Bell’s Palsy & Trigeminal Neuralgia
Bell’s palsy (CN VII, idiopathic facial palsy) Verified · Sep 2026Bell’s palsy is sudden, usually one-sided weakness or paralysis of the facial muscles caused by dysfunction of the seventh cranial (facial) nerve; trigeminal neuralgia is a chronic pain disorder of the fifth cranial (trigeminal) nerve causing sudden attacks of severe, shock-like facial pain.
CN VII moves the face; CN V feels it. A new facial droop is a stroke until proven otherwise; Bell’s palsy takes in the whole half-face including the forehead, steroids work best within 72 hours, and the eye that cannot close must be protected. Trigeminal neuralgia fires on washing, eating, brushing teeth or a breeze; carbamazepine is first-line — not a PRN painkiller — and carries boxed skin and blood warnings.
What’s going wrong in the body
The normal physiology, where it fails, and why the body’s compensation backfires.
01 Two nerves: CN VII moves the face, CN V feels it
[Bell’s palsy] "Bell’s palsy results from a problem in the seventh cranial nerve, also called the facial nerve, which connects the brain to the muscles that control facial expression. The seventh cranial nerve also affects taste and ear sensation." It also "innervates the stapedius muscle of the middle ear, and regulates the secretion of tears and nasal mucus."
[Trigeminal neuralgia] "It affects the trigeminal nerve, or the fifth cranial nerve, which provides feeling and nerve signaling to parts of the head and face." Its three branches — ophthalmic, maxillary and mandibular — supply forehead, cheek and upper jaw, and lower jaw; "the maxillary or mandibular branches are the most commonly affected."
So the contrast is movement versus sensation: Bell’s palsy weakens facial expression (and can change taste, tearing and sound tolerance); trigeminal neuralgia leaves movement intact but produces pain.
02 Bell’s palsy — a swollen nerve in a narrow bony canal
[Bell’s palsy] It "results from inflammation of the facial nerve, typically originating in the labyrinthine segment" — the narrowest part of its bony canal, "with an average diameter of 0.7 mm." "There is a hypothesis that edema of the nerve within the Fallopian canal compromises perfusion, leading to nerve dysfunction." The trigger is uncertain: StatPearls says "there is evidence to suggest that Human herpesvirus 1 is responsible for most of the cases," while NINDS says "The exact cause of Bell’s palsy is unknown," listing possible triggers such as "An existing (dormant) viral infection" and "Impaired immunity due to stress, sleep deprivation, physical trauma, minor illness, or autoimmune syndromes."
The whole half-face, including the forehead. Because the lesion is in the nerve itself, "all branches of the facial nerve are roughly equally impaired on the affected side of the face." By contrast, "a cortical stroke will typically leave forehead movement intact on the affected side" — but "a brainstem stroke will cause hemifacial weakness that does not preserve forehead movement." So forehead involvement does not rule out stroke.
Recovery and misdirected regrowth. Mild injury is only a conduction block; worse injury lets regrowing axons go astray — "discoordinated movements and spasms (synkinesis)" and "aberrant reinnervation of the lacrimal gland leads to tearing that accompanies salivation."
03 Trigeminal neuralgia — a pulsing vessel wears the nerve’s insulation
[Trigeminal neuralgia] "Most cases of trigeminal neuralgia are secondary to compression of the trigeminal nerve root within a few millimeters of its entry into the pons." "In 80% to 90% of these cases, the nerve root is compressed by an adjacent artery or a vein." Compression causes "subsequent nerve demyelination in the area of compression."
Why a light touch hurts (hypothesis). Demyelinated fibers may short-circuit: "The ephaptic link between fibers involved in pain generation and fibers mediating light touch could account for the precipitation of shock-like pains in the facial trigger zone by light tactile stimulation." StatPearls keeps the hedge: "How demyelination leads to the symptoms of trigeminal neuralgia is unknown."
Secondary TN. "In these cases, TN is caused by another disorder (such as multiple sclerosis, a tumor, or arteriovenous malformation" … "Individuals with secondary TN are more likely to be younger and to have pain on both sides of the face." "The development of trigeminal neuralgia in a young person should raise suspicion of multiple sclerosis."
Causes & risk factors
Modifiable factors are teaching targets — the patient can act on them.
Signs & symptoms
Each finding tied to the mechanism that produces it — and the triage it calls for.
Diagnostics
Complications
Medications for this condition
Why each class is prescribed here — every card links to its full pharmacology page.
[Bell’s palsy] First-line — early. NINDS: "oral steroids should be started within three days of symptom onset to reduce inflammation and swelling and increase the chance of recovering facial nerve function." NHS: "a 10-day course of steroid medicine." Monitor glucose in diabetes — antihyperglycemics are "added or adjusted as necessary." Not for Lyme or Guillain-Barré facial palsy ("steroids should be avoided").
[Bell’s palsy] Adjunct only. "Sometimes antiviral medications may also be prescribed to help increase the chance of recovering facial function," always with a steroid; StatPearls: most cases improve "with early corticosteroid therapy, with antivirals considered in select cases." Ramsay Hunt syndrome needs a higher antiviral dose and longer steroid course.
[Trigeminal neuralgia] First-line — carbamazepine. NHS: carbamazepine "is the first treatment usually recommended to treat trigeminal neuralgia"; "only carbamazepine is approved by the United States Food and Drug Administration (FDA) for treating trigeminal neuralgia." It "needs to be taken several times a day to be effective" — "Neither medication provides immediate relief"; the label: "This drug is not a simple analgesic." Stop "slowly, over days or weeks." Oxcarbazepine is an alternative with fewer interactions; "Both medications can cause hyponatremia." Carbamazepine reduces hormonal contraceptive effect ("Alternative or back-up methods of contraception should be considered"), "can cause fetal harm," and causes drowsiness — caution with alcohol and driving.
