The Appeal CommissionThe Workers Compensation Act of Manitoba

Preamble

The worker is appealing the decision made by the Workers Compensation Board ("WCB") that they are not entitled to further benefits in relation to the November 12, 2014 accident. A videoconference hearing was held on September 11, 2025 to consider the worker's appeal.

Issue

Whether or not the worker is entitled to further benefits in relation to the November 12, 2014 accident.

Decision

The worker is not entitled to further benefits in relation to the November 12, 2014 accident.

Background

The worker filed a Worker Incident Report with the WCB on November 18, 2014, reporting that while at work on November 12, 2014, they mixed two cleaning chemicals together which resulted in them having difficulty breathing and fits of coughing, then experiencing a “very bad headache” and suffering a respiratory injury. The worker finished their shift and noted they did not miss time due to the incident. The worker contacted the WCB on the same date and advised they had previously been diagnosed with mild asthma but did not need to carry medication for it.

On December 18, 2014, the WCB spoke with the worker’s supervisor who confirmed the worker had been using new cleaning chemicals that day and had not missed time from work. The employer provided the WCB with the Material Safety Data Sheet for the product used by the worker the following day.

On June 12, 2015, the worker contacted the WCB to advise they had been terminated from their position with the employer. The worker advised the WCB they had been suffering from constant migraine headaches since January 2015, which they believed were caused by the November 12, 2014 workplace incident. They noted they had sought medical treatment since January 2015 and had been referred for an MRI study. The WCB advised the worker their WCB claim had been closed since December 2014 as the worker had not missed time from work and reported no ongoing difficulties.

The next contact from the worker was on May 13, 2016, when they submitted a new Worker Incident Report and enclosed additional information. The worker advised the WCB they had been seen by a neurosurgeon on May 10, 2016, after suffering from constant headaches. The worker advised that the "…violent coughing from the chlorine gas…" they were exposed to in November 2014 caused a brain injury, and that they had been referred to a further specialist for treatment for a diagnosed low pressure cranial fluid leak. The worker noted they had undergone an MRI study of their brain prior to the November 12, 2014 workplace accident in November 2013 which was found to be normal. The worker also attended at the WCB on May 25, 2016 to provide copies of further documents.

The WCB met with the worker on May 27, 2016 to discuss the worker’s claim. The worker confirmed the events of the accident and advised that they attended at a local clinic the morning after and spoke with a nurse who advised that if they were not experiencing excessive coughing, they did not need to go to the hospital. The worker advised they were not coughing very much that day. The worker again noted their headaches that began in January, 2015, their June, 2015 termination from employment, and their July, 2015 MRI study referral. The worker advised that after receiving the results of the MRI study, they were told they had a spinal fluid leak and were referred to their treating neurosurgeon, who then referred the worker to a specialist for further treatment.

The worker's treating neurosurgeon provided the WCB with their chart notes and diagnostic imaging for the period of September 11, 2015 to May 10, 2016 on June 10, 2016. The September 11, 2015 report from the neurosurgeon to the worker's treating family physician noted the worker's reporting of developing "an intractable posterior headache" in January 2015, with a new MRI study indicating signs of intracranial hypotension. The neurosurgeon further noted the worker did not provide an inciting cause of the headaches but mentioned a fall on their back 18 months previously and a period of fits of coughing which they related to the November 12, 2014 workplace accident. The neurosurgeon diagnosed the worker with intracranial hypotension, pending further diagnostic imaging.

After the worker underwent further imaging on February 1, 2016, the neurosurgeon produced a further report to their treating family physician on May 10, 2016 and confirmed the intracranial hypotension diagnosis. On July 29, 2016, the WCB provided the worker with a decision letter advising they were not entitled to further benefits as a causal relationship between their current difficulties and the November 12, 2014 workplace accident could not be established.

On June 26, 2017, the worker submitted a Request for Review to Review Office, advising they had been diagnosed with "secondary acquired Chiari malformation", and provided a fact sheet from the internet regarding that condition. Review Office returned the worker's file to the WCB's Compensation Services for further investigation on June 27, 2017. The WCB requested, and on July 17, 2017 received, chart notes from the worker's treating neurosurgeon.

