Decision #69/14 - Type: Workers Compensation
Preamble
The worker is appealing the decision made by the Workers Compensation Board ("WCB") that his claim for noise induced hearing loss ("NIHL") was not acceptable. A hearing was held on April 15, 2014 to consider the matter.Issue
Whether or not the claim is acceptable.Decision
That the claim is not acceptable.Decision: Unanimous
Background
In 2006, the worker filed a claim with the WCB for hearing loss which he attributed to noise generated by lawn mowers during his employment as a labourer between the period 1982 and 1995.
On February 1, 2007, the worker advised a WCB case manager that he had left ear surgery in 2006 related to otosclerosis. The worker felt that 30% of his hearing loss was due to this disease and the other 70% was due to noise exposure at work.
On February 19, 2007, the employer submitted a Sound Survey Report Form dated July 12, 1999 which outlined the type of machinery that was used by the worker along with the decibel readings for each.
On May 23, 2007, the WCB's ear, nose and throat ("ENT") specialist reviewed the worker's claim file and stated:
Worker has otosclerosis and had underwent left stapedectomy in 2006 without much improvement in his hearing. The audiograms of 2005 and 2006 do not support NIHL..
The maximum loss in bone conduction thresholds is at 2000 Hz, which represents Carhart Notch, seen in otosclerosis.
In a letter dated May 31, 2007, the treating otolaryngologist stated:
[The worker] was taken to the operating room for a left stapedectomy on August 2, 2006. This is mostly in keeping with an otosclerosis type of picture. His hearing did not improve very much post-stapedectomy. He may ultimately require a hearing aid on that side or further intervention depending upon his issue. The question is whether there was a noise overlay to the otosclerosis. This would be difficult to tell at this point but is certainly plausible.
On July 23, 2007, the WCB's ENT consultant reviewed the May 31, 2007 report and stated that the audiograms did not support the diagnosis of NIHL but indicated otosclerosis.
By letter dated July 23, 2007, the WCB advised the worker that his claim for hearing loss was not acceptable based on the WCB medical opinion dated May 23, 2007. The letter also stated:
The Workers Compensation Board has established that for a claim for noise induced hearing loss to be compensable, the worker must have had exposure to noxious noise for a minimum period of two years, based generally upon an average of 85 decibels for 8 hours of exposure on a daily basis, with a doubling factor of 3 decibels (i.e., for every increase in exposure of 3 decibels the allowable time of exposure is reduced by one half).
We have not been able to confirm your hearing loss was a result of noise exposure at work, therefore, the claim is not acceptable.
On September 7, 2007, the worker wrote the WCB stating that the 2006 stapedectomy to his left ear had corrected the otosclerosis but he still had moderate mixed hearing loss in his left ear and mild mixed loss in his right ear. The worker's position was that his degree of hearing loss was attributable to his exposure to prolonged loud workplace noises and he referenced the audiogram results of September 4, 2007.
On September 12, 2007, the WCB case manager advised the worker that no change could be made to the decision on his hearing loss claim. The case manager indicated that the information from the treating otolaryngologist dated May 31, 2007 had been reviewed by the WCB ENT specialist along with the other medical information and that the audiograms did not support a diagnosis of NIHL. The worker's file was then referred to Review Office for consideration of the worker's appeal.
On October 29, 2007, Review Office confirmed that the worker's claim was not acceptable. Review Office reviewed the file evidence and agreed with the position taken by the case manager in her July 23, 2007 decision.
On November 2, 2007, the worker advised Review Office that in June 2007 he had further surgery and that his treating otolaryngologist felt there was a NIHL component to his hearing problems. Based on this information, Review Office wrote the treating otolaryngologist for a copy of the operative report and asked him to comment on whether or not he felt that NIHL played a role in the worker's hearing situation following the second surgery.
In a letter to Review Office dated November 8, 2007, the treating otolaryngologist noted that the worker was taken back to the operating room for re-exploration as his prosthesis was not ideally placed. He also stated:
The role of the second surgery does not really clarify any of the issues surrounding his noise components of his sensorineural hearing loss, although I would suspect that there is some component at least in his right ear of noise exposure.
At the request of Review Office, the WCB's ENT specialist reviewed the information from the treating otolaryngologist and stated:
The configuration of the audiogram in the right ear does not support NIHL. In NIHL the greater loss would be around 4000 Hz. In worker's case 4000 Hz. is his best frequency in the right ear. In conclusion, there is no new evidence to support NIHL.
Based on the WCB ENT specialist's opinion, Review Office advised the worker on December 12, 2007 that the new evidence on file did not provide grounds to alter its previous decision.
