Spinal Cord and Root Disease
A 57-year-old woman began having weakness and trouble walking 1 year ago. Current examination findings include weak, wasted muscles with spasticity, fasciculations, extensor plantar responses, and hyperreflexia. Which of the following is the most likely diagnosis?
a. Dorsal spinal root disease
b. Ventral spinal root disease
c. Arcuate fasciculus damage
The answer is d. Motor neuron disease in the anterior horns of the spinal cord and damage to the corticospinal tracts or motor neurons contributing axons to the corticospinal tracts would account for these neurological signs. Damage to the dorsal spinal root would be expected to produce sensory, rather than motor, deficits and would produce areflexia, rather than hyperreflexia, at the level of the injury. Damage to the ventral spinal roots would produce weakness and wasting, but no spasticity or hyperreflexia would develop. Purkinje cell damage would be expected to produce ataxia without substantial weakness. The arcuate fasciculus connects elements of the cerebral cortex not involved in the regulation of strength or motor tone.
Which of the following is the most likely spinal cord pathology evident on this T1-weighted magnetic resonance image (MRI)?
The answer is b. The sausage-shaped structure in the spinal canal is a syrinx extending from C2 down into the thoracic spinal cord. This is filled with a fluid that appears similar to CSF on MRI. That this patient has syringomyelia independent of neoplasia, infarction, or intraspinal hemorrhage is suggested by the protrusion of cerebellar structures below the foramen magnum. The combination of a low-lying vermis or cerebellar tonsils and syringomyelia points to a Chiari malformation. Although it is inapparent on this MRI scan, the posterior fossa would be expected to be abnormally small, and the tentorium cerebelli would insert relatively low on the cranium. Other spinal or spinal cord problems, such as spina bifida and tethered spinal cord, would not be unusual features in association with a Chiari malformation. Even an imperforate anus might be found in the infant with a Chiari malformation, but damage to the cord sufficient to produce paraplegia is most likely with a lumbosacral myelomeningocele. With this lesion, there is a defect in the dorsal aspect of the spinal column with an attendant outpouching of meninges and neural elements from the spinal cord. Potential treatment modalities of syringes ...