What are the common causes of infranuclear facial nerve paralysis? How do you manage a case of traumatic facial nerve injury?

The following are the common causes of infranuclear facial nerve paralysis:

1. Bell’s palsy (most common)
2. Diabetes Mellitus
3. Post traumatic:
   • Birth injury
   • Temporal bone: Transverse(40-50%), Longitudinal (20%)
   • Iatrogenic: Mastoid surgeries- most commonly in 2nd genu (Pyramidal) and vertical segment
4. Infection:
   • Acute Otitis Media
   • Chronic Otitis Media
   • Ramsay Hunt syndrome
   • Lyme disease
5. Middle ear/Inner ear pathology:
   • Otitis media
   • Cholesteatoma
   • Vestibular Schwannoma
6. CNS pathology: stroke, Multiple sclerosis, Sarcoidosis, Brainstem tumour
7. Spinal Cord Pathology: GB syndrome

Diagnosis of facial nerve paralysis:

Thorough History:

• Onset →Immediate : nerve disruption/severe compression , Delayed : Nerve Oedema from trauma/viral reactivation
• complete/incomplete
• sudden/progressive
• co-morbities
• Risk factors
• Duration of symptoms
• Associated symptoms

Physical examination and grading the facial nerve paralysis is to be done

• General
• as warranted by symptomatology: Head/Neck/Otological and av
• House Brackmann system grading

Laboratory management as warranted(not for traumatic)

• CBC (infection or anaemia)
• ESR(vasculitis)
• Blood chemistry(DM)
• HIV TEST
• FTA  test(Syphilis)
• Lumbar Puncture (CSF examination) Lyme disease/MS/GBS

Audiometry:

• PTA
• Speech audiometry
• Tympanometry
• U/L SNHL on the side of paralysis; tumours in Internal Acoustic Canal/ Crebello-Pontine Angle

Imaging studies: Determination of site of injury

No return of facial function noted c/in 6 months tumour

• High Resolution  CT
• Gadolium-MRI

MANAGEMENT OF A CASE OF TRAUMATIC FACIAL NERVE INJURY

• Facial palsy is commonly seen in transverse fractures of temporal bones or iatrogenic trauma during middle ear surgery.
• Injury to facial nerve in skull fracture is rather uncommon in pediatric age group patients. This has been attributed to the increased flexibility of pediatric skull whereas iatrogenic is common because of anatomical variation in children.
• The timing of onset of facial palsy has an important bearing on its outcome. Immediate palsy invariably indicates total transection of the nerve, while delayed palsy indicates the development of neuronal oedema / hematoma with nerve compression inside a non expanding facial nerve bony canal. In any case it is really worthwhile to open up the mastoid in all cases of traumatic facial nerve palsy in order to have a look.
•  In the early stage of facial nerve palsy following injury, facial nerve decompression may be carried out to relieve the squeezing or pressure on the nerve but observation itself can help in many cases as the pressure on the nerve will recover by itself after the oedema is reduced.
• The treatment options available in the later stages following injury include Facial rehabilitation involving a wide range of treatment options including physiotherapy and speech and language therapy.Surgery options may include:-Facial nerve decompression – occasionally performed early on to relieve pressure on the nerve to allow it to work better.
  -Oculoplastic surgeries – a set of procedures in the eye region designed to protect eye function, improve symptoms of dryness and tearing and also overall appearance.
  -Smile surgeries – operations designed to restore symmetry at rest or even to create a smile movement on the affected side.
  -Rejuvenating procedures – One of the consequences of having a facial paralysis is that the tissues of the face tend to droop more.-Various procedures can help reverse that effect and improve symmetry. These include: brow-lift, face-lift, mid-face lift, fat grafting.

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