On October 2, 2008, the treating otolaryngologist wrote Review Office and stated:
As per my previous correspondence in May 2008, [the worker] still suffers from a neural component of hearing loss, at least in his left ear. Certainly, the pattern in both ears, particularly in the 4,000 and 2,000 range is in keeping with a noise exposure type of loss. I would support his claim that his hearing loss with the right being more definitive than the left, is due to noise exposure.
The WCB's ENT specialist reviewed the otolaryngologist's October 2, 2008 report and stated:
File and audiograms reviewed. Worker has mixed hearing loss bilaterally and was diagnosed with otosclerosis. If noise exposure played a role in his hearing loss, I would expect bone conduction thresholds to be worse between 3000 - 6000 Hz. The worker's
audiogram shows equal loss in bone conduction thresholds across all frequencies, with the maximum loss at 2000 Hz., indicative of Carhart Notch seen in otosclerosis. Also, conductive hearing loss tends to protect the inner ear from noise exposure. The audiograms suggest cochlear otosclerosis causing the sensorineural component to the hearing loss. In my opinion, noise exposure did not play a role in the worker's hearing loss.
On October 23, 2008, Review Office referred to the WCB medical opinion noted above and confirmed to the worker that the evidence on file did not alter its two prior decisions. On January 20, 2014, the worker appealed Review Office's decision to the Appeal Commission and a hearing was arranged.
Reasons
Applicable Legislation
The Appeal Commission and its panels are bound by The Workers Compensation Act (the “Act”), regulations and policies of the Board of Directors. Under subsection 4(2) of the Act, a worker who is injured in an accident (as defined under the Act) is entitled to wage loss benefits for the loss of earning capacity resulting from the accident.
WCB Policy 44.20.50.20.01, Hearing Loss (the “Policy”) sets out guidelines related to claims for hearing loss arising from long-term exposure to occupational noise. The Policy is applicable to claims arising from accidents on or after April 1, 2000 with a date of notification prior to October 1, 2013. As the worker's hearing loss was first identified by audiogram on November 21, 2006, this is his date of accident/claim establishment and the Policy is applicable.
The Policy states in part that:
2. Claims for long-term exposure to noxious noise may be considered and paid on the basis of a claimant’s exposure with employers who are or had been registered in Manitoba.
3. Not all hearing loss is caused by exposure to noise at work. The WCB will be satisfied that hearing loss occurred at work when a worker is exposed to noxious noise at work for a minimum of two years, based generally upon an average of 85 decibels for 8 hours of exposure on a daily basis. For every increase in noise level of 3 decibels, the required exposure time will be reduced by half.
Worker’s Position
The worker was self-represented at the hearing. The worker did not deny that he had otosclerosis and that this contributed to his hearing loss. It was submitted, however, that the worker's doctors had told him that he had "mixed hearing loss" and his understanding of mixed hearing loss was that it meant that noise contributed, at least partially, to his hearing loss. The worker's history with the employer was that he worked for approximately 12 years in its outdoor maintenance department. In that position, he performed duties such as cutting grass, using weed eaters, lawnmowers (both push and riding), and chainsaws to cut and trim trees. When the worker worked for this employer, he was younger and at the time, did not take care to use hearing protection nor was it enforced. It was submitted that the information on file demonstrated that the equipment the worker was using during that time period ranged from 87.3 decibels up to 107 decibels. This fell within the guidelines set out in WCB Policy.
The worker felt that his claim was rejected because there was controversy over whether his hearing loss was caused by otosclerosis or whether it was noise induced. The WCB ENT consultant maintained that the hearing loss was exclusively otosclerosis but the worker's own specialist had told the worker that he had a noise induced hearing loss. The worker's audiologist was also of the opinion that noise exposure while working for the employer partially contributed to the worker's hearing loss.
Overall, the worker submitted that he had a mixed hearing loss and part of that was a noise induced hearing loss which was sustained during the 12 years when he worked for the employer. The equipment he used generated noise above the required 85 decibels and partially contributed to the hearing problems he experienced at the present time.
Employer's Position
A compensation coordinator appeared on behalf the employer at the hearing. The employer's position was that the preponderance of evidence supported the decision made by the WCB. It was submitted that the panel should rely on a qualified expert to comment on the audiometric testing and the opinion provided by the worker's audiologist. It was noted, however, that although the audiologist concluded that the worker's employment contributed, at least in part, to the worker's hearing loss, there was no indication that the audiologist was cognizant with the equipment used or the decibel levels involved. Further, it was noted that the audiologist referenced a "sudden hearing loss in his right ear on December 22, 2013." The panel was reminded that the worker left the employ of the employer in 1995. Based on the detailed information provided by the WCB ENT consultant, it was submitted that his evidence should be preferred over that of the audiologist.
