Does the atrophy of facial muscles happen?
In many sources, also in medical sources, it is mentioned that the facial muscles will suffer atrophy if the innervation is not reinstated within a year. This often makes the facial palsy patients very nervous and anxious, sometimes even desperate. This desperation can push them to go for surgical interventions.
No, facial palsy does not cause atrophy of facial muscles.
From our point of view, the atrophy of facial muscles does not happen after facial palsy. It does not matter how much time has passed since the onset. This is because the facial muscles do not receive their sensory innervation through the facial nerve.
Facial palsy only affects the facial nerve.
The facial nerve consists mostly of motor neurons, which are responsible for the movement signals. It also provides to lacrimation and salivation glands. Only the sensory (taste) signals to the first 2/3rd of the tongue are provided by the facial nerve. Which probably some of you have experienced during the acute phase of facial palsy – the disruption of the normal taste. Which, eventually, subsides after a few weeks.
The sensory signals to and from our facial muscles are conducted by the Trigeminal nerve, which is not affected by facial palsy. That is why you do not lose the sensitivity of your skin. You also do not lose the pain sensation in your face. You may feel some numbness of your facial muscles, especially in the acute phase. That is mostly because you lack movements. The Trigeminal nerve, which senses the movements, contractions, and relaxations of our muscles, lacks signals. That is why it provides the brain with a certain feeling of numbness.
How is facial nerve different from other, skeletal nerves?
Contrary to the facial nerve, if we damage the skeletal nerve, let’s say the median nerve, which innervates some muscles in our palm and arm. The median nerve and all skeletal nerves of our body that provide the movement are mixed. They consist of both sensory and motor fibers. If this nerve is damaged, then the brain does not receive any signals from the affected muscles. So neither the signals come to the muscles, nor the signals come back to the brain from the muscles.
As long as the brain cannot hear anything from the muscles, it may think “OK, this muscle is dead, this soldier is dead, that makes no sense to send him ammunition, supplies and so on and so on”. So it just starts to ignore that muscle in its nutritional and trophic processes and the muscles sustain atrophy. Atrophy – which means – mal-nutrition. So these muscles shrink and become replaced by the fibrous tissue and permanently lose their ability to function. At least partly.
– Alex Pashov
Crystal Touch Bell’s palsy clinic