SpineTF4-Motor Neuron Disease

Clinical Profile

Findings

Discussion

Pathology

On MRI

Suggested Reading

Clinical Profile:

H/O weakness in the extremities with wasting over one year.

Findings:

There is a loss of the normal ventral bulge (flattened) of the cervical spinal cord, more so to the right over the C5 to C7 levels. Hyperintense signal, best appreciated on the GRASS axial images is seen within the cervical spinal cord, ventrally (anterior horn cells) over these levels.

Discussion: 

Motor Neuron Disease (MND) is a disorder that involves the upper and lower motor neurons. Patients usually present with weakness in the extremities, often with pain. Hyperreflexia, fasciculations and muscular atrophy may also be seen. Sensation usually remains unaffected. Weakness progresses to involve the rest of the body. Death usually occurs two to three years after onset of symptoms (mostly due to respiratory failure).

It is characterized by central motoneuron degeneration, corticospinal tract degeneration and peripheral motoneuron lesions.
Pyramidal tract involvement manifests as myelin pallor and gliosis of the lateral and anterior spinal columns. It is more marked in the lateral columns and may spread to involve the spinocerebellar tracts. Corticospinal degeneration may be seen in the medullary pyramids and occasionally in the cerebral peduncles and posterior limb of the internal capsules. In the cortical motor areas, atrophy and gliosis may be seen.
Anterior horn involvement is typical. Grossly they appear gray and retracted, and the ventral roots are atrophied. There is neuronal cell loss, more so in the cervical and lumbar enlargements.
Cranial nerve nuclei (XII, XI & motor nucleus of X) involvement may be seen.

• There is usually a loss of the ventral bulge of the cervical spinal cord. This may be bilateral or unilateral. Hyperintense signal on the T2W and GRASS axial images may be seen within the lateral columns or in the region of the anterior horn cells.

• Spinal cord atrophy may be seen.

• In the brain, hypointense signal on the T2W images may be seen in the precentral gyrus (may be due to iron deposition). Subcortical white matter tracts, centrum semiovale, corona radiata, posterior limb of the internal capsule, cerebral peduncle and pons (corticospinal tracts) may show a hyperintense signal on the Proton, T2W and FLAIR images.
  

Suggested Reading:

1. Friedman DP, Tartaglino LM: Amyotrophic lateral sclerosis: Hyperintensity of the corticospinal tracts on MR images of the spinal cord. AJR 160:604-606,1993.
2. Cheung G, Gawel MJ, Cooper PW, Farb RI, et al: Amyotrophic lateral sclerosis: Correlation of clinical and MR imaging findings.  Radiology 194(1):263-70,1995.
3. Pathology of Degenerative Diseases of the Central Nervous System. In: Poirier J, Gray F, Escourolle R: Manual of Basic Neuropathology, W.B. Saunders, pp: 139-162, 1990.