Natural History of Degenerative Disc Disease of Lower Cervical

Cervical spine degenerative disc disease (DDD) is more common in older individuals and can cause pain and neurological problems. A study found that over 80% of patients above 60 had disc degeneration, while less than 20% of those under 20 showed such signs.

The relationship between aging and cervical spine DDD may be influenced by other health conditions associated with age. Comorbidities like hypothyroidism, smoking, cardiovascular disease, and diabetes are linked to higher incidence of lumbar spine DDD, but their association with cervical spine DDD is unclear.

The relationship between diabetes mellitus and musculoskeletal disorders, specifically disc degeneration, is still a matter of debate. While one study over four years found a link between diabetes and upper lumbar disc degeneration, another study involving twins showed no association when considering age and BMI.

Due to the high prevalence of diabetes in the United States (9.4%), it is crucial to understand how both controlled and uncontrolled diabetes, in combination with aging and other comorbidities, impact the severity and grade of disc degeneration in the cervical spine. Moreover, the anatomical and biomechanical differences between the cervical and lumbar spine suggest that these factors may have distinct effects, requiring separate investigations.

The socioeconomic impact of low back and neck pain is significant, with cervical and lumbar spine disorders ranking among the highest healthcare expenses in the US, exceeding $85 billion annually. Understanding the factors that contribute to cervical spine degenerative disc disease (DDD) can help reduce costs and inform strategies for prevention and treatment of this common musculoskeletal condition.

The initial inclusion criteria yielded 803 patients from electronic medical records. However, due to inaccessible cervical spine MRIs, the final cohort consisted of 799 patients, with 310 diagnosed with diabetes and 489 without diabetes (Fig. 1).

The patient demographics, as shown in Table 1, indicated that both groups were predominantly of white race. Patients with diabetes were significantly older (p < 0.001) compared to those without diabetes, and they also had higher BMI values (p < 0.001).

Notably, there was no significant difference in the number of surgically fused discs between the diabetic and non-diabetic cohorts. Specifically, one patient in the non-diabetic group underwent a three-level fusion, while three patients in the diabetic group each had a single-level fusion.

Various patient-related factors, including aging, specific medical comorbidities, insurance status, and socioeconomic variables, are strongly associated with increased severity and cumulative grade of cervical spine disc degeneration (DDD).

Older age, lower median household income, previous cervical spine surgery, Medicare insurance, and certain medical conditions such as ASA classification, cancer, COPD, depression, diabetes, hypertension, hypothyroidism, peripheral vascular disease, and smoking contribute to the cumulative grade of cervical spine DDD.

Interestingly, a higher severity of disc degeneration is observed in non-white race, although it does not correspond to an increase in cumulative grade of cervical spine disc disease. These risk factors, including increasing age, diabetes, hypertension, and hypothyroidism, align with previous research findings regarding the development of lumbar spine DDD.

Currently, there is no established link between cancer, COPD, and median household income with degenerative disc disease (DDD) in either the lumbar or cervical spine.

However, bivariate analysis in this study reveals a correlation between depression and higher grade and severity of cervical spine disc degeneration. This finding is consistent with previous research that demonstrates a strong association between neck and back pain and depression, suggesting that psychological burden may be a manifestation of chronic pain.

In the multivariate analyses, older age, Medicare insurance, self-pay insurance status, and higher ASA classification are significantly associated with increased grade of cervical spine DDD. It is worth noting that diabetes is no longer significantly associated when adjusting for other factors. Additionally, older age and self-pay insurance are associated with increased severity of cervical spine DDD, as indicated by the multivariate analyses.

Considering the results of this study alongside prior research on lumbar spine degenerative disc disease (DDD), it is probable that the progression of age and the presence of associated medical comorbidities play a role in the increased severity and grade of disc disease throughout the entire spine.

Bivariate analysis demonstrates a correlation between diabetes mellitus and DDD, yet the management of diabetes does not seem to impact the severity of DDD in the cervical spine. Notably, the connections observed between declining median household income, self-pay insurance, and cervical spine disc degeneration might be influenced by vocations involving manual labor, which present elevated risks of DDD across the spine.

It is important to acknowledge the limitations of this retrospective study. The accuracy of information in the electronic medical records and the presence of medical comorbidities during MRI relied on the provided data.

The study did not specifically examine the associations between all medical comorbidities and the grade of cervical spine degenerative disc disease (DDD). The use of multiple comparisons increases the potential for chance associations, but the Benjamini-Hochberg correction was utilized to address this. The inclusion of all patients who underwent cervical spine MRI aimed to minimize selection bias.

However, the study did not evaluate pain or patient-related outcomes, making it difficult to determine the effects of medical comorbidities on symptomatic disc degeneration. Further well-designed studies are necessary to explore the relationship between disc degeneration, medical comorbidities, and patient outcomes.

Cervical spine degenerative disc disease (DDD) is influenced by patient-related factors that affect its severity and cumulative grade, similar to lumbar spine DDD. Older age, insurance status, and higher ASA classification are strongly associated with increased grade of cervical spine DDD. Diabetes is linked to higher grade and severity of cervical spine DDD as an independent risk factor, but this association diminishes when considering other medical comorbidities.

This study highlights the importance of patient demographics and medical conditions in influencing cervical spine disc degeneration, providing valuable insights for patient education and treatment.