Phleboliths.

Benign paroxysmal positional vertigo (BPPV) is a mechanical disorder of the vestibular system in which calcite particles called otoconia interfere with the mechanical functioning of the fluid-filled semicircular canals normally used to sense rotation. Using hydrodynamic models, we examine the two mechanisms proposed by the medical community for BPPV: cupulolithiasis, in which otoconia attach directly to the cupula (a sensory membrane), and canalithiasis, in which otoconia settle through the canals and exert a fluid pressure across the cupula. We utilize known hydrodynamic calculations and make reasonable geometric and physical approximations to derive an expression for the transcupular pressure DeltaPc exerted by a settling solid particle in canalithiasis. By tracking settling otoconia in a two-dimensional model geometry, the cupular volume displacement and associated eye response (nystagmus) can be calculated quantitatively. Several important features emerge: (1) a pressure amplification occurs as otoconia enter a narrowing duct; (2) an average-sized otoconium requires approximately 5 s to settle through the wide ampulla, where DeltaPc is not amplified, which suggests a mechanism for the observed latency of BPPV; and (3) an average-sized otoconium beginning below the center of the cupula can cause a volumetric cupular displacement on the order of 30 pL, with nystagmus of order 2 degrees/s, which is approximately the threshold for sensation. Larger cupular volume displacement and nystagmus could result from larger and/or multiple otoconia.

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PubMed2004

Pseudo bilateral tonsilloliths: a case report and review of the literature.

Tonsilloliths are very rare concretions found in the tonsillar crypt. They are usually single and unilateral, but occasionally may be multiple or bilateral. Small concretions in the tonsils are common, but well formed giant unilateral or bilateral tonsilloliths are extremely uncommon. Only two cases of bilateral tonsilloliths have so far been reported in the literature. A case of unilateral tonsillolith, mimicking bilateral tonsilloliths taken with the orthopantogram (OPT) in a 57-year-old Malaysian Indian female with squamous cell carcinoma of the oral cavity is described. Although the OPT is a reliable and standard panoramic X-ray unit used in dentistry, superimposition of a lesion involving one side of the jaw creates a pseudo or ghost image on the contralateral side leading to a misdiagnosis of bilateral lesions. This report highlights that tonsilloliths, though rare, should be considered in the differential diagnosis of radiopaque masses involving the mandibular ramus, and that investigations such as CT scan or MRI may be required to differentiate pseudo or ghost images from true bilateral pathologies.

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