1) The document reports on a study of 132 patients with horizontal canal benign paroxysmal positional vertigo (HC-BPPV) treated with barbecue maneuver, forced prolonged position (FPP), and/or rapid head rotation. 2) Results found that barbecue maneuver and/or FPP resolved HC-BPPV in 22 patients, while rapid head rotation resolved HC-BPPV in 7 patients, inducing different nystagmus responses. 3) The document concludes that FPP and barbecue maneuver remain first choice treatments for HC-BPPV, while rapid head rotation can be used for intractable cases, especially cupulolithiasis cases. Nystagmus direction depends on

1. 方向變換性逆地型眼振之可能機轉 Possible Mechanism of Direction-Changing Apogeotropic Nystagmus 署立新竹醫院耳鼻喉科 葉大偉 醫師

2. Patients and methods Time ： from March 2007 to March 2008 Patients ： 132 BPPV patients were treated in our hospital Dix-Hallpike manauver 、 head roll test was done for the diagnosis of PC-BPPV and HC-BPPV. All HC-BPPV patients were treated with barbecue maneuver and/or FPP(Forced Prolonged Position). Intractable cases were treated with rapid head rotation. The patients were followed up 2 days later , complete resolution was considered if no further positional vertigo reported for 1 month after the last treatment .

3. Result HC-BPPV(41) HC-Can(24) HC-Cup(17) Barbecue and/or FPP(22) RHR(2): no Nystagmus(1) atypical Nystagmus(1) FPP(10) RHR(7): geotrophic Nystagmus(3) no Nystagmus(2) atypical Nystagmus(2)

4. A single therapy for all subtypes of horizontal canal positional vertigo. Laryngoscope. 2005 Aug;115(8):1432-5 Chiou WY , Lee HL , Tsai SC , Yu TH , Lee XX .

6. A case of HC-BPPV,FPP to R‘t was advised in other hospital. 96.11.30: apogeotrophic N.(L’t side stronger) after rapid head shaking =>apogeotrophic N.(R’t side stronger) repeat rapid head shaking =>no nystagmus, no vertigo 96.12.3: Dix-Hallpike maneuver:counter-clockwise N. Imp:PC-BPPV,Rt Epley maneuver was done 96.12.5: no vertigo after Epley maneuver

7. Attached phase

8. Detached phase

9. Discussion HC-BPPV:HC-Can :canalithiasis HC-Cup :cupulolithiasis Cup-U :utricle side of cupulolithiasis Cup-C: canal side of cupulolithiasis Why geotrophic N. in HC-Can? Why apogeotrohic N. in HC-Cup? Why stronger N. side ALWAYS lesion side in HC-Can? Why stronger N. side NOT ALWAYS lesion side in HC-Cup? Why actually FPP is available in all HC-Can?

12. Conclusion FPP and/or barbecue maneuver still the first choice for HC-BPPV. Failure of FPP may be due to misdiagnosis of lesion side. Rapid head rotation can be used in intractable cases of HC-BPPV , especially in HC-Cup. Nystagmus may be evoked changed according to the balance between the effect of Ewald’s law and the amount of otoliths detached from cupula.

13. The End