DEGENERATIVE CERVICAL MYELOPATHY: COMPARATIVE ANALYSIS OF POSTERIOR DECOMPRESSION TECHNIQUESABSTRACT
Objective: To compare posterior decompression techniques in degenerative cervical myelopathy (DCM) and evaluate their clinical outcomes.
Methods: A retrospective observational study was conducted on patients with DCM who underwent posterior cervical decompression surgery between 2012 and 2022. Variables analyzed included surgical time, intraoperative blood loss, and hospital stay.
Results: A total of 32 patients were included. Open surgery had a surgical time of 176.6 ± 45.3 minutes, blood loss of 300.5 ± 236.3 ml, and a hospital stay of 4.5 ± 4.4 days. Minimally invasive surgery had a surgical time of 161.5 ± 72 minutes, blood loss of 93.8 ± 69.5 ml, and a hospital stay of 1.8 ± 1 day.
Conclusions: Minimally invasive decompression resulted in shorter surgical time, reduced blood loss, and shorter hospital stay compared to open surgery. Further research is needed to determine its impact on functional outcomes. Level of Evidence II; Retrospectivef Study.
Keywords:
Spinal Cord Compression; Myelopathy; Surgical Decompression; Minimally Invasive Surgical Procedures.
RESUMO
Objetivo: Comparar as técnicas de descompressão posterior na mielopatia cervical degenerativa (MCD) e avaliar seus resultados clínicos.
Métodos: Foi realizado um estudo observacional retrospectivo em pacientes com MCD submetidos à cirurgia de descompressão cervical posterior entre 2012 e 2022. As variáveis analisadas incluíram tempo cirúrgico, perda de sangue intraoperatória e tempo de internamento hospitalar.
Resultados: Um total de 32 pacientes foi incluído. A cirurgia aberta teve um tempo cirúrgico de 176,6 ± 45,3 minutos, perda de sangue de 300,5 ± 236,3 ml e um tempo de internamento de 4,5 ± 4,4 dias. A cirurgia minimamente invasiva teve um tempo cirúrgico de 161,5 ± 72 minutos, perda de sangue de 93,8 ± 69,5 ml e um tempo de internamento de 1,8 ± 1 dia.
Conclusões: A descompressão minimamente invasiva resultou em menor tempo cirúrgico, redução da perda de sangue e menor tempo de internamento hospitalar em comparação com a cirurgia aberta. Pesquisas adicionais são necessárias para determinar seu impacto nos resultados funcionais. Nível de Evidência: II; Estudo Retrospectivof.
Descritores:
Compressão da Medula Espinhal; Mielopatia; Descompressão Cirúrgica; Procedimentos Cirúrgicos Minimamente Invasivos.
RESUMEN
Objetivo: Comparar las técnicas de descompresión posterior en la mielopatía cervical degenerativa (MCD) y evaluar sus resultados clínicos.
Métodos: Se realizó un estudio observacional retrospectivo en pacientes con MCD que se sometieron a cirugía de descompresión cervical posterior entre 2012 y 2022. Las variables analizadas incluyeron el tiempo quirúrgico, la pérdida de sangre intraoperatoria y la estancia hospitalaria.
Resultados: Se incluyó un total de 32 pacientes. La cirugía abierta tuvo un tiempo quirúrgico de 176,6 ± 45,3 minutos, una pérdida de sangre de 300,5 ± 236,3 ml y una estancia hospitalaria de 4,5 ± 4,4 días. La cirugía mínimamente invasiva tuvo un tiempo quirúrgico de 161,5 ± 72 minutos, una pérdida de sangre de 93,8 ± 69,5 ml y una estancia hospitalaria de 1,8 ± 1 día.
Conclusiones: La descompresión mínimamente invasiva resultó en un menor tiempo quirúrgico, una reducción de la pérdida de sangre y una menor estancia hospitalaria en comparación con la cirugía abierta. Se necesita más investigación para determinar su impacto en los resultados funcionales. Nivel de Evidencia: II; Estudio Retrospectivof.
Descriptores:
Compresión de la Médula Espinal; Mielopatía; Compresión de la Médula Espinal; Procedimientos Quirúrgicos Mínimamente Invasivos.
INTRODUCTION
Degenerative cervical myelopathy (DCM) is a condition caused by progressive spinal cord compression due to degenerative changes in the cervical spine.1,2 These changes include disc herniation, ligament hypertrophy, and osteophyte formation, leading to symptoms such as pain, weakness, sensory disturbances, and gait disorders.1-3 DCM is the most common cause of spinal cord disability in older adults and requires surgical intervention when conservative treatment fails.1-4
Surgical treatment consists of anterior or posterior decompression techniques, depending on the compression pattern and spinal alignment.5,6 Posterior decompression options include laminectomy, which removes posterior bony elements, and laminoplasty, which expands the spinal canal without removing bone structures.5-7 Minimally invasive techniques have gained relevance as they preserve musculature and reduce surgical trauma. However, the superiority of one technique over another in terms of clinical outcomes and functional recovery remains undetermined.6-11
This study aims to compare different posterior decompression techniques used to manage DCM and to evaluate their impact on surgical and hospital outcomes.
