Helen knew something was wrong as soon as she woke up. The world was suddenly mono instead of stereo: she couldn't hear out of her right ear.
She hadn't had a cold or been unwell, so at first she brushed it off as nothing. But overnight, ordinary events — conversations with friends, the open plan office at work — became distressing.
"It was frightening. I went out with my husband … we went out for dinner. It was just dreadful. The sound was bouncing off the walls, making me feel ill, making me dizzy," she said.
And when it hadn't gone away by the next morning, Helen's concerns grew.
"I thought I'd just pop along to the GP and see if they could say what it is or tell me I've got nothing to worry about," she said.
Unfortunately, she did have something to worry about...
The GP urged Helen to get to an emergency room as soon as possible. Though Helen didn't know it, she was at risk of permanently losing hearing in that ear unless doctors acted fast.
"Sudden sensorineural hearing loss" (SSNHL), otherwise known as sudden deafness, is a loss of hearing over hours or days with no obvious cause.
Helen is a typical case — an otherwise healthy person who goes to sleep and wakes up without hearing in one (or rarely, both) ears.
And it's often missed by doctors, according to ear, nose and throat surgeon Peter Friedland.
"Unfortunately, it's often brushed off and the patient isn't taken seriously or they're dismissed," Professor Friedland said. "It can be related to other causes that are more common. Hence it's not investigated as a possibility of causing this sudden loss of hearing, which can be permanent."
"The loss of hearing is devastating because we need both ears to hear with. For direction, binaural hearing, safety crossing a road, conversations with background noise," he said.
After heading to emergency, the registrar at the hospital couldn't find anything wrong with Helen's hearing, she says. "He did some basic tests with me … and said, 'Nah, I can't see there's a problem'," Helen said.
"He vaguely mentioned steroids, and to go and see an audiologist at some stage. And that was it."
But the clock was ticking for Helen.
The main treatment for SSNHL is steroids, and for the best chance of recovery they have to be given in the first 72 hours of hearing loss. While some people will spontaneously get better without treatment, many don't.
"They can cause mood disorders, a bit of anxiety, some dizziness, inflammation of the stomach, insomnia," Professor Friedland said.
After a visit to an audiologist who confirmed her hearing loss, Helen went back to see another GP. It was now three days since she'd first noticed the change.
"He said, 'you should be on steroids'. So I started them within an hour," she said.
For those who don't respond to the steroids, hyperbaric oxygen therapy is another option.
It involves being in a special chamber where you breathe in 100 per cent oxygen. By contrast, the air we breathe in every day is about 20 per cent oxygen.
The rationale for this treatment is that injured tissue may need more oxygen than usual to promote healing.
Hyperbaric oxygen therapy increases the amount of oxygen your blood can carry, which encourages healing and the fighting of infection.
"If we believe there's been decreased blood supply to the cochlea, then by giving hyperbaric oxygen we're increasing oxygen perfusion to the cochlea and improving the healing and repair of the inner hair cells and the membranes within the cochlea," Professor Friedland said.
"But hyperbaric oxygen therapy is expensive — around $500 an hour [not at SoCal Hyperbarics] — with up to 20 hours of therapy recommended for the treatment of SSNHL."
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