Bell’s Palsy or Stroke?

Bell’s Palsy or Stroke? A Medical Student Clinical Pearl

Alicia Synette, Med III

Class of 2022 MUN

Reviewed by Dr. Jeremy Gross

Copyedited by Dr. Mandy Peach


A 48M presented to the Emergency Department with right sided facial droop and altered facial sensation for two days.

He woke up one morning and described the right side of his face as feeling “saggy”. At this time, he assumed that he had slept funny. The facial droop progressed that day until it became noticeable by his wife. Two days later, he decided to go to the ER when his symptoms did not resolve. At this time, he described altered sensation at the right side of the face and tongue, which he compared to the feeling of local anesthetic after dental work. His smile was “crooked”, he was unable to purse his lips, and he could not completely close his right eye. The affected eye was also red and irritated. Taste and hearing were unchanged. Review of systems was otherwise unremarkable.

PMH: T2DM, HTN, hyperlipidemia

Medications: Ramipril, Fenofibrate, Janumet, Rosuvastatin, ASA, Lantus, Humalog

On exam, he appeared well, he was afebrile, and vital signs were stable. Pupils were equal and reactive to light. Conjunctival injection was present at the right eye with increased tearing. Mild facial droop was apparent. The right eyelid was droopy and he was unable to keep it closed against resistance. Facial movements on the right side were also weak (smile, purse lips, puff cheeks, close eyes tight), however, weakness of the forehead muscles could not be appreciated when asked to raise his eyebrows. Sensation to light touch was altered at V1. Pinprick touch was normal. There was no deviation of the tongue. He had 5/5 strength and normal sensation bilaterally at the extremities. Normal rapid alternating movements and normal heel to shin test. Normal hearing bilaterally and no hyperacusis.

Accessed from grepmed –

Differential Diagnosis for Facial Nerve Palsy

Table 1: differential diagnosis for facial nerve palsy.6


Lab results were unremarkable aside from an elevated random blood glucose. HbA1C level from one month prior to the ER visit was 11.1%.

CBC – LKC 8.2, Hgb 137, PLT 213

Electrolytes – Na 140, K 3.9, Cl 103

Glucose (random) 9.9

Urea 5.4, Ca+ 2.45, Mg 0.87, TSH 1.33

CT head showed no evidence of mass lesion, hemorrhage, hydrocephalus, subacute or chronic infarct.


Bell’s Palsy

Bell’s palsy is an isolated CNVII (facial nerve) paresis/paralysis as a result of acute inflammation and/or edema of the nerve. The onset is typically acute and progresses within hours, and while the cause is unknown, it is thought that the most likely etiology is viral (HSV, CMV, EBV).5


The facial nerve innervates the facial muscles, therefore, CNVII palsy presents with sudden onset unilateral facial paralysis, which can include: 1

  • Eyebrow sagging.
  • Inability to close the eye.
  • Disappearance of the nasolabial fold.
  • Drooping at the affected corner of the mouth, which is drawn to the unaffected side.2


CNVII also innervates the lacrimal glands, salivary glands, stapedius muscle, and taste fibres on the tongue, therefore, other associated features can include:1

  • Decreased tearing.
  • Hyperacusis
  • Loss of taste sensation on the anterior 2/3 of the tongue. 2

Figure 1: Anatomy of the facial nerve. 6


Risk Factors5

  • Pregnancy
  • Severe pre-eclampsia
  • Obesity
  • Hypertension
  • Diabetes
  • Upper respiratory illnesses

House-Brackmann Classification

The House-Brackmann classification seen below is used to determine severity of facial nerve dysfunction and has prognostic value. The lower the grade, the more likely a patient is to make a full recovery.7

Table 2: House-Brackmann classification of facial nerve dysfunction.3



Diagnosis of Bell’s Palsy is considered a clinical diagnosis so there is no gold standard test, however, other causes of facial nerve palsies tend to have associated features and can be ruled out clinically. Most significantly, it is important to rule out life-threatening central lesions, such as ischemic/hemorrhagic stroke.4

Central vs. Peripheral Lesions

Central lesions – result in forehead sparing, as the facial nerve is innervated by ipsilateral and contralateral fibres from the motor cortex. Patients with forehead sparing need a head CT to rule out a central cause such as a stroke or mass!5

Peripheral lesions – the lesion is below the nucleus, and all the fibres innervating the facial nerve will be affected. Results in no forehead sparing.5

