Misplaced Pages

#557442

22-433: SCDS may refer to: Superior canal dehiscence syndrome , a medical condition of the inner ear leading to hearing and balance disorders Sequential compression devices Sacramento Country Day School Savannah Country Day School Seattle Country Day School SimCity DS - a simulation/city building computer game Sonoma Country Day School Topics referred to by

44-496: A VsEPL response. In contrast to VsEPA, researchers have standardized the VsEPL stimuli but many variants of this standard are being used in research laboratories today. The stimulus needs to be a transient, rapidly changing pulse (i.e. linear jerk stimulus). A rectangular jerk step/pulse is generated by an electromechanical shaker. The main downfall of the VsEPL response is the presence of electrical artifacts due to movement and touching of

66-474: A consequent high failure rate; recently, soft tissue grafts have been substituted. Occasionally this disorder has been referred to as Minor's syndrome, after its discoverer, Lloyd B. Minor . However, that eponym has also been given to an unrelated condition, the paralysis and anaesthesia following a spinal injury, which is named after the Russian neurologist, Lazar Minor (1855–1942). In the latter case this term

88-428: A loose relationship to VEMPs. This kinematic stimuli needs to be well characterized, precisely controlled, consistent in amplitude, and consistent in kinematic makeup. An electromechanical shaker is a stimuli generator that is widely available. This shaker provides a transient stimuli, can generate angular or linear acceleration, and can couple to the skull directly (with skull screws) or via a stimulus platform. The VsEP

110-476: A patient with a short latency response to loud clicks studied using a modified recording site (the sternocleidomastoid muscles: SCM) and which was abolished by selective vestibular nerve section. Colebatch et al. (1994) described the basic properties of the response. These were: the response occurred ipsilateral to the ear stimulated, the click threshold was high, the response did not depend upon hearing ( cochlear function) per se, it scaled in direct proportion to

132-448: A short latency response in posterior neck muscles in response to loud clicks that appeared to be mediated by activation of the vestibular apparatus. These authors made the additional important observations that the response was generated from EMG (muscle) activity and that it scaled with the level of tonic activation. Subsequent work led to the suggestion that the saccule was the end organ excited. In 1992 Colebatch and Halmagyi reported

154-600: Is a sensory organ with the primary purpose to aid in hearing. The otolith organs (utricle and saccule) are sensors for detecting linear acceleration in their respective planes (utrical=horizontal plane (forward/backward; up/down); saccule=sagital plane (up/down)), and the three semicircular canals (anterior/superior, posterior, and horizontal) detect head rotation or angular acceleration in their respective planes of orientation (anterior/superior=pitch (nodding head), posterior=roll (moving head from one shoulder to other), and horizontal=yaw (shaking head left to right). Located within

176-458: Is commonly divided into two sections: angular vestibular evoked potentials (VsEPA) and linear vestibular evoked potentials (VsEPL). VsEPA stimuli needs to be a brief or transient, high amplitude, angular acceleration pulse. Currently, the most effective stimuli for the best results have not yet been identified or agreed upon by researchers. The major downfall of the VsEPA response is that it also elicits

198-409: Is different from Wikidata All article disambiguation pages All disambiguation pages Superior canal dehiscence syndrome The superior semicircular canal dehiscence syndrome ( SSCDS ) is a set of hearing and balance symptoms that a rare disease/disorder of the inner ear 's superior semicircular canal/duct induces. The symptoms are caused by a thinning or complete absence of

220-420: Is now nearly obsolete. VEMP The vestibular evoked myogenic potential ( VEMP or VsEP ) is a neurophysiological assessment technique used to determine the function of the otolithic organs ( utricle and saccule ) of the inner ear . It complements the information provided by caloric testing and other forms of inner ear ( vestibular apparatus ) testing. There are two different types of VEMPs. One

242-462: Is the oVEMP and another is the cVEMP. The oVEMP measures integrity of the utricule and superior vestibular nerve and the cVemp measures the saccule and the inferior vestibular nerve. The vestibular system helps a person maintain: balance , visual fixation , posture , and lower muscular control. There are six receptor organs located in the inner ear: cochlea, utricle, saccule, and the lateral, anterior, and posterior semicircular canals. The cochlea

