Objective: Degenerative cervical myelopathy (DCM) is a progressive spinal cord disorder, yet modifiable risk factors that accelerate its progression remain poorly understood. While cigarette smoking worsens surgical outcomes, its influence on disease progression under conservative management is unclear. This study examined the effects of combustible cigarette and Heated tobacco products (HTPs) extracts on cervical myelopathy progression. 

Methods: Male Sprague–Dawley rats underwent cervical spinal cord compression surgery and received intraperitoneal injections of saline (CM), cigarette smoke extract (cCM), or HTP extract (hCM) every 5 days for 10 weeks. Motor and sensory function were assessed using the Basso, Beattie, and Bresnahan (BBB) scale and the von Frey test. Histological evaluation was performed postmortem. In vitro, differentiated PC12 cells were exposed to cigarette smoke extracts from combustible cigarettes or HTPs, and neurite length, cell viability, and apoptosis were assessed. 

Results: BBB scores at postoperative 10 weeks were significantly lower in the cCM and hCM groups than in the CM group. Hind paw withdrawal thresholds were significantly higher in the cCM and hCM groups. Histological analysis revealed neuronal loss, gray matter cavitation, and white matter demyelination. In PC12 cells, both extracts significantly reduced neurite length and viability and increased apoptosis, accompanied by oxidative stress–associated mitochondrial dysfunction. 

Conclusions: Both combustible cigarette and HTP extracts exacerbated neurological deterioration in a cervical myelopathy model. HTPs, despite their perceived safety, exerted detrimental effects comparable to those of combustible cigarettes. These findings highlight the need to address all forms of tobacco use in patients with DCM receiving conservative treatment.