A 65-year-old man presented with neck pain and right arm weakness and tingling. Examination displayed grade 3/5 weakness of the right triceps and a C7 dermatome sensory loss. Triceps reflex testing elicited flexion rather than extension of the forearm (video 1). MRI demonstrated a large C6-C7 disc indenting on the thecal sac anteriorly and compressing the C7 root on the right side (figure). Spreading of the reflex to an adjacent myotome is a sign of cord injury with pathologic sensitization of the intrinsic cord circuitry. Inverted reflexes were also described in the knee1 and brachioradialis.2
Video 1
Inverted triceps reflex. Triceps reflex testing elicited flexion rather than extension of the forearm.Download Supplementary Video 1 via http://dx.doi.org/10.1212/010182_Video_1
Sagittal (A) and axial (B) T2-weighted imaging of the cervical spine demonstrating protruded discs at C4-C5 and C6-C7 narrowing the spinal canal (sagittal) and right foraminal disc protrusion impinging the C7 nerve exit (axial).
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- © 2020 American Academy of Neurology
Disputes & Debates: Rapid online correspondence
- Reader response: Absent triceps reflex with forearm flexion: A new form of inverted reflex
- Reader response: Absent triceps reflex with forearm flexion: A new form of inverted reflex
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