Positional vertigo gets triggered by a certain critical position of head of the patient. It can be caused by a pathology of central or peripheral component of the vestibular system and nerves. It’s of utmost importance to find out the site of lesion to initiate proper treatment. Hallpike maneuver or Dix-Hallpike maneuver helps to differentiate between positional vertigos caused by peripheral pathology (lesion is in the labyrinth or vestibulo-cochlear nerve) from those due to central lesion (in the cetral nervous system).
The following chart clearly shows how to distinguise these two types based on the results of Dix-Hallpike maneuver. Students need to carefully observe for the findings and correlate them with their physiology and pathology knowledge to reach the correct diagnosis. Look for the following when performing this test on a patient –
|Latency||The signs start after 2 to 20 seconds of reaching the critical position||Signs start as soon as the critical position is reached|
|Duration||Typically lasts for less than 1 minute||Lasts for as long as the position is maintained|
|Fatigability||Fatigable, i.e. duration reduces on successive attempts to elicit the signs and after sufficient number of times it disappears altogether||Non-fatigable|
|The direction of the nystagmus||Always in one direction (the direction depends on the side affected)||Direction varies according to the test position.|
A. Dix-Hallpike maneuver is also called Hallpike Maneuver, Dix-Hallpike test, Positional test. Different textbooks use different terms – so it’s better to remember all of them.
B. Benign paroxysmal positional vertigo is the most common peripheral cause of vertigo. Other causes include Ménière disease, vestibular neuronitis, labyrinthitis, herpes zoster, acoustic neuroma etc.
C. Central causes of positional vertigo may be due to multiple sclerosis, vertebrobasilar insufficiency, increased intracranial pressure, brainstem stroke, or tumor in the fourth ventricle, cerebellum, temporal lobe etc.
Dr. Arnab Mukherjee