A September 6, 2016 report to a pain clinic noted the worker received limited head pain relief from a blood patch and requested a further patch procedure to find if the worker achieved longer term relief. A January 24, 2017 report to the worker's treating family physician provided an update indicating testing had not found the potential cerebral spine fluid (CSF) leak that was causing the worker's symptoms, but further investigations were ongoing. The March 27, 2017 report to the treating physician noted a referral to an interventional radiologist for further treatment.

The WCB requested a review of the medical information on the worker's file by a WCB medical advisor, who advised on August 8, 2017, that they were requesting further information from the worker's treating healthcare providers. After being unable to receive any updated information as it was not available, the WCB medical advisor placed their opinion to the worker's file on September 25, 2017. The advisor opined the worker had a temporary reaction to a self-limited irritant on November 12, 2014, which likely resolved within a day, based on the information on the worker's file. The advisor noted that there was no diagnosis of secondary acquired Chiari malformation in the worker’s medical records on file. The advisor opined that the medical information on file did not support a connection between the worker's diagnosis of intracranial hypotension, manifest as an intractable posterior headache in January 2015, with the workplace accident of November 12, 2014. On the same date, the worker was provided with a formal decision letter advising there would be no change to the earlier decision that they were not entitled to further benefits in relation to the November 2014 workplace accident.

The worker again submitted additional medical information to Review Office on February 7, 2023 and requested reconsideration of the WCB's decision that they were not entitled to further benefits. On February 8, 2023, Review Office returned to the worker's file to the WCB's Compensation Services for further adjudication.

The worker's file and the additional medical information, including reports of the treating neurologist dated February 11, 2022, June 13, 2022 and November 24, 2022, were reviewed by a WCB medical advisor on April 13, 2023. The advisor noted the worker's treating neurologist had referred the worker for further diagnostic imaging and found "…evidence of intracranial hypotension due to a probable CSF-venous fistula [an enlargement of the channel that normally drains CSF into a spinal vein] at the right T8-T9 level of the thoracic spine." The advisor further noted the neurosurgeon's reporting that "…there is no reason to believe that exposure to chlorine fumes caused the leak" and the limited medical literature regarding the development of a fistula as a result of coughing. The WCB medical advisor noted that their own review of the medical literature had found the same result, and agreed with the previous WCB medical opinion on file that the worker's diagnosis of intracranial hypotension due to CSF-venous fistula was not medically accounted for in relation to the November 12, 2014 workplace accident. On April 17, 2023, the WCB provided the worker with a decision letter advising there would be no change to the earlier decisions they were not entitled to further benefits.

On April 27, 2023, the worker submitted further medical evidence to Review Office and requested reconsideration of the WCB's decision. The worker noted their treating neurologist, in a letter to their representative on November 8, 2017, theorized that it was possible the worker's severe coughing bout from the November 12, 2014 workplace accident may have resulted in a leak from one of several congenital pseudomeningoceles (abnormal collections of CSF) that had been identified on testing. The worker noted no evidence had been provided to indicate this event did not happen and as such, they should be entitled to further benefits.

Review Office determined on June 9, 2023, the worker was not entitled to further benefits in relation to the November 12, 2014 workplace accident. Review Office agreed with and accepted the opinions of the WCB medical advisors that medical evidence did not support a connection between the worker's diagnosis of intracranial hypotension and the workplace accident. Review Office also found the evidence did support that the possible leading cause for the worker's diagnosed probable CFS leak was congenital and pre-existing health conditions.

The worker's representative filed an appeal with the Appeal Commission on June 3, 2025 and a hearing was arranged.

Reasons

Applicable Legislation and Policy

The Appeal Commission and its panels are bound by the provisions of The Workers Compensation Act (the “Act”), regulations under the Act and the policies established by the WCB's Board of Directors. The provisions of the Act in effect as of the date of the worker’s accident are applicable.

A worker is entitled to benefits under Section 4(1) of the Act when it is established that a worker has been injured as a result of an accident at work. Section 4(2) of the Act states that a worker injured in an accident is entitled to wage loss benefits for the loss of earning capacity resulting from the accident, but no wage loss benefits are payable where the injury does not result in a loss of earning capacity during any period after the day on which the accident happens.

