Idiopathic sudden sensorineural hearing loss (ISSHL) is defined according to American Academy of Otolaryngology as a hearing loss of at least 30 decibel over 3 contiguous test frequencies occurring within a 72h period. It affects 5 to 20 people per 100,000 annually and is characterized by sudden-onset, generally unilateral, sensorineural hearing loss. Its cause is idiopathic in most of the patients; however, vascular disorders have been proposed as the final common pathway. Recent studies have reported that the impaired microvascular perfusion occurring during an ischemic event may be related to oxidative stress which may be synergistically responsible for endothelial damage, especially in terminal microvascular systems.

Hydrogen, which serves as a free radical scavenger and can reduce the strong oxidants, is found as a therapeutic gas in cochlea in recent studies. Both antioxidant and anti-inflammatory effects have been seen with hydrogen administration in animal models. Since cisplatinum toxicity and acoustic trauma both involve oxidative stress to the cochlea, hydrogen may prove useful in these conditions. The efficacy and safety of hydrogen inhalation are also proved in clinical studies.

Given the theories mentioned above, the purpose of our study is to use inhaled hydrogen as an adjuvant therapy for treating idiopathic sudden sensorineural hearing loss. The systemic inflammation status and oxidative stress will be monitored. Both subjective and objective efficacy after treatment will be assessed.

Inclusion Criteria:

1. Meet the criteria of definition of sudden sensorineural hearing loss: hearing loss of 30 dB or more over at least three contiguous frequencies, over a period of 72 hours or less.
2. The event attacked within 14 days. -

Exclusion Criteria:

1. pregnancy or other vulnerable groups
2. specific etiologies of sudden sensorineural hearing loss
3. Diabetes mellitus patients -

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