What is otoscalorosis?

Definition, Etiology, Epidemiology

Otosclerosis is the most common cause of stapes fixation. It is primarily a disease of the bone that encases the cochlea and labyrinth.The disease mostly starts in the anterior part of the oval window, the so-called fissula ante fenestram and extends to the annular ligament and stapes, where it causes bony ankylosis of the stapes, which results in increased stiffness of the ossicular chain and conductive hearing loss.The inner ear structures are often uninvolved, but sometimes, advanced otosclerosis of the labyrinthine capsule occurswithout conductive hearing loss. In those cases, progressive, degenerative changes in the inner ear occur, with atrophy of the spiral ligament, and they cause an additional sensorineural hearing loss.The typical natural history of otosclerosis is characterized by a slow progressive conductive hearing loss.
                                    When the cochlear otic capsule is also involved, a concomitant sensorineural hearing loss develops.  The disorder is usually bilateral, but the progression rate is different for the two ears, and otosclerosis may present as a unilateral conductive or mixed hearing loss.Females appear to be affected at twice the rate of males. During pregnancy, otosclerosis frequently becomes apparent or aggravates, which suggests that female hormones play an important role in the pathophysiology.

Diagnostic Management 

The diagnosis of otosclerotic hearing loss is usually unproblematic. A positive family history is found in about 50% to 60% of the cases. Clinical bilateral affection is common (85%-90%). Tinnitus, which is mostly low-pitched (~ 75%), is also a common symptom of otosclerosis.Tinnitus is most common in those patients with severe hearing loss. It is frequently encountered in the older age group and in those with an early age of onset and cochlear involvement.
Three types have been described: 
1. Periods of unsteadiness and dysequilibrium (20 min – 6 h) with normal caloric response, and without nystagmus.
2. Periods of postural instability. 
3. Menièriform attacks with increased tinnitus, fluctuating hearing loss, caloric tests are normal or show hyporeflexia. 

Otoscopy

Otoscopy reveals a normal eardrum with an air filled middle ear. The sign of Swartze, which refers to a reddish blush on the promontory, is a rare finding and reflects abnormal vascular shunts between otosclerotic foci and the vessels of the promontory. 

Tuning Fork Test result in Otosclerosis

Tuning fork tests are very helpful for evaluating a patient with otosclerosis. During Weber’s test, sound lateralizes to the ear with the greatest degree of conductive loss and during Rinne’s test, sound will be heard louder when delivered on the mastoid tip compared to delivering via the ear canal.

What is the main reason behind paracusis Willis in conductive deafness or in otosclerosis patient?

Many patients (20%-78%) with otosclerosis have increased understanding of speech during a cocktail party, the so called paracusis of Willis. This phenomenon occurs because the conductive hearing loss attenuates the background noise and renders the dynamic range of the ear at the level of the speaker’s voice, thus effectively increasing the signal to noise ratio.

                                                                                            paracusis Willis Ability to hear a conversation batter in a noisy environment then in a quiet one.