Knee jerk is a deep tendon reflex mediated by L4 segment of
spinalcord
Usually in deep
tendon reflex when a stimulus is given there is a reflex action
takes place, but in hypothyroidism the limb returns slowly to its neutral
position.That is there is slowness of the relaxation phase of deep tendon
reflexes
In hypothyroidism both the contraction and the relaxation
phases of the tendon reflex may be prolonged, which results in 'hung-up' reflexes.
Clinical significance
Hung-up reflex may be seen in
- Hypothyroidism.
- The 'hung-up' knee jerk is a specific, but rarely appreciated sign in Huntington's Disease
