Anterior Canal BPPV

𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: Although the anterior canal (AC) variant of benign paroxysmal positional vertigo (BPPV) is rare, mainly owing to its orientation relative to gravity (which makes otoconial debris much less likely to enter it), it can occur. Because of the relatively para-sagittal orientation of the AC (more so than the posterior canal), in a patient with AC BPPV, nystagmus may be provoked by the right or left Dix-Hallpike maneuvers, as well as with straight head hanging, as it was in this particular patient. A right Dix-Hallpike maneuver will stimulate the right posterior canal (PC) as well as the left AC. This patient was diagnosed with left AC BPPV - left AC excitation causes stimulation of left superior rectus and right inferior oblique muscles, initiating an upward and torsional (towards right ear) slow phase. This generates downward-torsional (towards left ear) fast phases, as seen here. She was treated with repositioning maneuvers, but there was no response in the office. Her neurologic and ocular motor/vestibular examinations were otherwise unremarkable, and when she returned 1 week later, the positional nystagmus had spontaneously resolved. ; Alternatively, there are some patients who may have otoconia in the distal, non-ampullary arm of the PC. If this is the case, it may be possible to produce an inhibitory pattern of nystagmus, so that some cases labelled as AC BPPV may actual be an atypical variant of PC BPPV. This possibility could not be ruled out in her case. 𝗡𝗲𝘂𝗿𝗼-𝗼𝗽𝗵𝘁𝗵𝗮𝗹𝗺𝗼𝗹𝗼𝗴𝘆 𝗮𝗻𝗱 𝗡𝗲𝘂𝗿𝗼-𝗼𝘁𝗼𝗹𝗼𝗴𝘆 𝗧𝗲𝘅𝘁𝗯𝗼𝗼𝗸 𝗟𝗲𝗴𝗲𝗻𝗱: Although the anterior canal (AC) variant of benign paroxysmal positional vertigo (BPPV) is rare, mainly owing to its orientation relative to gravity (which makes otoconial debris much less likely to enter it), it can occur. Because of the relatively para-sagittal orientation of the AC (more so than the posterior canal), in a patient with AC BPPV, nystagmus may be provoked by the right or left Dix-Hallpike maneuvers, as well as with straight head hanging, as it was in this particular patient. A right Dix-Hallpike maneuver will stimulate the right posterior canal (PC) as well as the left AC. This patient was diagnosed with left AC BPPV-left AC excitation causes stimulation of left superior rectus and right inferior oblique muscles, initiating an upward and torsional (toward right ear) slow phase. This generates downward-torsional (toward left ear) fast phases, as seen here. She was treated with repositioning maneuvers, but there was no response in the office. Her neurologic and ocular motor/vestibular examinations were otherwise unremarkable, and when she returned 1 week later, the positional nystagmus had spontaneously resolved. Alternatively, there are some patients who may have otoconia in the distal, non-ampullary arm of the PC. If this is the case, it may be possible to produce an inhibitory pattern of nystagmus, so that some cases labeled as AC BPPV may actual be an atypical variant of PC BPPV. This possibility could not be excluded in her case https://collections.lib.utah.edu/ark:/87278/s6hq7wmw. (Video courtesy of Dr. Marco Mandala)