The ankle jerk or ankle tendon reflex, also known as the Achilles reflex, takes place when the Achilles tendon is tapped while the foot is kept by the examiner in a dorsi-flexed position.
The ankle reflex can be elicited in the supine, sitting or kneeling positions. With the patient and sitting position the examiner passively dorsiflexes the patientâ€™s foot by pushing up theipatients forefoot. The Achillesâ€™ tendon is struck briskly. With the supine position the foot is similarly dorsiflxed while rotating the leg externally to expose the Achilles tendon. Using a reflex-hammer, the practitioner then strikes the Achilles tendon.
In some cases, instructing the patient to actively dorsiflex their foot can help to elicit the reflex, as this action relaxes the triceps surae. In the kneeling position the patient is asked to kneel on the edge of the examination couch. There is no need to dorsiflex the foot in this case. Thi sposition may not be adopted if the patient is elderly, frail or in severe pain.
A negative (or normal) would be the jerking of the foot towards its plantar surface, a smooth, rapid plantar flexion of the foot followed by a return to the normal resting tone of that muscle.
A positive (or abnormal) reaction would be. Excessive response or hyperreflexia indicating upper motor neurone lesion or subdued, hyporreflexia or no reflex jerk may indicated a lower motor neurone lesion. Results are best evaluated when compared with the opposite side.
The ankle or Achilles tendon reflex assesses the S1 and S2 nerve roots and classically for the presence of a herniated intervertebral disk. The test also evaluates the local spinal reflex, the corticospinal tracts and corresponding cortical regions. Tendon reflexes is graded with number of â€˜+â€™ symbols or numbered from 0 to 4.
1+ or + Hypoactive
2+ or ++ “Normal”
3+ or +++ Hyperactive without clonus
4+ or ++++ Hyperactive with clonus
If the reflexes are difficult to elicit then get the patient to perform any of the re-enforcement techniques or attempt to distract the patient. Poor execution and technique may also be blamed for poor reflexes. The tendon reflexes are uniformly delayed in hypothyroidism. Other causes or decreased reflexes or hyporeflexia include peripheral neuropathy such as in diabetes and B12 deficiency, certain medications, electrolyte imbalances (hyperkalemia and hypernatremia) Uniformly increased reflexes may be associated with hyperthyroidism, demyelinating disease, electrolyte imbalances, (e.g., hypocalcemia, hypomagnesemia) alcohol withdrawal, tetanus, anxiety, lithium overdose , Monoamine oxide inhibitor overdose, Serotonin syndrome, or a cold patient.