Fall 2016, Volume 7, Issue 6
Welcome back to EBSCO Health's free evidence-based nursing newsletter. We will periodically send news on the latest evidence in nursing. Please share this with your colleagues, students, practitioners and others who would benefit from this information.
Susan is a 15-year-old girl being treated in the hospital for pneumonia. Susan has a history of sickle cell disease, so the nurse would like to know more about acute chest syndrome as a complication of sickle cell disease associated with infection. He consults Nursing Reference Center Plus, keying in the words "Acute Chest Syndrome." He retrieves the quick lesson "Acute Chest Syndrome."
The nurse reads about acute chest syndrome, including risk factors, signs and symptoms, potential complications, laboratory tests, treatment goals and interventions. Based on the information in the quick lesson, the nurse carefully monitors Susan for signs and symptoms of acute chest syndrome and educates her family about the signs and symptoms of acute chest syndrome.
Note: The above-referenced quick lesson is freely accessible to all readers of the EBSCO Health Nursing Newsletter.
Superior semicircular canal dehiscence syndrome (also referred to as superior canal dehiscence syndrome [SCDS]) is rare a disorder of the inner ear (i.e., the cochleovestibular system) manifesting in various vestibular and auditory dysfunctions. Complications associated with SCDS are hearing loss and balance disturbances. It is believed that SCDS is a result of bony dehiscence of the overlying area of the superior semicircular canal that is elicited by varying degrees of pressure or sound-induced vestibular or auditory symptoms.
The inner ear has two openings, the oval and round windows. Sound is perceived through the oval window when it enters the cochleovestibular system and travels by hydroacoustic waves in the perilymph. The round window has several roles; it stimulates the movement of the cochlear hair cells from the perilymph-filled scala tympani to release sound, and contributes to the secretion and absorption of substances in the inner ear. The oval and round windows regulate hearing and balance in conjunction with one another; it is thought that a dehiscence in the superior semicircular canal operates as a mobile third window. In response to sound and/or pressure, a resulting third window conduction effect is derived from the endolymph of the labyrinthine system and activates the vestibular system. The endolymph movement repels the superior canal cupula, located in the semicircular canals, away from the utricle and increases stimulation of the afferent neurons of the ampulla of the superior canal. Increased sensitivity to negative pressure changes at the oval and round windows can contribute to changes in the cochleovestibular system.
Diagnosis of SCDS requires conducting a thorough patient history and physical examination. Diagnostic testing includes audiometric evaluation and Rinne testing with a vibrating tuning fork to compare bone conduction (BC) with air conduction (AC). Vestibular testing (VT) with vestibular evoked myogenic potential (VEMP) is a valuable diagnostic tool in individuals with balance disturbances. Confirmation of a bony dehiscence of the overlying superior semicircular canal can be viewed on a high resolution CT scan of the temporal bones of the affected side. There are no specific laboratory tests for the diagnosis of SCDS.
Treatment for SCDS depends on the severity of symptoms. Observation, vestibular rehabilitation therapy (VRT), and/or administration of vestibular suppressants (e.g., meclizine, dimenhyDRINATE) can result in improvement of minor symptoms. Patients with severe symptoms might benefit from surgery. Surgical treatment options include middle fossa craniotomy with closure of the superior canal dehiscence, transmastoid superior canal occlusion, transcanal occlusion of the round window niche, and complete round window niche occlusion. Transcanal approaches are less invasive than the transmastoid and craniotomy procedures. Prognosis is generally good, but depends on the treatment employed. Complications from surgery can cause incomplete resolution of hearing loss or balance disturbances and, in some patients, symptoms increase in severity after surgery.
Please log in to your Nursing Reference Center™ or Nursing Reference Center Plus subscription to read the quick lesson on "Superior Semicircular Canal Dehiscence Syndrome."
Recently, the evidence-based care sheet "Coronary Artery Disease: Novel (Nontraditional) Cardiac Risk Factors" was revised following review under the Systematic Literature Surveillance Program. Among new information of value to nursing practice was a research study regarding nontraditional cardiac risk factors.
Researchers in an 8-year study of 3,217 adults reported that coronary artery calcium scores improved risk discrimination and reclassified 85% of intermediate-risk participants to either low- or high-risk categories.
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