Thread by @theneurolander

Inverted & Perverted Reflexes

The first description of the paradoxical (inverted) triceps reflex

French neurologist Alexandre-Achille Souques (1860–1944)

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Definition

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

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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

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Why is there a hyperactive response?

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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.

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Inverted radial (supinator) reflex

doi.org/10.1212/WNL.00… via: Neurology

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Inverted radial (supinator) reflex

via: Dr Mahyuddin Mohamed

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Inverted radial (supinator) reflex

via: Oren Goltzer

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Paradoxical (inverted) triceps reflex

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

via: MedAruth

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Paradoxical (inverted) triceps reflex

doi.org/10.1212/WNL.00… via: Neurology

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Inverted biceps reflex

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

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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.

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Special

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

doi.org/10.1016/j.clin… via: Clinical Neurology and Neurosurgery

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Clinical clues

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

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