PATIENTS AND METHODS
Study Design
A descriptive, retrospective study was conducted from January 2012 to March 2022 in patients over 18 years old diagnosed with degenerative cervical myelopathy (ICD-10: M500: Cervical disc disorder with myelopathy, unspecified cervical region).12 Following STROBE13 recommendations, electronic clinical records were analyzed using convenience sampling.
This research adhered to the Declaration of Helsinki and the Health Research Regulations of the General Health Law.14 Patient privacy and data confidentiality were ensured by storing information in a restricted-access system.
The study was approved by the institutional review board with waiver of informed consent (Approval No. 36-2022).
Criteria Selection
• Inclusion criteria: Patients aged 18-85 years diagnosed with DCM who underwent posterior cervical decompression via laminectomy, hemilaminectomy, laminoplasty, or laminoforaminotomy, using either open or minimally invasive techniques. Only patients with complete clinical records were included.
• Exclusion criteria: Patients with rheumatic disease, peripheral neuropathy due to other causes, or non-degenerative cervical myelopathy were excluded. Patients with incomplete records or those who could not be analyzed (e.g., death from unrelated causes, poor follow-up compliance) were also eliminated.
Outcome
Patients were assessed daily during hospitalization and in outpatient follow-ups every 15 days. Outcomes were evaluated based on hospitalization duration and the Modified Japanese Orthopaedic Association (mJOA) score15 preoperatively, at six weeks, and at six months postoperatively.
Data Collection
Sociodemographic and clinical variables (affected cervical levels, number of levels involved) and surgical variables (operative time, intraoperative bleeding, hospital stay, mJOA score,16 and Nurick scale)3 were collected. Open approaches (laminectomy and laminoplasty) were compared with minimally invasive approaches (hemilaminectomy and laminoforaminotomy). Data were extracted from hospital administration records, hospitalization notes, outpatient consultations, and surgical reports.
Database structuring was performed using Microsoft Excel™ by the first and second investigators (CBQ & DAVM), while statistical analysis was conducted using IBM SPSS V21™ by a third investigator (JCLV). Missing data were reviewed via electronic radiological records (JGVC & LMO).
Statistical Analysis
Descriptive statistics were used to obtain frequencies, central tendency measures (median or mean), and dispersion measures (proportions or standard deviation) for clinical and surgical characteristics.
Kolmogorov-Smirnov tests were used to assess the distribution of the data. Central tendency and dispersion measures were applied for quantitative variables. The Kruskal-Wallis test was used for comparative analysis between treatments, while ANOVA assessed mJOA improvement at six weeks and six months. Analyses were performed using SPSS v21 and visualized in Excel. A p-value ≤ 0.05 was considered statistically significant.
RESULTS
A total of 32 patients with DCM underwent cervical decompression surgery. The majority were male (n=26, 81%), with a mean age of 70.5 ± 8.9 years (range: 52-87 years). (Figure 1)
The most affected levels were C4 (n=26, 81.2%) and C5 (n=26, 81.2%), either as singleor multi-level involvement. The most common number of affected levels was four (n=12) and two (n=9). Additional data are presented in Table 1.
According to the mJOA classification for myelopathy severity: Mild myelopathy: 14 patients (43.7%), moderate myelopathy: 7 patients (21.7%), Severe myelopathy: 12 patients (37.5%). (Table 2)
The most common imaging findings included ligamentum flavum hypertrophy, disc protrusion or herniation, facet hypertrophy, and cervical canal stenosis. Spinal cord myelomalacia (MRI, T2 hyperintensity) was observed in 18 patients (40.6%).
Electrophysiological studies were available for only 18 patients, with the most common finding being large-fiber conduction block in the posterior columns (n=7, 38.9%).
Surgical Outcomes
A total of 19 open surgeries (59.4%) and 13 minimally invasive surgeries (40.6%) were performed (Figure 2). Outcomes assessed included surgical time, intraoperative blood loss, and postoperative hospital stay. (Tables 3 and 4)
Significant differences were observed between decompression techniques: Minimally invasive techniques significantly reduced surgical time, blood loss, and hospital stay compared to open approaches.