With respect to the worker's own treating specialist, it was submitted that his opinion was made from a presumptive rather than definitive standpoint. It was noted that in his report of May 31, 2007, the specialist stated: "The question is whether there was a noise overlay to the otosclerosis. This would be difficult to tell at this point but is certainly plausible."
The panel was called upon to deny the appeal.
Analysis
The worker in this case claims that at least part of his hearing loss documented in an audiogram conducted in September 2005 relates to his employment during the years 1982 to 1995. In order for the worker’s appeal to be successful, the panel must find that during the course of his employment with the accident employer, the worker sustained NIHL due to exposure to high levels of noxious noise as set out in the Policy. The issue concerns causation, and whether his hearing loss was due to workplace noise exposure, or whether it was due to his non-work related otosclerosis. On a balance of probabilities, we find that the worker's hearing loss was due to the non-work related cause, and therefore his claim is not acceptable.
It may be useful at the outset to clarify some of the terms being used in the reports on file. Conductive hearing loss occurs when sound is not conducted efficiently through the outer ear canal to the eardrum and the tiny bones (ossicles) of the middle ear. This type of hearing loss can often be corrected medically or surgically. The panel understands that the worker's otosclerosis could cause conductive hearing loss.
Sensorineural hearing loss occurs when there is damage to the inner ear (cochlea) or to the nerve pathways from the inner ear to the brain. Exposure to noxious noise is a possible cause of sensorineural hearing loss, but is not the only cause. Sensorineural hearing loss can also be caused by illness, ingestion of toxic drugs, genetic/hereditary factors, aging, head trauma or malformation of the inner ear. The panel understands that otosclerosis could also cause sensorineural hearing loss.
The term "mixed hearing loss" refers to when a conductive hearing loss occurs in combination with a sensorineural hearing loss. In other words, there may be damage to both the outer/middle ear and also in the inner ear or auditory nerve. The panel notes that the term "mixed hearing loss" refers to the areas where the ear's anatomy is not properly functioning, but does not necessarily refer to the reason for the impaired hearing.
In application to this case, the worker submits that since his specialist states he has mixed hearing loss, this must mean that he has some component of NIHL. For the reasons set out above, the panel finds that this is not necessarily the case.
In the panel's opinion, this case must be determined based on the results of the audiogram conducted on September 21, 2005. As a starting point, before there can be a compensable claim for hearing loss caused by prolonged workplace exposure to noise, there must be evidence of NIHL. It is the panel's understanding that NIHL is characterized by an audiometric notch with greater loss at frequencies 3000-6000 Hz, and loss usually greatest at 4000 Hz with recovery at 6000 Hz and 8000 Hz. The WCB ENT consultant reviewed the worker's 2005 and 2006 audiograms and noted that they demonstrated maximum loss in bone conduction thresholds at 2000 Hz, which represented Carhart Notch, seen in otosclerosis. In his opinion, the audiograms did not support the diagnosis of NIHL. In his memo of October 22, 2008, the WCB ENT consultant gave a technical and specific explanation of why he came to the opinion that the audiograms demonstrated that noise exposure did not play a role in the worker's hearing loss. The WCB ENT agreed that the worker had mixed hearing loss and in his opinion, the audiograms suggested cochlear otosclerosis caused the sensorineural component to the hearing loss and stapedial fixation caused the conductive component to the hearing loss.
With respect to the worker's treating specialist, although he did opine in his October 2, 2008 letter that the pattern in both the worker's ears, particularly in the 4000 and 2000 range is in keeping with a noise exposure type of loss, he did not provide an explanation as to why he reached this conclusion. Also to be kept in mind is the specialist's earlier statement in his letter of May 31, 2007 that it would be difficult to tell whether or not there was a noise overlay to the otosclerosis.
Similarly, the audiologist's report of April 3, 2014 opined that exposure to noise partially contributed to the worker's hearing loss, but no explanation was provided at to why the audiologist reached this conclusion.
In view of the foregoing, the panel places greater weight on the opinion of the WCB ENT specialist.
Overall, on a balance of probabilities, the panel finds that the audiogram results do not support a finding of NIHL and we therefore find that the worker does not have an acceptable claim for hearing loss caused by prolonged exposure to workplace noise.
The worker's appeal is dismissed.
Panel Members
L. Choy, Presiding OfficerA. Finkel, Commissioner
P. Walker, Commissioner
Recording Secretary, B. Kosc
L. Choy - Presiding Officer
Signed at Winnipeg this 9th day of June, 2014