What is the anatomy and physiology behind Justin Bieber’s facial paralysis?

TeachableMedicalNews article 07252022

Teachable moment in classrooms:

1. skeletal muscle chapter –functioning of skeletal muscles depend on neuromuscular junction
2. brain anatomy chapter – anatomy and function of cranial nerve VII
3. muscular system chapter – actions of muscles of facial expression
4. microbiology – viruses need to enter human cells

The news item:  A news report appeared recently:

Justin Bieber’s wife Hailey gives update after Ramsay Hunt syndrome diagnosis: ‘Getting better every day’

Justin Bieber has canceled several tour dates due to his Ramsay Hunt syndrome diagnosis. Here’s what we know about his recovery, concert plans.

The article stated that Justin Bieber is suffering from type II Ramsay-Hunt syndrome. This is caused by an activation of the Herpes Zoster virus (causes the disease called shingles) that causes paralysis of the facial muscles, and prevents blinking or smiling on one side of the face.

So, Why Do I Care  While it is true that facial paralysis is not a deadly disorder (and only 0.5% of shingles patients develop it), but understanding how it comes about can be useful.  Because facial paralysis gives unusual changes to one’s facial expressions, the symptom is highly visible.  That highly visible nature makes facial paralysis an early warning sign of strokes or trauma to cranial nerves, disorders that are serious malfunctions of the our nervous system.

Plain English, Please!!!  First, let’s talk about what paralysis is. The loss of movement of body part or parts is defined as paralysis. Body parts are moved by muscles, and muscles must receive nerve signals, nerve impulses, to start moving.  Therefore, paralysis, the lack of muscle movement, or weak muscle movement, may be caused by malfunctioning of the muscles, or by the malfunctioning of the nervous system. Because the Herpes Zoster virus lives inside neurons, and not inside muscle cells, the Ramsay-Hunt syndrome is the result of the malfunctioning of the nervous system.

Second, let’s talk about how the Herpes Zoster virus affects the nervous system. In the type II Ramsay Hunt syndrome the reactivated virus multiplies in living neurons that make up cranial nerve VII. Those specific neurons are normally taking nerve impulses from the brain to the skeletal muscles that change our facial expressions to create smiling, blinking or frowning. The virus-infected neurons can not move the usual number of nerve impulses, and sometimes the virus kills the neurons making them unable to move any nerve impulses. This is condition is called neuropathy, a typical clinical finding in type II Ramsay Hunt syndrome.

Third, let’s talk about why neuropathy caused by Herpes Zoster infection leads to muscle weakness. Skeletal muscles of facial expression (like other skeletal muscles) remain relaxed until a nerve impulse tells them to contract. At the end of the neuron there is a bulging structure, the synaptic end bulb. That synaptic end bulb sits right on top of the skeletal muscle cells, just like your head would rest on a pillow. A nerve signal from the brain causes the release of acetylcholine, a type of neurotransmitter, just like your head on the pillow would start drawling. The released acetylcholine will instruct the skeletal muscle cell to contract. If the neuron is damaged, there are fewer nerve signals, less acetylcholine release, and less powerful muscle contraction. We perceive that as muscle weakening. Because the muscles of facial expression move the skin of our face to make us smile, blink, or frown, weakness of those muscles leads to a loss of those facial expressions, just like you see on the face of Justin Bieber.