Why this natters: the Thin Skull Rule

Under settled workers' compensation principle, a pre-existing vulnerability does not defeat a claim where a
workplace event triggers, aggravates, or accelerates that vulnerability into a disabling condition — the
employer, and the compensation system, take the worker as they find them. A noise level being “not hazardous
to hearing” in an audiological sense does not answer the Separate question of whether that same noise, in this
worker, triggered a migraine and tension cascade severe cnough to cause his first-ever emergency migraine
presentation, Ms, Pang's own quoted record already answers that second question; the treating ENT specialist
said it did. An audiologist's assessment of hearing-hazard levels is not a basis to overrule that specialist's causal
impression, and neither the Opinion nor the TELUS Health submission identifies any medical basis on which it
does so.

§. The Prescription Record: A Stable Bascline, Disrupted at the Moment of Exposure

The worker's prescription claims history, obtained from his extended health benefits provider, was not before
Ms. Pang and is not addressed in either submission. It is directly relevant to the conclusion that the worker's
presentation is driven by “pre-existing” factors,

For the approximately seventeen months before January 12, 2026 (August 2024 to November 2025), the
worker's prescription record consists of exactly two medications: sumatriptan, an acute migraine medication,
filled at consistent roughly three-month intervals (August 2024, November 2024, February 2025, May 2025,
August 2025, November 2025), and bilastine, an allergy medication, filled monthly without interruption. No
other medication appears in this seventeen-month record.

On January 31, 2026 — within days of the OMC! exposure and the onset of ear pain on January 23, 2026 —
an emergency department physician prescribed sumatriptan, prednisone, and pantoprazole as part of treating
the worker's acute presentation, corresponding to the same Royal Columbian Hospital attendance described in
Section 7, above. This was not a routine refill: it Was an emergency prescription, approximately eleven weeks
afier the worker's previous sumatriptan fill — at the edge of, not outside, his established three-month pattern,
but issued in an emergency department rather than through routine care.

Following that attendance, the prescription record changes materially. Sumatriptan fills accelerate to
four-to-five-week intervals (February 25, April 1, and April 28, 2026). More significantly, four medications
appear in the worker's record for the first time in the entire seventeen-month period, beginning in February and
March 2026, and have continued monthly since: quetiapine (first filled February 5, 2026), and trazodone,
sertraline, and risperidone (each first filled March 4-5, 2026). None of these four medications appears
anywhere in the worker's prescription history before the exposure period.

The worker submits this is the relevant evidentiary record: a stable, two-medication baseline for at least
seventeen months, followed by emergency-room initiation of acute migraine treatment within days of a
documented occupational exposure, followed by an entirely new regimen of psychiatric medications sustained
without interruption for. over four months. This medication history, its timing, and its composition are not
addressed anywhere in either submission. The worker notes this regimen was assembled reactively across
multiple emergency department visits rather than through coordinated psychiatric: care, and that he has since
been referred to the Mental Health Unit at Royal Columbian Hospital, with a virtual psychiatric consultation
scheduled for July 13, 2026 to review and coordinate it.

Source: Prescription claims history, extended health benefits provider, -ingust 2024—present,

9. The Autistic Sensory Profile: Why This Exposure Mattered, Not Why It Should Be
Dismissed

‘The Opinion references the worker's heightened Sensory sensitivity as part of the “pre-existing and
non-occupational” picture used ta explain his symptoms away from occupational causation. The TELUS
Health submission repeats this framing without independent analysis. Both treat the sensory profile as a reason
the claim should-not succeed. That is the reverse of its actual evidentiary function,

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