Neuronopathy is the damage occurring to the neuronal body itself. This damage occurs to anterior horn cell in case of motor involvement and to dorsal root ganglion in case of sensory involvement. Anterior horn cell can be affected by motor neuron disease, spinal muscular atrophies and poliomyelitis while sensory neuronopathy can result from paraneoplastic pathology or Sjogren’s syndrome.
7. Types of Polyneuropathies:
There can be various types of polyneuropathies based on different criteria. For example neuropathy can be motor-sensory, pure motor, pure sensory and autonomic. It can also be classified as demyelinating and axonal or large-fiber and small fiber neuropathies
8. Clinical Manifestations:
It starts with tingling, paraesthesias and numbness in toes and distal feet. It then ascends proximally towards ankles and knees. Gradually muscles become weak and ankle jerk is lost. As the disease ascends upto knees fingers also start becoming numb and knee jerk is lost. In advanced cases all the 4 limbs are involved along with anterior trunk. In very serious cases intercostal nerves and nerve to diaphragm are involved resulting in breathing difficulty. Proprioception and vibration are also lost during initial stages of the disease and it results in unsteady gait.
9. Differentiation Between Axonal and Demyelinating Polyneuropathies:
Proximal and distal segments are affected simultaneously in case of demyelinating polyneuropathies while axonal neuropathies are distal symmetrical variety.
All of a sudden loss of all of the tendon reflexes is suggestive of demyelination. On the other hand axonal neuropathy results in loss of tendon reflexes in an expected order.
10. Differentiation Between Large-fiber and Small-fiber Neuropathies:
Small-fiber neuropathies result in loss of temperature and pain sensation along with some autonomic disturbance. While muscle power, tendon reflexes, proprioception and vibration remain intact in case of small-fiber neuropathies because these are functions of large-fibers.