BACKGROUND AND OBJECTIVES: At the beginning of the Dix-Hallpike maneuver, one of the two functional pair planes of the vertical canals is presumed to lie in the sagittal plane. However, this presumption is not correct. This paper aims to describe this problem more clearly and speculate on clinical implications. Mathematical and theoretical reasoning will be discussed. MATERIALS AND METHODS: Two sets, each composed of three perpendicular planes, were modeled for simplified semicircular canals in the anatomical position with a 3D modeler. After a yaw rotation of 45 degrees, the surface normal of the vertical canal plane is compared with that of the true sagittal plane. RESULTS: The angle between the two normals was approximately 21.1 degrees. The theoretical vertical canal plane did not lie in the sagittal plane at the beginning position of Dix-Hallpike maneuver. CONCLUSIONS: More exact Dix-Hallpike maneuvers may require a roll tilting about 20 degrees toward the affected side.
Semicircular Canals ; Vertigo

Humans ; Semicircular Canals ; abnormalities

A 31-year-old woman presented with the very unusual symptom of being able to hear the movement of her eyeballs in her left ear: “I can hear my eyeballs move!” She initially described hearing a recurrent “swishing” sound that would occur intermittently. She eventually realized that its occurrence coincided with eyeball movement. In the eight months’ duration of her symptom, she had been unable to obtain a diagnosis from physicians whom she consulted and had even been referred for psychiatric evaluation and treatment. An otolaryngologist whom she consulted had a standard pure tone audiometric examination done, and this showed normal hearing acuity in both ears. A Magnetic Resonance Imaging (MRI) of the inner ear and brain likewise showed no abnormalities. Due to the peculiarity of the patient’s complaint, the otolaryngologist consulted with a neurotologist who suspected the presence of a semicircular canal dehiscence. A computerized tomographic imaging study of the temporal bone confirmed the presence of a left superior semicircular canal dehiscence syndrome.
Semicircular Canal Dehiscence ; Semicircular Canals ; Eye Movements

Even though benign paroxysmal positional vertigo (BPPV) mostly affects a single semicircular canal (SCC), BPPV simultaneously involving more than one SCC is not rare. This multi-canal BPPV may either involve the same canals on both sides or simultaneously affect different canals on the same or on both sides. Since the SCCs can be involved in various combinations in one or both ears, multi-canal BPPVs pose diagnostic and therapeutic challenges. The different patterns of nystagmus induced during each positional maneuver should be differentiated from positional vertigo and nystagmus due to central lesions. It remains unknown which canal should be treated first and which maneuver should be adopted for multi-canal BPPVs. Furthermore, the optimal interval from treatment of a canal to another should be determined. The response to canalith repositioning maneuvers and recurrences do not differ between multi- and single canal BPPVs in spite of more frequent involvement of multiple canals in traumatic cases.
Ear ; Recurrence ; Semicircular Canals ; Vertigo

Benign paroxysmal positional vertigo (BPPV) is a commonly presenting problem at the emergency department. Three types have been recognized based on the pathogenesis of BPPV. The first is posterior-canal canalolithiasis, the second is horizontal-canal canalolithiasis, and the last is horizontal-canal cupulolithiasis. With the first two types of BPPV, an otolith-repositioning manuever can be performed quickly at the bedside with rapid results, often providing much satisfaction to both patient and physician. However, in the case of horizontal-canal cupulolithiasis, no established repositioning maneuver existed until recently. In 2000, Jo et al. developed a new repositioning maneuver and reported excellent results. We report a case of BPPV horizontal-canal cupulolithiasis that immediately responded to the maneuver of Jo et al. and strongly recommend use of this repositioning maneuver at the emergency department.
Emergency Service, Hospital ; Humans ; Semicircular Canals* ; Vertigo

The authors report jerky seesaw nystagmus, extorsional downbeating in the right eye and intorsional upbeating in the left eye, in a patient with right internuclear ophthalmoplegia (INO). This pattern of nystagmus may occur by disrupting pathways from contralateral posterior and anterior semicircular canals by a lesion in the medial longitudinal fasciculus. Depending on damage to the pathways from contralateral vertical canals, various patterns of dissociated torsional-vertical nystagmus may accompany INO.
Humans ; Ocular Motility Disorders* ; Semicircular Canals

