Surgical Decision-Making in Cubital Tunnel Syndrome Stratified by Electrodiagnostic Severity: A Reproducible Markov Model With Probabilistic Sensitivity Analysis.

Background Cubital tunnel syndrome is the second most common compressive neuropathy of the upper extremity. Existing decision analyses generally use simplified decision-tree frameworks. They do not stratify by electrodiagnostic severity and do not model medial antebrachial cutaneous (MABC) nerve morbidity as a durable health state. We developed a reproducible Markov model comparing simple decompression (SD) and transmuscular anterior transposition (TMT), stratified by demyelinating versus axonal disease. Methods A five-cycle annual Markov cohort model was constructed from the societal perspective with 3% annual discounting. Patients entered the model as mild/moderate demyelinating or severe/axonal cubital tunnel syndrome. MABC injury was modeled as a permanent state with an annual utility decrement. Probabilistic sensitivity analysis (PSA) used 10,000 Monte Carlo iterations, beta distributions for probabilities and utilities, and gamma distributions for costs. A complete Python implementation is provided as supplementary material. Results In the reproducible implementation, SD remained the preferred strategy in mild/demyelinating disease, with higher mean five-year quality-adjusted life year (QALYs) and lower mean cost than TMT. In axonal disease, TMT produced a small mean QALY advantage but remained close to equipoise, with overlapping credible intervals and a higher mean cost. The MABC risk differential narrowed in axonal disease because the SD pathway has greater downstream revision exposure. These findings support SD for demyelinating disease without subluxation and support individualized discussion of TMT in axonal disease rather than a categorical claim of superiority. Conclusions This model supports a stratified approach based on electrodiagnostic severity while emphasizing the uncertainty in axonal disease. The strongest conclusion is not that TMT is universally superior in axonal cubital tunnel syndrome, but that the tradeoff changes when revision risk and MABC morbidity are modeled over time. The model is hypothesis-generating and should be validated with prospective electromyography (EMG)-stratified outcome data.