What is Degenerative Cervical Myelopathy?
Degenerative Cervical Myelopathy (DCM), also known as cervical spondylotic myelopathy or cervical stenosis, is a condition in which the spine in the area of the neck (cervical) suffers chronic compression and degenerates over time. DCM can result from arthritis, spondylosis, a slipped disc, bone spurs, spinal stenosis, traumas or other conditions or events. It is a common disease, affecting up to 5% of the adult population.
Compression of the cervical cord eventually leads to nerve damage. While DCM is not always painful, it causes difficulty coordinating the hands, and may cause a heavy feeling, numbness, or tingling sensations in the legs, leading to reduced quality of life. Very few patients make a full recovery and have lifelong trouble walking, using their hands, and managing pain.
Gait dysfunction and DCM
Gait dysfunction is one of the first symptoms of DCM and in the early stages of the disease, usually presents as a subtle instability in gait and balance. Patients may also present with weakness or numbness in the upper extremities, reduced manual dexterity, lower extreme spasticity, neuropathic pain, and bowel or bladder dysfunction. Early diagnosis and management of DCM are critical, as delayed diagnosis and treatment can lead to greater disability. However, current methods for diagnosis rely on subjective history and clinical assessment, which challenges clinicians to accurately define the presentation of symptoms, especially when impairment can be very subtle during the early stages of the disease. Developing diagnostic tools to identify early stages of DCM are essential to appropriate treatments and interventions.
In the paper, Quantitative Assessment of Gait Characteristics in Degenerative Cervical Myelopathy: A Prospective Clinical Study, the study authors hypothesize that spatiotemporal gait parameters and eGVI – the enhanced gait variability index – could be used to determine the severity of DCM during early impairment.
The authors wished to characterize gait impairments of study participants to define and detect specific changes that resulted from progressive cervical spinal cord compression. The primary goal was to assess the correlation between subjective gait impairment in patients with DCM, measured against the modified Japanese Orthopedic Association (mJOA) score (a subjective clinical score that assesses difficulties with walking), and lower extremity subscore with objective gait parameters. The secondary goal was to characterize mild, moderate, and severe stages of DCM using quantitative spatiotemporal gait measurements.
The research study recruited 153 patients recently diagnosed with DCM who were stratified based on DCM severity grades according to the mJOA scale. Gait assessments were performed with a Protokinetics Zeno Walkway. Spearman rank correlation was used to identify relationships between gait parameters and mJOA values as well as the mJOA lower extremity subscore. Each patient walked across the Zeno Walkway mat barefoot, at a self-selected pace four times without walking aids. Gait data from the integrated pressure mat was collected with Protokinetics PKMAS software. The eGVI was used to assess the quality of each patient’s gait based on 5 spatiotemporal parameters: step length, step time, stance time, single-stance time, and stride velocity.
Conclusions of the research study
The authors concluded that the enhanced gait variability index was useful in documenting differences in severity as defined by the mJOA, particularly in velocity and step length. Patients with early and mild symptoms of DCM typically report minimal gait impairment and these gait deficits are typically not detected in routine clinical exams. Even when timed walking tests are used, gait velocity in individuals with mild DCM typically falls within a normal range and subtle gait variations cannot be quantified. Clearly, identifying these subtle gait variations in the early stages of the disease can be critical in monitoring the progression of DCM.
The research study was able to demonstrate a significant correlation between the mJOA score and various spatiotemporal gait parameters collected with PKMAS software. They also found significantly reduced velocity, stride velocity, and step length between moderate and severe groups of DCM patients.