Palsy means paralysis. Bell’s Palsy (named after a Dr. Bell from the early 1800’s) is when one side of the face becomes partially- or fully-paralyzed. It’s due to a problem with the Facial Nerve, the 7th of our 12 Cranial Nerves which begin in the brain and control movement and/or sensation of the head and neck.
The term Bell’s Palsy is well-known, but it technically means that we don’t know why it happens. Yet nowadays, it seems that up to 70% of cases are due to Herpes simplex virus (HSV; see below). So we more properly say “Facial” or “7th Nerve” Palsy instead, although most people still call it “Bell’s”.
It’s easy to identify a Facial Nerve Palsy on physical exam. A patient:
- can’t raise their eyebrow well (or at all)
- can’t close their eye completely
- we see the eyeball turn upward as they try to squeeze it shut
- can’t grimace / smile / frown well
- has a droopy face
Facial Palsy is usually due to inflammation within a tiny opening in the bone right in front of the ear, where the nerve which has already exited the brain finally reaches the face. It’s more common among persons with Diabetes, and pregnant women. But before we ascribe it to HSV, we run through a number of other possibilities:
** Herpes Zoster (Shingles) — Reactivation of the Varicella (chickenpox) virus, which has remained dormant in a nerve but awakens years later. We suspect this if along with the palsy, there’s also ear or facial pain, ringing in the ear, or vertigo.
** Lyme Disease — We suspect this in high-risk areas during high-risk seasons (see link). We’d especially suspect Lyme in children with Facial Palsy, since they otherwise get the symptom so rarely. In areas with lots of Lyme Disease, clinicians treat for it whenever a child has “Bell’s Palsy.”
** Acute (Primary) HIV — This refers to symptoms during the very first month after being infected with HIV. We’d do various tests for the virus if a patient with Facial Palsy might have been at high risk, especially if they also have a fever, or have the palsy on both sides. See the link.
** Ear Tumors / Infections — Very rare causes. We’d be able to feel something right at the opening to the ear canal, or see an infection looking inside.
** Stroke — As noted, Facial Palsy is from compression of the 7th Cranial Nerve after it has left the brain. We tell patients, “It’s not a Stroke.” But in rare cases, a stroke in the brain itself can be responsible, and there’s a way to tell. When Stroke is the cause, the eyebrow isn’t affected, only the lower face. We have a patient raise their eyebrows, & we count the wrinkles on each side. Fewer wrinkles on the affected side means eyebrow weakness, so no stroke. See the pictures below.
Not a Stroke: entire half of face is weak (woman’s left side, man’s right side)
Stroke: able to raise both eyebrows fully, but lower left half of face weak when smiles
If none of the above conditions seem likely, we diagnose idiopathic Facial Palsy, i.e. “Bell’s.” Idiopathic is a fancy medical term for “just happens on its own, don’t know why.” But since the 1980’s, we’ve learned that 70% of cases seem due to Herpes simplex virus, Type-1 (HSV-1). That’s the type we get as children, and which causes cold sores / fever blisters on the lip; not the STD (type-2). HSV-1 is transmitted to the mouth or nose by saliva (microscopic drops); initial symptoms (if any) disappear on their own, but the virus never goes away. It remains latent (dormant) in a nerve, but can reactivate later in life.
Without treatment, 85% of patients with Facial Palsy begin to recover within 3 weeks, and achieve full or almost-complete recovery within 6 – 12 months. Those with more severe weakness at the beginning may have some permanent weakness. The most important part of treatment is high-dose steroid medication (e.g. prednisone) for 10 days; anti-Herpes medicine (at high doses, as given for Herpes Zoster) may also help, but isn’t as important.
Treatment should be begun as soon as possible. Another important component is having the patient tape their eyelid shut, certainly during the night, and the day too if they’re willing. Since the eyelid doesn’t close completely, the cornea can be injured from dryness. The patient should tape a small gauze pad over the lid, to maintain just the very tiniest bit of pressure (the purpose isn’t to keep light out, but to keep the lid closed).