When the WCB determines that a worker has sustained a loss of earning capacity, an impairment or requires medical aid because of an accident, compensation is payable under Section 37 of the Act. Section 39(2) of the Act sets out that wage loss benefits are payable until the worker's loss of earning capacity ends or the worker attains the age of 65 years. Section 27 of the Act allows the WCB to provide medical aid “as the board considers necessary to cure and provide relief from an injury resulting from an accident.”

The WCB has established Policy 44.10.20.10, Pre-existing Conditions (the "Policy"), which addresses eligibility for compensation in circumstances where a worker has a pre-existing condition. The Policy defines a pre-existing condition as any medical condition the worker had prior to their workplace injury, and notes that pre-existing conditions may contribute to the severity of a workplace injury or significantly prolong a worker's recovery. It is further noted that workplace injuries can impact pre-existing conditions.

A temporary worsening of a worker’s pre-existing condition is considered an aggravation of the pre-existing condition and a permanent worsening of the worker’s condition because of a workplace injury is an enhancement of the pre-existing condition.

The Policy provides that wage loss benefits will cease when a worker has recovered to the point that the injury is no longer contributing to a material degree, to the worker's loss of earning capacity, and the pre-existing condition is not a compensable condition.

Worker’s Position

The worker was represented at the hearing by counsel who provided an oral submission. The worker attended the hearing and gave evidence in response to questions asked of them.

The worker’s position was that the coughing fit they experienced in the immediate aftermath of chemical inhalation on November 12, 2014 directly caused them to develop intracranial hypotension. The worker submitted that they are therefore entitled to further WCB benefits.

The worker noted that they did not begin to suffer intractable and debilitating headaches until January of 2015, approximately 6-8 weeks after their coughing fit at work. The worker indicated that this timing fits with their understanding of how long it would take for a gradual depletion of CSF to cause symptoms of intracranial hypotension.

The worker also noted that they had a brain MRI study for reasons unrelated to their WCB claim on January 15, 2014, several months before their accident injury, which showed no evidence of intracranial hypotension. The worker argued that the relevant intervening event between the normal 2014 MRI and the 2015 MRI which showed intracranial hypotension was the accident and related coughing fit of November 12, 2014.

When questioned, the worker confirmed their position that it was the coughing fit rather than toxicity of chemical exposure that, in their view, caused the continuing injury for which they seek benefits. Counsel for the worker noted that if the worker’s coughing fit had activated or worsened pre-existing medical conditions, the worker would be entitled to benefits pursuant to WCB policy.

The worker pointed to various statements made by their treating medical professionals since their diagnosis indicating the possibility that a coughing fit as described by the worker could have led to depletion of CSF and intracranial hypotension. The worker argued that because there is no evidence their coughing fit did not cause intracranial hypotension, and because medical opinions on file indicate that it could have, they are entitled to further benefits from WCB.

The worker also argued that the absence of cases in medical literature where coughing has led to the worker’s condition is not determinative of the issue. The worker noted that the first recorded case of a CSF-venous fistula was not identified until 2013, and research on the condition is consequently limited. It is therefore unsurprising that there are no reported cases of vigorous coughing (Valsalva maneuver) as the cause of a CSF-venous fistula.

Employer’s Position

The employer did not participate in the appeal.

Analysis

The issue on appeal is the worker’s entitlement to further benefits arising out of the workplace accident of November 12, 2014. For the appeal to succeed, the panel would have to find that the worker had a loss of earning capacity or required medical aid as a result of injuries sustained in the accident of November 12, 2014. For the reasons outlined below, the panel was not able to make such a finding and therefore the worker’s appeal is denied.

The issue for the panel’s consideration is whether the worker, on the balance of probabilities, developed intracranial hypotension as a result of the accident of November 12, 2024. There is no dispute as to the worker’s diagnosis, which was confirmed by repeat testing after 2015.

The panel has carefully considered the medical information provided by the worker’s treating neurologists. We note that in a report dated November 8, 2017, the worker’s then treating neurologist confirmed MRI evidence of intracranial hypotension and multiple spinal pseudomeningoceles, and wrote:

Generally, when we see this MRI finding in a patient, we assume that the pseudomeningoceles are congenital in nature although I do not have any definitive proof in [the worker’s] case that this is so, and that the reason for the intracranial hypotension is that one or multiple of the pseudomeningoceles have developed a spontaneous CSF leak.

