A 58 year old man comes to your ED with a chief complaint of facial drooping. He woke up from a nap and noticed the left side of his face was drooping. His father had a stroke in his late 60's, and he has high cholesterol. You see the patient in Figure 1. The triage nurse has asked you if they should activate the stroke team. What do you do?
The answer is no, do not activate the stroke team. While tPA is probably safe in Bell's Palsy, it is just bad form.
This gentleman has a Bell's Palsy, or a peripheral 7th cranial nerve palsy. The 7th cranial nerve, or facial nerve, is both a motor and sensory nerve. It supplies motor function to the muscles of facial expression, as well as the sensation of taste from the anterior 2/3 of the tongue. It also helps with lacrimation and salivation. There are many potential causes, including infectious (HSV, Lyme, CMV, EBV being common) as well as post URI and idiopathic.
History and Physical
The history and physical exam are all you need for diagnosis. Patients will usually report onset within 48 hours of a unilateral facial palsy that involves the forehead. They may also report hyperacusis and otalgia, as well as decreased lacrimation. Early on, almost 60% will report decreased or altered taste and aching of the affected side's ear (1). Pay careful attention to things that may indicate a cause (tick exposure, recent URI, facial rashes, etc).
On physical exam, you will be looking for the following:
- Flattened nasolabial fold
- Asymmetric smile (cannot initiate smile on affected side)
- Drooping of the affected eyelid. They will also be unable to fully close the affected eyelid, but will notice that the eye rolls upward with attempt to close the affected eye.
- Loss of or inability to wrinkle or move the affected side of the forehead: This is one of the most crucial components. The branch of the facial nerve innervating the forehead is actually innervated from both hemispheres of the brain, so a central 7th lesion would still have innervation to the forehead (want a deep dive on this? Check this out). In a peripheral 7th palsy, the entire nerve is knocked out, so you lose movement of the forehead. This is essentially the sine qua non of Bell's Palsy.
- Intact extra ocular movement: the nucleus of the 6th cranial nerve (abducens nerve) is relatively close to the 7th nucleus, and the 7th nerve courses around the nucleus of the 6th nerve. Theoretically, a very small stroke that affected this portion of the 7th nerve coursing around the 6th nucleus along with the 6th nucleus could mimic a Bell's Palsy, but you would expect to see the inability to abduct the eye on the affected side (Figure 2)
- Taste abnormalities: what, don't you carry around a sample of multiple different tastes in your ED Doctor bag...
- Decreased lacrimation
Diagnosis and Treatment
While a Bell's Palsy is a diagnosis of exclusion, you have excluded all other causes by performing the above exam. I have discussed this with a few neurologists. One in fact told me the following: "There are rare instances in which an infarct can yield a peripheral-appearing facial deficit but these are case report zebras." Works for me. CT imaging will not be helpful in the patient with the correct history and physical exam. In complicated patients, such as those with known metastatic disease, multiple sclerosis, or systemic lupus, MRI may be helpful. Occasionally mass lesions can cause a Bell's, however ED MRI is not required and can be performed in routine follow up. However, for uncomplicated facial nerve palsy, no advanced imaging is needed.
In regards to treatment, perhaps the most important thing you can do is advise taping the eyelid at night and providing lubricant drops or ointment for the eye, as prolonged opening leads to drying, corneal abrasions and ulcers. For style points, if you are going to tape the eyelid, you should put a piece of gauze over the closed eye before taping to avoid ripping out eyelashes when you remove the tape. There is level I evidence that steroids are indicated, especially early in the course (within 72 hours), and improve long term recovery of facial nerve function. They do state, however, that in patients who have diabetes or other contraindications to steroids, it is ok to omit this (especially if later in the course). Generally, the studies indicate 1 mg/kg of prednisone per day (up to 80 mg) for 7-14 days. You should be tapering during the second week if you are treating for more than a week (3). Antivirals have not been shown to increase functional outcomes and are not routinely recommended for uncomplicated cases (2, 4).
So what if you do pull the trigger, and the patient goes down the stroke path? Let's say in your zeal to meet your deadlines, you give this person tPA? Well, one study showed that patients who were treated with stroke mimics actually did pretty well, so it is likely no harm no foul (5). However, try to avoid this at ALL costs, as tPA is expensive, risky, and of course does nothing to treat the condition.
The Bottom Line
Patients with the correct history and physical exam do not need imaging for an uncomplicated facial nerve palsy. Treatment should be focused on steroids if no contraindications exist, and protecting the affected eye with lubricant drops or ointment as well as nighttime taping. Do not add antivirals in uncomplicated cases.
Are you still worried you're going to miss a bleed or a stroke?
Well, a recent study published in Annals of EM says that you should not be. Turns out we are pretty good at diagnosing Bell's. In this retrospective study, out of almost 44,000 patients, only 0.8% were diagnosed with an alternate condition (39.9% of which were found within a week), with only 0.3% of these being intracranial processes (6).