The knee-jerk, ankle-jerk and plantar reflexes are being examined in this patient. There is a slight down-going plantar reflex on the right side. Otherwise, all other reflexes are absent.
Discussion of the sign
Areflexia may indicate deficits in the reflex loop. This may be due to a lesion involving the sensory neuron or the lower motor neuron in which the location of the pathology may be at the peripheral nerve, spinal roots or the spinal cord.
Neuropathy is an important cause of this sign. There may be an isolated peripheral nerve lesion, as in peripheral nerve injuries or radiculopathies; or patients may have multiple nerves involved such as mononeuritis multiplex or peripheral neuropathy. This patient presented with an ascending weakness involving the four limbs and was noted to be areflexic. She was subsequently diagnosed to have Guillain Barré syndrome.