Overview
Progressive hearing loss will affect 95% of Superficial Siderosis patients and is often one of the first symptoms of Superficial siderosis. The eighth cranial nerve is a sensory nerve with two main components: the vestibular nerve, responsible for balance, and the cochlear nerve, responsible for hearing. As floating free-iron is trapped by the ferritin protein, it settles as hemosiderin, attaching to the eighth cranial nerve. Progressive loss of neural function slowly results in bilateral-asymmetric sloping sensorineural hearing loss.
Audiologists sometimes misidentify Superficial Siderosis related sensorineural hearing loss as early-stage presbycusis. Professional audiology journals are now publishing articles regarding the importance of identifying at-risk patients by matching their present hearing loss symptoms with past trauma or surgical events from their medical history to help with early diagnosis.
Early Signs
- Muffled hearing
- Difficulty understanding speech
- Gradual loss of hearing
- Feeling of fullness or plugged in the ear
- Ringing in the ear (TinnitusOverview Tinnitus has been described as a soft sign of the ... More)
- Dizziness
The damage to specialized, impulse-conducting cells (neurons) resulting in neuronal loss to the eighth cranial nerve and possible vascular structure compression from gliosis is viewed as permanent.
Bilateral-asymmetric describes while both sides of your hearing will be affected, it will not be an identical loss. Sloping describes how high-frequency hearing will diminish first with lower frequency loss in the later stages as the disorder progresses.
Plan of Care
- Annual audiogram testing is recommended to track the progression
- Evaluation and fitting of a specialized hearing aid(s) to enhance word recognition
- Assistive speech-to-text devices
- Evaluation for surgical options
Some patients have opted to undergo Cochlear Implants with excellent results. Determining, pre-procedure, if the patient has intact and functioning brainstem auditory conduction has proven a good predictor of cochlear implant success.
“it is especially sensitive to damage from superficial siderosis caused by the breakdown of slow or repeated episodes of subarachnoid hemorrhage into hemosiderin. It is postulated that the sensitivity of cranial nerve VIII to subpial hemosiderin deposition is due to its long cisternal segment, which exposes it to a high concentration of iron, in combination with the fact that the transition from central to peripheral myelin occurs near the IAC in cranial nerve VIII but relatively close to the brainstem in cranial nerves III–XII. The central myelin and the microglia that produce it are especially sensitive to siderosis. The high iron concentration lining the brain and cranial nerves will cause local magnetic inhomogeneity and is most easily visualized on susceptibility-weighted or gradient-echo T2*-weighted images. “¹