Ch 14 Spine and Spinal Cord Flashcards
(19 cards)
What is the most common level for spondylolisthesis?
L5/S1 > L4/L5
What level will a rolled up disc affect in a patient with spondylolisthesis?
The exiting nerve roots (not the transiting) - as the disc rolls upwards under the pedicle of the vertebra above.
What is the classification of spondylolisthesis?
Isthmic, dysplastic, degenerative, traumatic and pathologic.
What is isthmic spondylolisthesis (spondylolysis)?
This is a failure of the neural arch manifesting as a defect in the pars. The three types of isthmic spondylolisthesis are: lytic, elongated and acute fracture.
What causes a lytic isthmic spondylolisthesis?
Fatigue fracture of the pars.
What causes an elongated isthmic spondylolisthesis?
The pars interarticularis is intact due to repetitive fractures and healing.
What is a dysplastic spondylolisthesis?
This is a congenital defect in which there is a spondylolisthesis but no pars fracture.
What is a degenerative spondylolisthesis?
Due to long standing intersegmental instability. No pars fracture.
What is a traumatic spondylolisthesis?
Due to fractures of the VB that extend to the pars
What is a pathological spondylolisthesis?
Those that are secondary to a localised or generalised bone disease.
How does isthmic spondylolisthesis present?
With radiculopathy and rarely canal stenosis as the posterior elements remain in the same position and the VB moves forwards. The disc then rolls upwards and compresses the roots under the pedicle above.
How should isthmic spondylolisthesis be managed?
If sclerotic margins around the pars defect then there is little chance of healing and virtually no risk of progression. Surgery is reserved for neurological deficit. Lesions without sclerosis that show increased uptake on SPECT should have surgery if no neurological deficit (decompression and fusion).
What is the role of needle EMG for low back pain?
Can be used to assess acute and chronic root dysfunction, myelopathy and myopathy. Only reliable when symptoms >4 weeks.
What is the H-reflex?
Equivalent to a stretch reflex. Stimulation of a sensory nerve passes back to the dorsal columns and then to motor fibres and causes the muscle to contract which is measured on EMG. Used mostly to assess S1 radiculopathy.
What are fibrillation potentials?
These are due to independent firing of individual muscle fibres due to denervation. 3-4 weeks post injury.
What are the features of reinnervation on EMG?
Once a nerve begins to reinnervate the muscle there are larger motor units resulting in longer duration and decreased numbers.
What is an F-wave?
Motor nerve stimulation causes orthodromic and antidromic conduction. The antidromic stimulation comes back from the anterior horn and stimulates the muscle. This is prolonged in radiculopathy.
What is the classical EMG finding for myotonia?
“Dive bomber” sound due to myotonic discharges
Why are SNAPs normal with lumbar disc disease?
Because the compression is proximal to the DRG (which is in the neural foramen)