I did mention that it was theoretically possible that during her severe coughing bout from the “chlorine gas” may have resulted in one of the congenital pseudomeningoceles leaking. This of course is a hypothesis and there is no way to provide any definitive proof.

Therefore, the best way to think about this is that the patient had in all probability congenital psuedomeningoceles at which point one or multiple of them resulted in a spinal fluid leak that was the cause of [their] intracranial hypotension.

As the site of a CSF leak had not been identified and the worker continued to experience symptoms, various testing and treatments continued to be explored by the worker’s treating medical professionals after the date of this report.

In a report dated February 11, 2022, a subsequent treating neurologist for the worker wrote:

There is no reason to believe that exposure to chlorine fumes caused the leak. However, given that [the worker] had a “coughing fit” for half a day, this theoretically could have resulted in the spinal dural tear or theoretically even development of a CSF venous fistula. While it is reasonable to speculate that coughing may have been a provoking factor, it is not provable. In addition, coughing alone would be unlikely to be the sole mechanism. The underlying connective tissue weakness at a diverticula site, which is something either developmental or longstanding in nature, would be an additional factor, and of course, not work related. However, if there is an underlying weakness of the dura, as reflected by the presence of a nerve root sheath diverticulum, which is not an uncommon incidental finding in many patients who undergo MRI of the spine, then a coughing fit may contribute to a tear at the nerve root sheath.

The neurologist conducted further testing in an effort to identify the source of the worker’s CSF loss. As described in the neurologist’s report dated June 13, 2022, myelogram testing “demonstrated findings highly suspicious for a CSF venous fistula at the right T8-9 level”.

Having identified the probable CSF-venous fistula, the neurologist wrote in a report dated November 24, 2022,

…I can only state that hypothetically severe coughing, or any other type of Valsalva maneuver, might expand a channel draining CSF into veins creating a fistula… The time course of [the worker’s] symptom development in relation to the chlorine gas exposure and severe coughing would fit with such a mechanism. However, I told [the worker] I have no way of proving this idea. The first case of a CSF-venous fistula was only described recently (2013). I am not aware of any cases in the limited literature available describing the development of CSF-venous fistulas as a result of Valsalva maneuvers [coughing], which of course does not exclude this possibility.”

The panel acknowledges that two of the worker’s treating neurologists have noted, as set out in the report excerpts reproduced above, the theoretical possibility that the worker’s coughing fit on November 12, 2014 could have caused the worker to develop intracranial hypotension. However, no medical evidence was provided to the panel which indicated the worker’s coughing fit was the “probable”, as opposed to “possible”, cause of the worker’s condition.

The panel notes that the two treating neurologists also provided evidence, as set out in the report excerpts reproduced above, indicating that the worker’s physiology and pre-existing condition(s) may have caused or contributed to the worker’s intracranial hypotension.

The panel is unable to determine that the evidence, on a whole, establishes a probable causal connection between the worker’s coughing fit and their development of intracranial hypotension. We note that a fit of coughing, even as described by the worker, is a rather common event, and relatively unremarkable. The panel must therefore consider that other commonplace events might also have caused and/or contributed to the condition.

We are satisfied on the evidence that factors other than coughing, including the worker’s physiology and/or other situational factors, are equally likely to have caused the worker’s condition. This is the case even having regard to the timing of the worker’s coughing fit in relation to their diagnosis of intracranial hypotension, which we have also carefully considered.

For the worker’s appeal to succeed the panel would have to determine that the worker’s medical condition was, more likely than not, caused by the workplace accident of November 12, 2014. Based on the evidence before us and on the standard of a balance of probabilities, the panel is not able to find a causal connection between the worker’s November 12, 2024 accident injury and the worker’s diagnosis of intracranial hypotension. The worker is therefore not entitled to further benefits in relation to the accident, and the appeal is denied.

Panel Members

M. Murray, Presiding Officer
J. Peterson, Commissioner
M. Kernaghan, Commissioner

Recording Secretary, J. Lee

M. Murray - Presiding Officer
(on behalf of the panel)

Signed at Winnipeg this 14th day of October, 2025