Bell’s Palsy Fast Facts

Bell’s palsy is a neurological condition that causes paralysis or weakness in the muscles of the face.

The exact cause of Bell’s palsy is unknown, but it often follows viral infections. It may also be associated with other neurological disorders.

The condition is usually temporary, but symptoms can take months to resolve fully.

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The exact cause of Bell’s palsy is unknown, but it often follows viral infections.

What is Bell’s Palsy?

Bell’s palsy is a neurological condition that results in weakness or paralysis of facial muscles. The condition’s symptoms, which include drooping of facial features, usually come on quickly over two or three days and typically begin to improve within a few weeks.

In addition to weakness or paralysis, some people with Bell’s palsy also experience pain and changes in sensory perception.

Symptoms of Bell’s Palsy

Common symptoms of Bell’s palsy include:

  • Sudden onset of facial weakness or paralysis
  • Problems controlling facial muscles
  • Lopsided smile
  • Drooping eyelids or lips
  • Drooling
  • Excessive tear production
  • Increased sensitivity to sound in one ear
  • Loss of sense of taste
  • Pain in the jaw or behind the ear
  • Headache
  • Mild fever

What Causes Bell’s Palsy?

Scientists don’t know precisely what causes Bell’s palsy, but it is generally associated with inflammation or damage of the seventh cranial nerve, the nerve carrying signals between the brain and the face. The condition often occurs following a viral infection, suggesting that it could result from an inappropriate immune response in which the immune system mistakenly attacks healthy nerve cells.

Infections sometimes associated with Bell’s palsy include:

  • Cold sores
  • Genital herpes
  • Epstein-Barr virus
  • Cytomegalovirus
  • Adenovirus
  • German measles
  • Influenza
  • Mumps
  • Hand-foot-and-mouth disease

Facial paralysis is also sometimes associated with neurological disorders and other medical conditions, including:

  • Diabetes
  • High blood pressure
  • Lyme disease
  • Guillain-Barré syndrome
  • Sarcoidosis

People with certain risk factors are more likely to develop Bell’s palsy. Risk factors include:

  • Pregnancy
  • Obesity
  • Age (between the ages of 15 and 45)

Is Bell’s Palsy Hereditary?

Most cases of Bell’s palsy do not seem to be inherited. However, some cases seem to have a genetic component. In particular, rare instances in which the condition occurs more than once in the same person tend to run in families, suggesting that this type of Bell’s palsy may be inherited. However, scientists have not yet discovered a specific gene mutation that causes the condition.

How Is Bell’s Palsy Detected?

The early signs of Bell’s palsy may be similar to those of a potentially life-threatening stroke, making quick detection and medical intervention essential.

Early symptoms of Bell’s palsy may include:

  • Slight fever
  • Pain behind one ear
  • Weakness on one side of the face

How Is Bell’s Palsy Diagnosed?

Doctors may take several different diagnostic steps when suspecting a patient may have Bell’s palsy. Initial diagnostic procedures will focus on ruling out other possible causes of the symptoms, some of which may be life-threatening. Bell’s palsy symptoms may resemble those of a stroke, Lyme disease, acoustic neuroma, brain tumors, or other medical conditions.

Diagnostic procedures may include:

  • Electromyography (EMG). This test measures nerve function and may be able to detect problems with the cranial nerve.
  • Imaging. Imaging technologies such as magnetic resonance imaging (MRI) and computerized tomography (CT) are non-invasive ways to look at the brain, spinal cord, bones, and other parts of the body. Doctors can use these technologies to look for signs of damage to the cranial nerve.
  • Blood tests. Laboratory tests may be used to rule out other potential causes such as Lyme disease.  

Bell’s palsy may be diagnosed when no other medical condition or injury is found that would produce the condition’s symptoms.


How Is Bell’s Palsy Treated?

Most cases of Bell’s palsy do not require treatment, and symptoms resolve on their own within weeks. In more severe or prolonged cases, treatment approaches may include:

  • Corticosteroid medications
  • Antiviral medications
  • Pain relievers
  • Eye drops to prevent eye damage when the patient is unable to close one eye
  • Physical therapy

How Does Bell’s Palsy Progress?

Most people with Bell’s palsy recover fully and regain full use and control of their facial muscles. Recovery usually begins within weeks, and 80% of people fully recover within three months. However, in rare cases, some symptoms may persist for longer. A small number of people, especially those who experience complete facial paralysis, may have permanent impairments.

Possible long-term effects of Bell’s palsy include:

  • Involuntary contractions of some facial muscles during voluntary facial movements
  • Excessive tear production
  • Vision impairment in one eye

How Is Bell’s Palsy Prevented?

There is no known way to prevent Bell’s palsy.

Bell’s Palsy Caregiver Tips

Some people with Bell’s palsy also suffer from other brain and mental health-related issues, a condition called co-morbidity. Here are a few of the disorders sometimes associated with the condition:

Bell’s Palsy Brain Science

Bell’s palsy is caused by damage to the seventh cranial nerve, also known as the facial nerve. This nerve originates in a part of the brain stem called the pons and exits the skull through a small opening near the base of the ear. From there, the nerve divides into five main branches which connect to the various parts of the face. These branches are responsible for controlling muscles in the forehead, eyes, nose, lips, and chin and are essential for producing facial expressions.

