NeuroTeach 36 - Inverted & Perverted Reflexes

Inverted & Perverted Reflexes

The first description of the paradoxical (inverted) triceps reflex

French neurologist Alexandre-Achille Souques (1860–1944)

2) Definition

“elicitation of the movement opposite to that normally seen when the reflex is elicited”

3) Mechanism

“a lesions simultaneously affecting the roots and spinal cord” Damaged root - interrupt local reflex - absence of contraction Damaged spinal cord - interrupt corticospinal tract - hyperactive response of the lower spinal segment

4) Why is there a hyperactive response?

5) Inverted radial (supinator) reflex

Level of pathology: C5/6 Positive response: Flexion of fingers and extension of elbow rather than elbow flexion when eliciting the supinator (brachioradialis) jerk.

6) Inverted radial (supinator) reflex

7) Inverted radial (supinator) reflex

8) Inverted radial (supinator) reflex

9) Paradoxical (inverted) triceps reflex

Level of pathology: C7/8 Positive response: Flexion of elbow rather than extension when eliciting the triceps jerk.

10) Paradoxical (inverted) triceps reflex

11) Paradoxical (inverted) triceps reflex

12) Inverted biceps reflex

Level of pathology: C5/6 Positive response: Extension of elbow rather than flexion when eliciting the biceps jerk.

13) Inverted knee jerk

Level of pathology: L2/3/4 Positive response: Flexion of knee (hamstring contraction) rather than knee extension when eliciting the knee or quadriceps jerk.

14) Special

Absent quadriceps reflex with distant toe flexor response Level of pathology: L3/4

15) Clinical clues

C5 lesion – inverted biceps C6 lesion – inverted radial C7 lesion – inverted triceps