Postural control in horizontal benign paroxysmal positional vertigo

Sixteen patients affected by benign paroxysmal positional vertigo of the ho rizontal semicircular canal (BPPV-HSC) were investigated by means of dynami c posturography (DP) and during bithermal caloric stimulation. Data were co mpared to data from 40 patients with benign paroxysmal positional vertigo o f the posterior semicircular canal (BPPV-PSC) and 20 healthy controls. No p ostural deficit was observed before or after a liberative Lempert's manoeuv re when patients were compared to control subjects. BPPV-PSC postural score s were significantly impaired compared to scores from the BPPV-HSC group. A residual significant postural impairment was also observed after a success ful liberative manoeuvre in the BPPV-PSC group. Electronystagmographic reco rdings before recovery revealed significant hypoexcitability of the affecte d ear in 8/16 patients of the BPPV-HSC group. After the liberative manoeuvr e, a symmetric bilateral response to caloric stimulation was recorded in al l patients. Three main conclusions can be drawn from the present data. Firs t, disorders of the horizontal semicircular canal do not change postural co ntrol. Second, dynamic posturography can detect the postural imbalance due to posterior semicircular canal dysfunction even after resolution of paroxy smal vertigo attacks. Third, utricular dysfunction can be ruled out as a ca use of the residual postural deficit observed in BPPV-PSC patients. Therefo re the recovery delay observed even 1 month after the liberative manoeuvre in the BPPV-PSC-group might be due to the persistence of small amounts of r esidual debris in the canal, to paralysis of ampullar receptors, or to the time needed for central vestibular re-adaptation.