Cervical Spondylotic Myelopathy

05 November 2004

Degenerative disease of the lower cervical spine, narrowing the spinal canal & intervertebral foramina causing progressive injury of the spinal cord +/- roots.

1838 (Key)

2 cases of compressive myelopathy with paraplegia

spondylotic bar: a projection of the intervertebral substance (posterior ligament of the spine) which was thickened & presented a firm ridge which lessened the canal by one third

1892 (Horsley)

cervical laminectomy in patient with subacutely evolving paraplegia precipitated by trauma

found to have “transverse ridge of bone”

1948 (Brain)

“soft disc”: acute rupture & protrusion of the cervical disc more likely to compress nerve roots rather than spinal cord

“hard disc”: chronic spinal cord & root compression , consequent upon disc degeneration & osteophytic outgrowths

1957 (Payne & Spillane)

the importance of smaller than normal spinal canal in genesis of cervical myelopathy

PATHOLOGY

Spondylosis

Fraying of annulus fibrosis with extrusion of disc material into spinal canal

Disc becomes covered with fibrous tissue or partly calcified

Formation of osteophytes & transverse bony ridges

Adjacent dura thickened & adherent to post longitudinal ligament

Thickened underlying pia-arachnoid

Ligamentous hypertrophy

Myelopathy

Most marked changes in cord at level of compression

Zones of demyelination or focal necrosis

PATHOGENESIS

Intermittent cord compression

            During flexion & extension, cervical cord & dura move up down

            Dragged over osteophytes & hypertrophied ligaments

Segmental ischemic necrosis with intermittent vascular compression +/_ spasm

SYMPTOMATOLOGY

Involvement of nervous system is not always accompanied by symptoms

1.Painful, stiff neck

            75% of patients >50 yo but no neuro complaints

            radiological evidence of narrowing cervical spinal canal

                        50% of above with physical signs of root or cord involvement

2.Brachialgia / numb, clumsy hands

brachialgia worsened by cough, Valsalva,  flex/extension

Lhermitte symptoms

Atrophy of hands similar to ALS (5% incorrect diagnosis)

Numb, clumsy hand maybe due to a high cervical cord lesion

            Pinprick, touch & temp > tactile sensation

3.Spastic legs

spasticity > evident than weakness

“tabetic” unsteadiness  

INVESTIGATIONS

PROGNOSTIC FACTORS

Female

Increased cervical mobility

>30% reduction of AP diameter

MRI with T2 hyperintensity in cord

Duration of symptoms

SURGERY

Progressive impairment of function without sustained remission

Posterior approach

Advantages:      root visualization

                        Removal of fibrous constrictions around root

                        Enlargement of intervertebral foramen

Disadvantages:  increases cervical mobility

                        2-8% increase in root/cord deficit

Anterior approach

advantages:       simpler & easier decompression of roots & cord

                        removal of disc

                        intradisc transplant (fusion rate 70-100%)

surgical complications

periop mortality: 0.5 –1.5%

worsening of cord/root problem: 1-5%

CONSERVATIVE TREATMENT

Conservative treatment is rewarding for radiculopathy

            But surgical treatment is so successful, most people opt for surgery

Natural history is unknown