Nevertheless, in General Foundry Service v. WCAB (Jackson) (1986) 42 Cal. 3d 331, the California Supreme Court created an exception to the five-year limitation period for cases involving insidious, progressive diseases. In Jackson, it explained that permanent disability as it had been defined could not adequately apply to such diseases because of their progressive nature. So, it concluded that “the Board’s reservation of jurisdiction on the issue of permanent disability in the case of insidious, progressive diseases serves to further the compensatory goals of the workers’ compensation system.”

Jackson explained that in dealing with insidious, progressive diseases, the appeals board could tentatively rate an applicant’s permanent disability and order advances based on that rating. It may then reserve jurisdiction for a final determination of PD when either: (1) the applicant’s condition becomes permanent and stationary, or (2) the permanent disability is total and further deterioration would be irrelevant for rating purposes.

Following Jackson, in Ruffin v. Olson Glass Co., Inc. (1987) 52 CCC 335, 342, the appeals board en banc held that an “insidious, progressive disease” has these characteristics: (1) it’s caused by a “remote” and “undramatic” work exposure –– one that is unlikely to be detected at the time, or if detected, the significance is likely to be unappreciated; (2) the disease worsens over time, but at a rate so gradual that it’s well-established before becoming apparent; and (3) it has a “long latency period” between exposure to the risk and the onset of symptoms. In Ruffin, the appeals board held that insidious, progressive diseases did not include a chronic lumbosacral sprain or a degenerative knee condition. It explained that if the definition were expanded to include such claims, the limitations of LC 5804 and LC 5410 would cease to have any effect.

Since then, the appeals board has held that insidious, progressive disease could include asbestosis, certain types of cancer, Valley fever and hepatitis C –– diseases that could be characterized as being caused by exposure to something harmful. Previously, it had rejected efforts to include orthopedic injuries or injuries caused by trauma as insidious, progressive diseases.

Recently, however, in Oliver v. Tampa Bay Buccaneers, 2022 Cal. Wrk. Comp. P.D. LEXIS 251, the appeals board held that chronic traumatic encephalopathy (CTE) could qualify as an insidious, progressive disease. In that case, a professional football player alleged injury to multiple body parts, including his head, neck and back. Both the treating physician and neurological qualified medical evaluator (QME) found the applicant’s head trauma and presumed CTE to be progressive. The QME reported that his mental capacity from a combination of his Parkinson’s disease, dementia and the beginning of presumed CTE (CTE cannot be diagnosed officially until postmortem) would lead to a progressive deterioration in his mental function over time. The treating physician also concluded that the applicant’s head trauma resulted in CTE, with continuing deterioration of his symptoms.

The board found that the factors in Ruffin supported a finding that the CTE of the applicant in Oliver was an insidious, progressive disease. Although the multiple head injuries he incurred over his years of playing football ultimately caused his post-traumatic head syndrome and CTE, the disease was not detected until many years after he stopped playing. Also, although it was not clear to what extent the applicant’s neurological disability has worsened, the QME was clear that his head trauma would lead to a progressive deterioration in his mental function over time. Although the appeals board rejected the applicant’s argument that his condition left him permanently totally disabled, it concluded that reserving jurisdiction over his neurological permanent disability was justified.

So, the appeals board has held that a condition caused by physical trauma could be an insidious, progressive disease.

The board, however, does not open the door for all routine orthopedic injuries to be so characterized; it dealt with a unique condition –– CTE –– involving injury to the brain. Whether other brain injuries could qualify as insidious, progressive diseases will need further legal development, although they would have to qualify under the factors in Ruffin.