Which of the following grades of deep tendon reflexes best describes a patient with transient
and intermittent clonus?
- a.Grade 0
- b.Grade 1+
- c.Grade 2+
- d.Grade 3+
- e.Grade 4+
Answer to the clinical question above:
The answer is (e).
Clonus is rapidly alternating involuntary contraction and relaxation of skeletal muscle. Using a reflex hammer deep tendon reflex (DTR) response is graded on a scale from 0 to 4+:
In a normal person, when a muscle tendon is tapped briskly, the muscle immediately contracts due to a two-neuron reflex arc involving the spinal or brain stem segment that innervates the muscle. The afferent neuron whose cell body lies in a dorsal root ganglion innervates the muscle or Golgi tendon organ associated with the muscles; the efferent neuron is an alpha motor neuron in the anterior horn of the cord.