Case 50 Answers

Basic Human Neuroanatomy

A Clinically Oriented Atlas

Case 50 Answers

1. Can this patient’s signs and symptoms be localized to one single area of the central nervous system? If so, where is the neurologic lesion located, and which side of the central nervous system is involved?

No, this is a multifocal process (see slide #1)

2. What regions, levels, and/or structures of the central nervous system are involved with signs or symptoms of lower motor neuron (LMN) disease?

a. Fasciculations and atrophy of the tongue bilaterally

Hypoglossal nuclei or nerve rootlets in the upper medulla

b. Fasciculations of the deltoid muscles bilaterally

Anterior horn cells of the C5-C6 spinal cord (doubt C5-C6 ventral roots, brachial plexus, or axillary nerve lesion)

c. Fasciculations of the quadriceps muscles bilaterally

Anterior horn cells of the L2, 3, 4 spinal cord (doubt L2-4 ventral roots, lumbar plexus, or femoral nerve lesion)

3. What regions, levels, and/or structures of the central nervous system are involved with signs or symptoms of upper motor neuron (UMN) disease?

a. Brisk jaw jerk reflex

Corticonuclear (corticobulbar) tracts above the mid-pons

b. Increased muscle tone (spasticity), hyperreflexia, extensor plantar reflexes in all 4 limbs

Corticospinal tracts above the cervical spinal cord

c. Weakness in all 4 limbs

Corticospinal tracts above the cervical spinal cord. The weakness involves a predominantly upper motor neuron pattern, but undoubtedly a lower motor neuron component is present as well.

4. The findings in this case represent a classic neurologic syndrome. What is the name of this syndrome?

Motor neuron disease: Amyotrophic lateral sclerosis (ALS) type

5. 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 the loss of LMN cell bodies in the motor nuclei of cranial nerves (especially V, VII, X, XII) in the pons and medulla and anterior horns of the spinal cord. In this patient, the hypoglossal nuclei were the only cranial nerve nuclei involved at the time of admission.

6. What diagnostic procedure(s) would you undertake at this point?

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