Superior semicircular canal dehiscence syndrome  is a set of hearing and balance symptoms, related to a rare medical condition of the inner ear, known as superior canal dehiscence. The symptoms are caused by a thinning or complete absence of 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. Symptoms
Superior canal dehiscence (SCD) can affect both hearing and balance to different extents in different people.Symptoms of SCDS include:

Autophony – persons own speech or other self-generated noises (e.g. heartbeat, eye movements, creaking joints, chewing) are heard unusually loudly in the affected ear
Dizziness/ vertigo/ chronic disequilibrium caused by the dysfunction of the superior semicircular canal
Tullio phenomenon – sound-induced vertigo, disequilibrium or dizziness, nystagmus and oscillopsia
Pulse-synchronous oscillopsia
Hyperacusis – the over-sensitivity to sound
Low-frequency conductive hearing loss
A feeling of fullness in the affected ear
Pulsatile tinnitus
Brain fog
Fatigue
Headache/migraine
Tinnitus – high pitched ringing in the ear

Symptoms in detail
SCDS-related autophony differs greatly in quality and range from the more common form which results from an open, or patulous Eustachian tube through which sufferers of this disorder hear the sound of their own voice and breathing. In contrast, patients with SCDS-related autophony report hearing their own voice as a disturbingly loud and distorted "kazoo-like" sound deep inside the head as if relayed through "a cracked loudspeaker."
Osteoporotic bone marrow defect is a condition which may be found in the body of the mandible. It is usually painless and found during routine radiographs. It appears as a poorly defined radiolucency (dark area) where there was a previous history of an extraction of a tooth. It may resemble a metastatic disease. It is a localized increase of hematopoietic bone marrow that creates a radiolucent radiographic defect. They occur more commonly in women in the midyears and show a predilection for the molar region of the mandible. They are especially common in extraction sites. Scattered trabeculae may extend short distances into the defect or, in some instances, through it, giving the defect a fairly characteristic appearance. Naturally there are no clinical symptoms. Cause
The cause remains unknown. Diagnosis
Differential diagnosis
This defect may easily be mistaken for a cyst or tumor. Biopsy is required to rule these out. Treatment
No treatment is required. References

Kahn, Michael A. Basic Oral and Maxillofacial Pathology. Volume 1. 2001.