Hereditary connective tissue diseases include autosomal polycystic kidney disease, Ehlers-Danlos syndrome, Marfan syndrome, fibromuscular dysplasia, and osteogenesis imperfecta type 1 although studies have shown that the link between hereditary connective tissue diseases and cervical artery dissection is low, ranging from 0-0.6% in one study and 5-18% in another study. Traumatic
Traumatic cervical artery dissections are dissections that occur after any sort of trauma to the neck, ranging from minor trauma such as nose-blowing or sneezing to severe trauma such as roadside accidents. Most traumatic dissections are secondary to some form of rapid decelerations injuries resulting in hyperextension or hyperflexion with rotational injury of the neck. Pathophysiology
Cervical artery dissections begin initially with a small tear in the innermost layer of the arterial wall, the tunica intima, or rupture of the vasa vasorum with bleeding within the media. As the arterial wall begins to tear, blood begins to enter this newly formed false lumen and the resulting hematoma formation can either narrow (stenosis) or occlude the artery, decreasing or completely blocking blood flow through the artery. A complete occlusion of the artery can result in cerebral ischemia as the brain is depleted of oxygen-rich blood. Because the brain has a pair of carotid and vertebral arteries on each side of the neck, a unilateral occlusion can be asymptomatic, as the bilateral circulation continues perfusing the brain. Thrombus formation is the natural physiologic response to the vascular injury to prevent significant blood loss.
On an audiogram, the "x" represents responses in the left ear at each frequency, while the "o" represents responses in right ear at each frequency. CT scan
Most causes of conductive hearing loss can be identified by examination but if it is important to image the bones of the middle ear or inner ear then a CT scan is required. CT scan is useful in cases of congenital conductive hearing loss, chronic suppurative otitis media or cholesteatoma, ossicular damage or discontinuity, otosclerosis and third window dehiscence. Specific MRI scans can be used to identify cholesteatoma. Pathophysiology
Management
Management falls into three modalities: surgical treatment, pharmaceutical treatment, and supportive, depending on the nature and location of the specific cause. In cases of infection, antibiotics or antifungal medications are an option. Some conditions are amenable to surgical intervention such as middle ear fluid, cholesteatoma, and otosclerosis. If conductive hearing loss is due to head trauma, surgical repair is an option. If absence or deformation of ear structures cannot be corrected, or if the patient declines surgery, hearing aids which amplify sounds are a possible treatment option. Bone conduction hearing aids are useful as these deliver sound directly, through bone, to the cochlea or organ of hearing bypassing the pathology. These can be on a soft or hard headband or can be inserted surgically, a bone anchored hearing aid, of which there are several types. Conventional air conduction hearing aids can also be used. See also
Hearing loss
Sensorineural hearing loss

References


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