In addition to controlling facial muscles, the facial nerve is also responsible for other functions, including the sense of taste, sensitivity to sound, and tear production.

Bell’s palsy occurs when an interruption of blood supply, or compression caused by swelling, results in damage to the facial nerve, usually at the point where it exits the skull. Symptoms may vary depending on the exact location of the nerve damage.

Bell’s Palsy Research

Title: Intratympanic Steroid for Bell’s Palsy

Stage: Recruiting

Principal investigator: Arnaldo Rivera, MD

University of Missouri

Columbia, MO

Facial nerve paralysis is due to inflammation surrounding the facial nerve. Current clinical practice guidelines for treating facial nerve paralysis recommend a 10-day course of oral steroids +/- oral acyclovir. Treatment should begin within 72 hours of symptom onset. In patients with complete facial paralysis, electrodiagnostic testing should be offered to the patient (1-2). In patients with 90% degeneration on electroneuronography (ENoG) testing, facial nerve decompression may be considered, but this is not a current recommendation.

In 1973, Bryant reported on ten cases where intratympanic steroid injection was used to treat Bell’s palsy (3). All but one of these patients had complete recovery of their facial nerve function. The remaining patient had a 75% recovery. None of these patients suffered complications from the injections. The next study published on intratympanic steroid injection for Bell’s palsy was not published until 2014 (4). It was a randomized control trial that divided patients into standard treatment (oral steroids and acyclovir) versus standard treatment with intratympanic steroid injection. There was not a statistically significant difference between the complete recovery rate of the control group and of the intratympanic steroid group; however, the time to recovery was significantly shorter in the intratympanic steroid injection group as compared to the control group. Limitations of this study include small sample size and a high attrition rate.

There have not been any other studies published in the literature looking at improving facial nerve recovery in idiopathic facial nerve paralysis with the use of intratympanic steroid injections.


Title: A Study of NTX-001 in the Treatment and Prevention of Facial Paralysis Requiring Surgical Repair

Stage: Not Yet Recruiting

Study Director: Seth Schulman, MD

Neuraptive Therapeutics Inc.

This study involves the use of an Investigational Product called NTX-001. It is a product used in the repair of nerve injuries. It is used in the operating room. The main purposes of this study are to 1) see how safe NTX-001 is when used in nerve repair and, 2) determine if the nerve becomes functional in a shorter period compared to what is typically done to treat nerve injuries.

Facial paralysis can be a consequence of traumatic facial nerve injury, iatrogenic causes, malignancy, congenital syndromes, and viral infections. Prolonged paralysis can result in ocular complications, articulation difficulties, impaired feeding, and difficulty in conveying emotion through expressive movement. The current treatment for permanent facial paralysis is facial reanimation surgery, which encompasses a broad range of procedures that restore form and function to the paralyzed face.

The importance of understanding the health utility of facial paralysis and the value of facial reanimation surgery increases. PEG-fusion is a promising therapy for patients that have, or will have, nerve conditions or injuries resulting in facial palsy that can be addressed surgically. Patients with clinical evidence of facial paralysis requiring facial nerve repair from conditions or interventions that have, or may result in, paralysis will be evaluated for participation. The primary objective is to assess the safety of NTX-001 across 12 months following the nerve repair. The study will measure improvement in Sunnybrook Facial Grading System (SB) for efficacy. Additionally, measures will include an EMG evaluation for assessment of nerve function intraoperatively, image-based automatic facial landmark analysis, improvement in Facial Clinimetric Evaluation Scale score, and Patient Global Impression of Change Response (PGIC).


Title: 3D Dynamic and Patient-Centered Outcomes of Facial Reanimation Surgery in Patients With Facial Paralysis

Stage: Recruiting

Principal investigator: Carroll Ann Trotman, BDS, MA, MS

Tufts University School of Dental Medicine

Boston, MA

In this study, patients who have undergone facial paralysis surgery will be asked to participate. The goal of this study is to compare the facial disability and perception outcomes of facial reanimation surgeries in patients with extensive and permanent unilateral paralysis using 3D analysis, and compare patient-centered outcomes of facial appearance, well-being, and satisfaction using validated questionnaires. The focus point of this study will be on outcomes of mid-facial reanimation surgeries in patients with more extensive and permanent, unilateral, paralysis of varied etiology and presentation.

The specific aims of the study are as follows.

Specific Aim 1. To quantitatively determine the surgical effects/impact on facial disability (facial impairment and disfigurement) among four surgically treated groups of patients with unilateral facial paralysis who undergo free gracilis muscle transfer driven by (1) a trigeminal nerve (nV) graft, (2) a crossface nerve graft (nVII), (3) dual innervation comprising both nerves, and (4) midfacial modification.

Researchers will compare the changes in facial disability among the groups before and after surgery, and the differences in facial disability between each surgery group and the controls before and after surgery.

Specific Aim 2. To compare among the surgery groups the changes in self-perceptions of facial appearance and well-being that occur due to facial reanimation surgery, and to compare the surgery groups before and at 18 months to historical controls recruited during the tenure of the R21 grant.

Specific Aim 3. In patients with facial paralysis, to compare surgeons’ current qualitative assessment and 2D, quantitative assessment of facial impairment and disfigurement with the objective, 3D, quantitative assessments to determine the clinical utility of the 3D assessment approach as an outcome measure and relevance for dissemination to the surgical community.

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