SECTION 10

#1732944376558

264-410: The vestibular evoked myogenic potential or VEMP test, videonystagmography ( VNG ), electrocochleography (ECOG) and the rotational chair test. An accurate diagnosis is of great significance as unnecessary exploratory middle ear surgery may thus be avoided. Several of the symptoms typical to SCDS (e.g. vertigo and Tullio ) may also be present singly or as part of Ménière's disease, sometimes causing

286-592: The SCDS include: According to current research, in approximately 2.5% of the general population the bones of the head develop to only 60–70% of their normal thickness in the months following birth. This genetic predisposition may explain why the section of temporal bone separating the superior semicircular canal from the cranial cavity , normally 0.8 mm thick, shows a thickness of only 0.5 mm, making it more fragile and susceptible to damage through physical head trauma or from slow erosion. An explanation for this erosion of

308-450: The bone has not yet been found. The presence of dehiscence can be detected by a high definition (0.6 mm or less) coronal CT scan of the temporal bone , currently the most reliable way to distinguish between superior canal dehiscence syndrome (SCDS) and other conditions of the inner ear involving similar symptoms such as Ménière's disease , perilymphatic fistula and cochlea-facial nerve dehiscence . Other diagnostic tools include

330-438: The gap in the temporal bone can be repaired by surgical resurfacing of the affected bone or plugging of the superior semicircular canal. These techniques are performed by accessing the site of the dehiscence either via a middle fossa craniotomy or via a canal drilled through the transmastoid bone behind the affected ear. Bone cement has been the material most often used, in spite of its tendency to slippage and resorption, and

352-483: The level of tonic neck contraction, the response was small (although large compared to many evoked potentials) and required averaging, and only the initial positive-negative response (p13-n23 by latency) was actually vestibular-dependent. It was subsequently shown to be generated by a brief period of inhibition of motor unit discharge. VsEP assesses the non-auditory portions of the labyrinth and requires kinematic stimuli (i.e. motion) instead of sound stimuli and bear only

374-480: The membranous labyrinthine walls of the vestibular system are approximately 67,000 hair cells in total. This includes ~7,000 hair cells from each of the semicircular canals located within the crista ampullaris, ~30,000 hair cells from the utricle, and ~16,000 hair cells from the saccule. Each hair cell has about 70 stereocilia (short rod-like hair cells) and one kinocilium (long hair cell). Bickford et al. (1964) and subsequently Townsend and Cody, provided evidence for

396-467: The one illness to be confused with the other. There are reported cases of patients being affected by both Ménière's disease and SCDS concurrently. As SCDS is a very rare and still a relatively unknown condition, obtaining an accurate diagnosis of this distressing (and even disabling) disease may take some time as many health care professionals are not yet aware of its existence and frequently dismiss symptoms as being mental health-related. Once diagnosed,

418-541: The part of the temporal bone overlying the superior semicircular canal of the vestibular system . There is evidence that this rare defect, or susceptibility, is congenital. There are also numerous cases of symptoms arising after physical trauma to the head. It was first described in 1998 by Lloyd B. Minor of Johns Hopkins University in Baltimore . The superior canal dehiscence can affect both hearing and balance to different extents in different people. Symptoms of

440-404: The same term [REDACTED] This disambiguation page lists articles associated with the title SCDS . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=SCDS&oldid=897236010 " Category : Disambiguation pages Hidden categories: Short description

462-486: The vestibular apparatus have been developed, including taps to the head, bone vibration and short duration electrical stimulation. It is likely that both air-conducted and bone-conducted stimuli primarily excite irregularly discharging otolith afferents. The two otolith receptors appear to have differing resonances that may also explain their responses. In addition to the response in the SCM, similar reflexes can be shown for

SECTION 20

#1732944376558

484-589: The wires/electrodes during testing. An early application was in the diagnosis of superior canal dehiscence a condition in which there can be clinical symptoms and signs of vestibular activation by loud sounds. Such cases have a pathologically lowered threshold for the sound-evoked VEMP. The test is also of use in demonstrating successful treatment. It has diagnostic applications in Ménière's disease , vestibular neuritis , otosclerosis as well as central disorders such as multiple sclerosis . Other methods of activating

#557442