Cervical Spondylotic Myelopathy

Cervical spondylotic myelopathy refers to degenerative disc disease and bony changes leading to compression of the spinal cord.  This remains one of the most common causes of spinal cord dysfunction in individuals over 50 years of age.  During the early stage of the disease process, spinal cord compromise is often overlooked due to the intermittent and subtle nature of the symptoms.  One of the earliest symptoms of spondylotic myelopathy is a disturbance of gait or the inability to walk efficiently.  Abnormal gait and altered balance due to spinal cord compromise can lead to increased risk for falling leading to hip and/or spine fracture. 

Chronic abnormal patterns of neck movement contribute to bone spur formation that can result in narrowing of the spinal canal.  Spinal stenosis can compress adjacent blood vessels supplying the spine and spinal cord, as well as directly compresses nerve tissue of the spinal cord.  Progressive thickening and bone spurring compresses the spinal cord and nerve roots, leading to progressive signs and symptoms. 

Individuals who develop cervical spondylotic myelopathy often acquire an unsteady pattern of walking, stooped neck posture and a wide-based, kind of a jerky gait.  Individuals with myelopathy often experience poor balance and unsteadiness on their feet and some loss of fine motor coordination or manual dexterity.  With more severe involvement, an individual may acquire a loss of bladder control.  Abrupt onset or progressive spinal cord compromise often requires medical management and surgical decompression of the spinal cord to reduce the risk for progressive spinal cord compromise and related disability.  

Aging and Vertebral Bone Strength

The vertebral bone achieves peak bone mass and strength in individuals between the ages of 18-25 years.  The bony vertebra are encased a thick bony outer shell, referred to as the cortex which is approximately 400-500 microns thick.  The vertebral strength is generally, determined by four primary factors.

1.         Vertebral body size,

2.         Vertebral end-plate thickness,

3.         Cortical thickness,

4.         The density of internal (trabeculae) network within the bone.

Aging influences each of these four factors. Compromise of any one or more of these factors can lead to weakening of the vertebrae.  Changes in the relationship between chemicals in the bone combined with the accumulation of small sometimes almost microscopic fractures within the bone can lead to bone fatigue and failure.