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A Case of Post-traumatic Delayed Facial Nerve Palsy in a Child

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A Case of Post-traumatic Delayed Facial Nerve Palsy in a Child – A Medical Student Clinical Pearl

Jacqueline Mincer, BSc, MSc

Dalhousie Medicine New Brunswick Class of 2022, Med III

Reviewed by: Dr. Erin Slaunwhite

Copyedited by: Dr. Mandy Peach

History of Presenting Illness:

A 10-year-old girl presented to the emergency department (ED) one week after a bike accident with left-sided hemifacial palsy. The patient was biking down a hill without a helmet when she fell onto her left side. Emergency medical services (EMS) brought the patient to the ED with a Glasgow Coma Scale (GCS) score of 15. The patient denied loss of consciousness, nausea, vomiting or headache. Small amounts of blood were noted around her left tragus; however, the patient denied any hearing impairments at the time. She was otherwise healthy with no prior surgeries, no allergies, and no medications.

 

CT head, CT cervical spine, and shoulder XR were ordered. Imaging revealed a transverse fracture through the distal third of the clavicle with 100% displacement (Figure 1). CT head and cervical spine were both reported as normal, with no significant post-traumatic abnormalities detected.

Figure 1: L clavicle fracture

The clavicle fracture was treated non-operatively. The patient was discharged home with a sling to immobilize the shoulder and was provided with an outpatient follow-up appointment with orthopedics.

 

Four days after the accident, left-sided facial changes were first noticed and had been progressively worsening. The patient complained of left-sided numbness, photosensitivity, difficulty blinking, and lip palsy (Figures 2a, 2b). There was ongoing bloody drainage and intermittent hearing difficulties from the left ear.

Figure 2: L sided facial nerve palsy*:

2a) incomplete closure of the left eye

2b) limited ability to open mouth/smile on the left side; decreased movement of the upper left eyebrow

*photos taken with consent of patient and parent

ANATOMY REVIEW:

To build a complete differential diagnosis, let’s first review the anatomy of the facial nerve as it enters and exits the skull:

  • The facial nerve is the 7th paired cranial nerve.
  • It arises in the pons and travels through the temporal bone via the internal acoustic meatus then travels through the “Z” shaped facial canal exiting the skull via the stylomastoid foramen (Figure 5).
  • Upon exiting the skull, the facial nerve runs anteriorly to the outer ear and gives rise to the posterior auricular nerve branch. The main motor root of the facial nerve passes through the parotid gland, ultimately splitting into 5 terminal branches: the temporal, zygomatic, buccal, marginal mandibular and cervical branches (Figure 6).

Figure 5: Pathway of facial nerve through skull. 

Dalhousie Medicine neuroanatomy lab manual.

Figure 6. Branches of the facial nerve (VII)

The facial nerve is a mixed nerve, containing motor, sensory and parasympathetic fibers.(1)

  • Motor: innervates muscles of facial expression.
  • Sensory: taste sensation from anterior 2/3 of the tongue (via chorda tympani, a branch of the mandibular nerve, V3).
  • Parasympathetic: supplies glands of the head and neck
    • Lacrimal gland (tearing), sublingual and submandibular glands (salivary).

 

IMPORTANT FEATURES ON HISTORY AND PHSYICAL EXAM:

History:

  • Onset and progression (gradual onset more suggestive of mass lesion)
  • Recent rashes, arthralgias, fevers or other illnesses
  • Tick exposure, recent trauma, or prior history of peripheral nerve palsy

 

Exam:

  • Head & Neck: inspect external ear, ear canal, tympanic membrane, oropharynx. Palpate parotid gland.
  • Neurologic exam: cranial nerve exam (Figure 8) and full neuro exam. Differentiate between upper motor neuron and lower motor neuron lesions by assessing forehead involvement. Forehead paralysis on affected side is suggestive of a lower motor neuron (peripheral) lesion. While no forehead paralysis on the affected side is suggestive of an upper motor neuron (central) lesion. This is due to bilateral innervation of the forehead from the central nervous system.
  • Skin: inspect for lesions suggestive of herpes zoster, Lyme disease or dysmorphic features

https://www.reviewofoptometry.com/article/the-neurologic-exam-stepbystep

Figure 8: Cranial nerve function and testing

DIFFERENTIAL DIAGNOSIS:

Pediatric facial nerve palsy can be congenital, acquired, or idiopathic.

 

Congenital: secondary to delivery trauma, genetic causes, or may make up one feature of a broader syndromic malformation.(2)

Acquired: resulting from infection or damage/trauma to nearby structures.

