Vestibular type of Mondini anomalies with BPPV and Meniere's disease-like symptoms.

An extremely rare case with labyrinthine anomaly with normal hearing was demonstrated. This case firstly showed transient positioning vertigo like benign paroxysmal positional vertigo (BPPV) and subsequently episodic vertigo like Meniere's disease. A 55-year-old male attended our hospital, complaining of transient but persistent positioning vertigo in 2004. The apogeotropic positioning nystagmus was observed in spine position. In 2005, he came to feel episodic vertigo continuously for more than 30min like Meniere's disease. We examined CT scan and 3D-MRI, indicating the hypoplastic lateral semicircular canal (L-SCC) fused together with enlarged vestibule on the left side. We finally diagnosed this case as Mondini anomaly on the left side. The imaging analysis is the most useful for differential diagnosis of Mondini anomalies, because symptoms in these patients are actually various due to the individual inner ear condition. The mechanism of generation of BPPV-like vertigo: the otolith in deformed utricle might be transferred into the fused space with vestibule and L-SCC, resulting in the irrigation of the hypoplastic cupula. The mechanism of generation of Meniere's disease-like vertigo: neuro-otologic findings with furosemide test implied endolymphatic hydrops on the left side. Meniere's disease-like episodic vertigo could be due to subsequently generated endolymphatic hydrops.