Workers’ Compensation · Primary-source case analysis

Hikida: Disability Caused by Industrial Medical Treatment Was Not Apportioned

By Aneeta Mishra and Timothy Chan

Published April 21, 2026

Hikida distinguishes causation of the original injury from disability that flows directly from authorized medical treatment for that injury.

A repetitive injury led to failed surgery

After decades of clerical work, Maureen Hikida developed carpal tunnel syndrome and underwent authorized surgery. The procedure produced chronic regional pain syndrome and left her permanently totally disabled.

The Board apportioned to underlying causes

The medical evaluator attributed much of the carpal tunnel condition to nonindustrial factors. The WCAB used that allocation to reduce the permanent-disability award even though the evaluator tied the total disability to the surgical complication.

Treatment consequences remained compensable

The court applied the rule that an employer is responsible for new injury and disability resulting from medical treatment of an industrial injury. The 2004 apportionment amendments did not expressly eliminate that principle where the disabling condition was the treatment consequence itself.

Disposition

The court annulled and remanded for an unapportioned award of permanent total disability. Later cases require careful attention to Hikida’s treatment-caused-disability rationale rather than treating it as a universal bar to apportionment.

Key takeaways

• Identify the medical cause of disability, not only the cause of the original injury.
• Separate underlying pathology from a new treatment consequence.
• Obtain medical findings that explain the causal sequence.
• Read later apportionment decisions before applying Hikida broadly.