Figure 2: facial nerve lesion vs. supranuclear lesion with forehead sparing. 6

Other pertinent findings on history can include: rashes, arthralgias, or fevers, exposure to ticks (Lyme disease), and vesicular eruption (Ramsay Hunt Syndrome). In addition to a full cranial nerve and peripheral nerve exam, physical examination should involve assessment of the ear, tympanic membrane, and parotid gland for signs of AOM, cholesteatoma, or parotid tumor.6

Further investigations6

  • Lyme serology: if clinical suspicion for Lyme disease
  • Head CT: gradual onset of symptoms or forehead sparing
  • Neurology referral: bilateral palsies or no improvement



Corticosteroids +/- antiviral is the choice of treatment for Bell’s Palsy. Studies have demonstrated that antivirals alone have no benefit, but in combination with corticosteroids there is a significantly increased benefit compared to corticosteroids alone. Patients should be started on corticosteroids within 72 hours of presentation for a course of at least 7 days. Physicians can also discuss with patients the potential benefit of adding an anti-viral.8

Eye care is an important consideration in these patients as a proportion will have incomplete eye closure, putting them at risk of corneal injury. Artificial tears during the day are recommended as well as taping the eyelid closed to prevent excessive dryness or trauma.9

With treatment, patients will see improvement within weeks and most experience full recovery within 3-4 months. 5


Case Conclusion

Our patient was started on valacyclovir 100mg TID x7 days and prednisone 60mg daily x 7 days for suspected Bell’s Palsy. Despite a normal CT, which helped to rule out central causes of facial paresis (stroke, subdural hematoma, brain tumor), the potential forehead sparing of the patient’s presentation presented concern for stroke. He was referred to Stroke Prevention Clinic and was seen the following day.

Neurology assessed the patient and appreciated that there was mild weakness in the forehead noted as a “reduction of wrinkles”, therefore, the diagnosis of Bell’s Palsy was confirmed. It was recommended that he continue the valacyclovir and prednisone course. It was also recommended that he patch the eye in the evenings and continue to use lubricating eye drops in the affected eye to prevent exposure keratitis.

Key Points

  1. Bell’s palsy results in unilateral facial nerve paresis/paralysis, without forehead sparing
  2. Associated symptoms may include: decreased tearing, hyperacusis, loss of taste
  3. No investigations are required; however, patients with true forehead sparing need a head CT as this finding is suggestive of a central lesion
  4. Patients with systemic symptoms, gradual onset, or bilateral symptoms should have further work-up
  5. Most cases will resolve in 3-4 months with treatment
  6. Treatment with corticosteroids +/- an antiviral for 7 days should be initiated within 72 hours of symptom onset




  1. Baugh, R., et al. 2013. Clinical Practice Guideline. Otolaryngology–Head and Neck Surgery, 149(3_suppl), pp.S1-S27. Retrieved from:
  2. 2021. CRACKCast E105 – Brain and Cranial Nerve Disorders – CanadiEM. Retrieved from:
  3. House, J. and Brackmann, D., 1985. Facial Nerve Grading System. Otolaryngology–Head and Neck Surgery, 93(2), pp.146-147. Retrieved from:
  4. McCaul, J., Cascarini, L., Godden, D., Coombes, D., Brennan, P. and Kerawala, C., 2014. Evidence based management of Bell’s palsy. British Journal of Oral and Maxillofacial Surgery, 52(5), pp.387-391. Retrieved from:
  5. 2021. RACGP – A general practice approach to Bell’s palsy. Retrieved from:
  6. Tiemstra JD, Khatkhate N. Bell’s palsy: diagnosis and management. Am Fam Physician. 2007 Oct 1;76(7):997-1002. PMID: 17956069. Retrieved from:
  7. Yoo, M., et al. 2020. Evaluation of Factors Associated With Favorable Outcomes in Adults With Bell Palsy. JAMA Otolaryngology–Head & Neck Surgery, 146(3), p.256. Retrieved from:
  8. Hato, N., et al. Efficacy of early treatment of Bell’s palsy with oral acyclovir and prednisolone. Otol Neurotol. 2003 Nov;24(6):948-51. Retrieved from:
  9. Ronthal, M. Greenstein, P. 2021. Bell’s palsy: Treatment and prognosis in adults. Retrieved from Uptodate October 26, 2021 from






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