h for 7 days.

## Interventions
The mainstay of treatment for BPPV is office maneuvers. For posterior canal BPPV we perform Epley maneuver or Semon maneuver. For horizental canal BPPV we perform Lempert roll maneuver. For superior canal BPPV we perform Epley maneuver.

## Surgery
Surgery is not the first-line treatment option for patients with BPPV. Surgery is usually reserved for patients with refractory BPPV. The surgery options include transection of the posterior ampullary nerve, argon laser (inducing ossification of the posterior canal) and surgical occlusion of the posterior canal with bony plugs. Since hearing loss is one of the most important complications of these procedures, hearing problem in the other ear is contraindication for surgery.

## Primary Prevention
Effective measures for the primary prevention of BPPV is preventing the modifiable risk factors from happening such as hyperlipidemia, hypertension, smoking, diabetes mellitus, general anesthesia, and yoga.

## Secondary Prevention
There are no established measures for the secondary prevention of BPPV.