However, Fisher’s exact test for preand postoperative mJOA scores showed that although patients undergoing minimally invasive techniques exhibited better clinical improvement, the difference was not statistically significant (p=0.166). A trend toward better postoperative function was observed in the minimally invasive group. (Table 5)
When specifically analyzing the domains assessed in the mJOA questionnaire for evaluating preoperative spinal cord impairment, the average scores obtained were upper limb motor function, µ= 3.75 ± 0.84 (SD) points and for lower limb motor function µ= 4.46 ± 1.9 (SD) points; sensory function µ=2.09 ± 0.39 (SD) points and sphincter control µ= 2.5 ± 0.91 (SD) points Among these, sensory function showed the greatest impairment.
According to the type of intervention, the following results were obtained, comparing preoperative mJOA scores with changes observed at six weeks and six months postoperatively. (Table 4, Figure 3)
Additionally, a comparative analysis of follow-up assessments using the mJOA scale demonstrated that all patients, regardless of surgical approach, showed functional improvement that remained consistent throughout the 6-month follow-up period. (Figure 4)
DISCUSSION
The primary objective of this study was to compare open surgery and minimally invasive posterior approaches for the management of degenerative cervical myelopathy (DCM). Our findings suggest that minimally invasive surgery yields better outcomes, regardless of patient age, procedure type, number of affected levels, or diagnosis.
These results align with recent literature on posterior cervical decompression for DCM.8-10,16 Previous studies have shown that minimally invasive techniques are associated with shorter surgical time and reduced blood loss compared to open procedures.17,18 Specifically, studies such as Ito et al. have reported significant reductions in hospital stay duration and postoperative pain in patients undergoing minimally invasive procedures.8-10,17-19
The reduced surgical time and intraoperative blood loss observed in this study are consistent with the findings of Soares, et al.20 who demonstrated that minimally invasive approaches better preserve paraspinal musculature and reduce postoperative inflammation, leading to faster recovery. However, despite these advantages, the functional improvement measured by the mJOA scale was not statistically significant, suggesting that effective spinal cord decompression remains the key factor in recovery, regardless of the technique used.
A critical factor to consider is patient selection for each surgical approach.21 According to Fehlings et al.,22 minimally invasive techniques are most beneficial for patients with preserved cervical lordosis and no significant spinal instability. In contrast, laminectomy with fusion remains the preferred approach in cases of kyphotic deformity or severe multilevel involvement.
Despite the observed advantages, minimally invasive techniques require a significant learning curve, which may contribute to variability in reported outcomes.18,19 Additionally, recent studies suggest that preserving the range of motion with laminoplasty may reduce the incidence of adjacent segment disease. This factor should be considered in long-term surgical planning.23-25
The results suggest that minimally invasive posterior decompression for cervical myelopathy offers significant advantages in reducing surgical time, blood loss, and hospital stay compared to open surgery.18,19,21,23-25 However, functional recovery showed no statistically significant differences between techniques, indicating that effective spinal cord decompression remains the primary determinant of patient outcomes.21,23-25
Further studies with larger cohorts and long-term follow-up are needed to determine the definitive functional impact of these techniques and establish optimal surgical recommendations for DCM patients.
These findings reinforce the clinical utility of minimally invasive techniques for posterior cervical decompression, reducing postoperative complications and promoting faster recovery. However, the lack of statistically significant differences in functional improvement highlights the need for careful patient selection and individualized surgical planning.
Limitations & Strengths
The study included only 32 patients, limiting the generalizability of the results. Also, the follow-up period was limited to 6 months, preventing assessment of long-term functional outcomes. Not all patients underwent electrophysiological studies, which may have affected the objective evaluation of spinal cord impairment.
Multiple surgical and clinical parameters were assessed, providing a comprehensive analysis of each technique’s impact.
Functional evaluation was conducted using the mJOA scale, allowing comparisons with other studies. Both open and minimally invasive techniques were analyzed, enabling the identification of variations within each surgical approach.
CONCLUSION
Minimally invasive posterior decompression techniques for DCM offer significant advantages, including shorter surgical time, reduced blood loss, and shorter hospital stays compared to open surgery. However, postoperative functional improvement did not significantly differ between techniques, indicating that effective spinal cord decompression remains the primary determinant of recovery.
Further studies with larger sample sizes and long-term follow-ups are required to determine the definitive functional impact of these techniques and establish precise surgical selection guidelines for DCM patients.
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Reviewed by: Erasmo Abreu Zardo
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Study conducted by the Central South High Specialty Hospital, Anillo Perif. 4091, Fuentes del Pedregal, Tlalpan, 14140 Ciudad de México, CDMX, México.
DATA AVAILABILITY DECLARATION
The contents underlying the research are available from the corresponding author upon request.
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