Paroxysmal positional nystagmus is a common finding in patients with vertigo and can occur in typical and atypical forms. Atypical forms of paroxismal positional nystagmus are thought to represent conditions which are in fact not "benign". This patient was diagnosed as right posterior semicircular canal BPPV at first. After modified Epley maneuver, the type of nystagmus was changed to atypical forms. After left cupulolith reposition maneuver (CRmM), the nystagmus and dizziness were disappeared finally.
Dizziness ; Humans ; Nystagmus, Physiologic ; Semicircular Canals ; Vertigo*

The authors report jerky seesaw nystagmus, extorsional downbeating in the ipsilesional eye and intorsional upbeating in the contralesional eye, in a patient with internuclear ophthalmoplegia (INO) from focal pontine lesion. This pattern of nystagmus may occur by disrupting pathways from contralateral posterior and anterior semicircular canals by a lesion in the medial longitudinal fasciculus. Depending on the pathways involved, various patterns of dissociated torsional-vertical nystagmus may accompany INO.
Humans ; Ocular Motility Disorders* ; Semicircular Canals

PURPOSE: To evaluate three-dimensional volume-rendering of congenital inner-ear malfornations using the MR CISS (Constructive Interference in Steady State) sequence. MATERIALS AND METHODS: MR CISS images of 30 inner ears of 15 patients (M:F=10:5; mean age, 6.5years) in whom inner-ear malfornation was suspected were obtained using a superconducting Magnetom Vision System (Simens, Erlangen, Germany), with TR/TE/FA parameters of 12.25 ms/5.9 ms/70 degree. The images obtained were processed by means of the volume rendering technique at an advanced workstation (Voxtol 3.0.0; GE Systems, advanced workstation, volume analysis). The cochlea and three semicircular canals were morphologically evaluated. RESULTS: Volume-rendered images of 25 inner ears of 13 patients demonstrated cochlear anomalies in the form of incomplete partition (n=18), hypoplasia (n=2), and severe hypoplasia (n=5). For the superior semicircular canal, findings were normal in 15 ears, though common crus aplasia (n=6), hypoplasia (n=4), aplasia (n=3), and a short and broad shape (n=2) were also observed. The posterior semicircular canal of 13 ears was normal, but common crus aplasia (n=6), a short and broad shape (n=5), aplasia (n=4), hypoplasia (n=3) were also identified. Twelve lateral semicircular canals, were normal, but other images depicted a short and broad shape (n=7), a dilated crus (n=5), a broad shape (n=4), and aplasia (n=2). In 14 patients the anomalies were bilateral, and in seven, the same anomalies affected both ears. CONCLUSION: Three-dimensional volume rendering images of the inner ear depicted various morphological abnormalities of the cochlea and semicircular canals. At that locations, anomalies were more complicated and varied than in the cochlea. Three-dimensional volume rendering imaging using the MR CISS technique provides anatomical information regarding the membranous labyrinth, and we consider this useful in the evaluation of congenital inner ear malformations.
Cochlea ; Ear ; Ear, Inner* ; Humans ; Semicircular Canals

Benign paroxysmal positional vertigo (BPPV) is characterized by brief recurrent episodes of vertigo triggered by changes in head position. BPPV is the most common etiology of recurrent vertigo and is caused by abnormal stimulation of the cupula by free-floating otoliths (canalolithiasis) or otoliths that have adhered to the cupula (cupulolithiasis) within any of the three semicircular canals. Typical symptoms and signs of BPPV are evoked when the head is positioned so that the plane of the affected semicircular canal is spatially vertical and thus aligned with gravity. Paroxysm of vertigo and nystagmus develops after a brief latency during the Dix-Hallpike maneuver in posterior-canal BPPV, and during the supine roll test in horizontal-canal BPPV. Positioning the head in the opposite direction usually reverses the direction of the nystagmus. The duration, frequency, and symptom intensity of BPPV vary depending on the involved canals and the location of otolithic debris. Spontaneous recovery may be expected even with conservative treatments. However, canalithrepositioning maneuvers usually provide an immediate resolution of symptoms by clearing the canaliths from the semicircular canal into the vestibule.
Gravitation ; Head ; Otolithic Membrane ; Semicircular Canals ; Vertigo