  • Infectious pathogens include Borrelia Burgdorferi, Herpes Varicella-Zoster (most common), Epstein-Barr virus, Haemophilus influenza, Tuberculosis, CMV, Adenovirus, Rubella, Mumps, Mycoplasma pneumoniae, and HIV.
  • Disease to neighbouring structures (Figure 7) include Otitis media, Cholesteatoma, Mastoiditis, and Meningitis.

 

https://www.statpearls.com/ArticleLibrary/viewarticle/49275

Figure 7: neighbouring structures to facial nerve

  • Trauma/injury to the facial nerve from temporal bone fractures (at the basilar level)
  • Iatrogenic paralysis (surgical complication) from procedures involving the parotid gland, middle ear or mastoid.

Less common, acquired etiologies:

  • Inflammatory: vasculitis, HSP, or Kawasaki disease.
  • Neoplasm: schwannoma, hemangioma, bone tumor (rhabdomyosarcoma, histiocytosis), leukemia, parotid gland tumors.

Idiopathic: In approximately 50% of cases, the etiology remains unknown. Idiopathic facial paralysis is commonly referred to as “Bell’s Palsy”

 

INVESTIGATIONS, PROGNOSIS, TREATMENT:

Investigations, prognosis and treatment are all highly dependent on the overall clinical picture, including underlying etiology and severity of palsy.(3)

 

Investigations:

  • Imaging is warranted in patients who present with atypical signs, such as involvement of neighbouring cranial nerves, chronic otitis media, acute mastoiditis, temporal bone trauma, suspected malignancy, slow onset (>3 weeks), or no improvement at 6 months.
  • In “typical” incomplete facial palsy with good recovery, imaging may not be necessary.
  • Consider serologic testing to rule out Lyme disease if warranted.
  • Consider EEG, neuroimaging, lumbar puncture based on history and physical exam. (3)

 

Prognosis:

  • Prognosis will vary depending on cause and mechanism of injury.
  • Most children with Bell’s palsy recover well and regain most if not all of their function. (3)

 

Treatment:

  • If applicable, treat the underlying disorder (e.g. Lyme disease, acute otitis media).
  • Bell’s Palsy:
    • Early treatment (within 3 days of symptom onset) with oral glucocorticoids. (2)
    • Prednisone 1-2mg/kg daily (up to 60-80mg) x 5 days, then a five-day taper by 10mg per day. (3)
  • Congenital or permanent acquired facial palsy: consider surgical consult
  • All patients will require supportive care:
    • Artificial tears to protect the cornea of the affected eye.
    • Taping of the eyelid shut overnight in patients unable to completely close the eye.

 

Case Conclusion:

The ED physician consulted the on-call radiologist and neurosurgeon. The CT-head from the day of the accident was revisited, detecting a 4cm basilar skull fracture to the left temporal bone (Figure 10).

Figure 10: Basal skull fracture

Delayed hearing loss and bloody drainage from the left ear was suggestive of a trauma-induced tympanic membrane perforation.

Inflammation from the basilar skull fracture and/or ruptured tympanic membrane likely explains compression of the facial nerve. In this case, the delayed presentation of left-sided facial palsy is a reassuring prognosis. It points towards inflammatory compression of the nerve as opposed to complete laceration of the nerve at the time of trauma.

She was discharged home with a two-day prescription for Dexamethasone 10mg PO once daily. A plan was made for a repeat CT head in 6-8 weeks as well as outpatient follow up with orthopedic surgery, neurosurgery, and pediatric neurology.

Take Home Points:

o Facial nerve palsy in children can be classified as congenital, acquired or idiopathic in nature.
o The case presented here was an acquired facial nerve palsy, following a traumatic basilar skull fracture.
o Investigations, prognosis and treatment are highly dependent on underlying etiology and severity
o If known, it is important to treat the underlying etiology.
o Consider glucocorticoids at early onset (within 3 days of presentation) as well as supportive management (artificial tears, eyelid taping).

References:
1. The Facial Nerve (CN VII) – Course – Functions – TeachMeAnatomy [Internet]. [cited 2021 Jun 14]. Available from: https://teachmeanatomy.info/head/cranial-nerves/facial-nerve/
2. Ciorba A, Corazzi V, Conz V, Bianchini C, Aimoni C. Facial nerve paralysis in children. World J Clin Cases. 2015 Dec 16;3(12):973–9.
3. Facial nerve palsy in children – UpToDate [Internet]. [cited 2021 Jun 14]. Available from: https://www.uptodate.com/contents/facial-nerve-palsy-in-children?search=-%09Facial%20nerve%20grading%20(House-Brackman&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1#H4519763

 

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