No, long tract signs (motor or sensory) do not localize a lesion well unless they are intersected by other focal signs (e.g., cortical dysfunction, cranial nerve or brain stem signs, lower motor neuron dysfunction, deep tendon reflex abnormalities, etc.) (see slide #1).2. What regions, levels, and/or structures of the nervous system are involved with signs or symptoms of lower motor neuron (LMN) disease?
a. Mild atrophy and weakness of the thenar eminence muscles bilaterally
These signs are most likely caused by compression of the median nerves bilaterally at the wrist due to the patient’s need to support her weight with her hands on her walker (or cane) (i.e., bilateral carpal tunnel syndrome). This is supported by the pattern of the mild sensory signs and symptoms, which conforms to a median nerve distribution.
a. Brisk jaw jerk reflex
Corticonuclear (corticobulbar) tracts above the mid-pons
b. Hyperreflexia, including Hoffmann’s signs, in both upper limbs4. The findings in this case represent a classic neurologic syndrome. What is the name of this syndrome?
Corticospinal tracts above the cervical (C5) spinal cordc. Increased muscle tone (spasticity), hyperreflexia, extensor plantar reflexes in both lower limbs
Corticospinal tracts above the lumbar spinal cord
d. Weakness in both lower limbs
Corticospinal tracts above the lumbar spinal cord. The pattern of the weakness suggests an upper motor neuron process.
Motor neuron disease: Primary lateral sclerosis (PLS) type5. In general, what type of pathologic process is involved in this case?
Neurodegenerative process involving loss of UMN cell bodies (including giant pyramidal cells [Betz]) in layer 5 of the precentral gyrus and premotor area (areas 4, 6) of the frontal lobes, degeneration of the corticospinal tracts, and preservation of the alpha motor neurons (LMNs) in the cranial nerve motor nuclei and anterior horns of the spinal cord.6. What diagnostic procedure(s) would you undertake at this point?