Where is the Lesion

Question 1

Where anatomically are UMN lesions found?

Answer 1

Anywhere along the corticospinal tract from frontal cortex to the synapse with the anterior horn cells.

Question 2

Where anatomically are LMN lesions found?

Answer 2

Anywhere from the anterior horns distally.

Question 3

What type of paralysis to UMN and LMN lesions cause?

Answer 3

1. UMN - spastic paralysis

2. LMN - flaccid paralysis

Question 4

What are the effects of UMN and LMN lesions on reflexes?

Answer 4

1. UMN - hyperreflexia

2. LMN - hyporeflexia/areflexia

Question 5

What is the effect of UMN and LMN lesions on plantars and which causes clonus?

Answer 5

1. UMN - plantars upgoing, clonus +

2. LMN - plantars remain flexor

Question 6

Which lesion type presents with rapid wasting +/- fasciculations, UMN or LMN?

Answer 6

LMN

Question 7

Which lesion type presents with groups of muscles affected in pyramidal pattern (extensors affected in arm, flexors in leg), UMN or LMN?

Answer 7

UMN

Question 8

What is the main differential for a LMN lesion and how are they distinguished?

Answer 8

1. Myopathy

2. Myopathy tends to be symmetrical, reflexes are intact, and there is no sensory component.