[Trigeminal neuralgia] Baclofen — "shown to decrease the intensity and severity of attacks in 74% of patients" (StatPearls); an add-on or alternative.
[Trigeminal neuralgia] Clonazepam is among second-line agents, though "comprehensive efficacy data is lacking."
[Bell’s palsy] Pain relief — NINDS: "aspirin, acetaminophen, or ibuprofen," checking interactions first. [Trigeminal neuralgia] Not usually helpful — "Common pain-relieving medications (such as aspirin and ibuprofen)" and opioids "are not usually helpful in treating TN."
[Bell’s palsy] Pain relief (NINDS). [Trigeminal neuralgia] NHS: failure of standard painkillers such as paracetamol is a reason to see a GP.
[Trigeminal neuralgia] Not usually helpful — "opioid medications such as hydrocodone are not usually helpful in treating TN."
Beyond medications
- [Bell’s palsy] Eye protection — the key early intervention. "the most important early intervention for most patients is corneal protection in the event that eye closure is impaired; this consists of artificial tears, eyelid taping, and potentially upper eyelid weight placement." Tears through the day, lubricant ointment at night; NHS: "surgical tape to keep the eye closed at bedtime"; NINDS: eye drops "or eye patches" especially while sleeping. "Upper eyelid stretching 2 to 3 times per day is also very helpful."
- [Bell’s palsy] High-risk eyes — corneal anesthesia, absent Bell phenomenon, slow recovery or an only-seeing eye may need a scleral contact lens or an upper-eyelid weight.
- [Bell’s palsy] Physiotherapy and other therapy — NINDS: "Physical therapy, facial massage, or acupuncture may help"; StatPearls calls acupuncture’s benefit questionable. Synkinesis is treated with "physiotherapy, botulinum toxin injections, and potential surgical interventions." Decompression surgery remains controversial.
- [Trigeminal neuralgia] Surgery — microvascular decompression is "the most effective at preventing pain long-term" and "the goal is not to produce numbness"; it carries risks such as hearing loss and, rarely, stroke. Rhizotomy always causes "some degree of sensory loss and facial numbness"; radiosurgery relief "may take over a month to develop." Rhizotomy can leave "corneal numbness"; eye-care measures "may also be appropriate" for a numb cornea.
Nursing considerations
The RN-specific layer — each action paired with the reason it matters.
How a real nurse thinks
The clinical-judgment loop, worked for a typical presentation — reasoning, not reference.
- 1 Recognize cues
A new one-sided facial droop involving the forehead, with incomplete eye closure and an ache behind the ear, in a pregnant woman, about 8 hours from onset.
- 2 Analyze cues
The whole half-face pattern fits Bell’s palsy, and pregnancy is a risk factor — but a brainstem stroke also involves the forehead, and NHS treats a one-sided droop as a possible stroke. Stroke must be excluded first. If it is Bell’s palsy, steroids work best within 72 hours and the eye is at risk.
- 3 Prioritize
Stroke assessment first, then early steroids and eye protection.
- 4 Generate solutions
Notify the provider now for urgent stroke evaluation; once stroke is excluded, expect a steroid (with glucose monitoring) and teach tears by day, ointment and taping at night, and to report eye pain or light sensitivity immediately.
- 5 Take action
SBAR: 34-year-old, 30 weeks pregnant, right facial weakness including forehead, onset about 8 hours ago, incomplete right eye closure, no limb weakness. Requesting urgent assessment to exclude stroke; eye protection started. The provider examines her, finds no other deficits and diagnoses Bell’s palsy; steroids are started.
- 6 Evaluate
She demonstrates instilling tears and taping the eye for sleep, knows to return at once for eye pain, photophobia or a gritty feeling, and to follow up if there is no improvement after 3 weeks.
Scenario — you’re the nurse
Work each question before revealing the answer. Rationales explain the wrong options too.
A 34-year-old woman, 30 weeks pregnant, woke with the right side of her face ‘dropped’. She cannot wrinkle her right forehead or fully close her right eye, and her tea dribbled out of the right side of her mouth. She had an ache behind her right ear yesterday. She has no arm or leg weakness and her words are understandable, though lip sounds are slightly unclear — a change that still needs a stroke assessment.
Q1 Multiple choice A patient reports a new droop of one side of the face. What should the nurse do first? - A. Assess for arm weakness and speech difficulty and escalate as a possible stroke
- B. Reassure the patient that Bell’s palsy is usually temporary
- C. Apply a warm compress to the face
- D. Give an antiviral medication
Reveal answer & rationale
Q2 Multiple choice Which statement about forehead involvement is correct? - A. A weak forehead proves the cause is Bell’s palsy, not stroke
- B. Bell’s palsy weakens the whole half-face, but a brainstem stroke can also involve the forehead
- C. Bell’s palsy always spares the forehead
- D. Forehead findings do not matter
Reveal answer & rationale
Q3 Select all that apply Which eye-care measures are appropriate for a patient with Bell’s palsy who cannot fully close the eye? Select all that apply. - A. Artificial tears during the day
- B. Lubricant ointment at night
- C. Taping the eyelid closed at bedtime
- D. Report eye pain or light sensitivity immediately
- E. Stop eye care once the eye seems to close by itself on day 1
Reveal answer & rationale
Q4 Select all that apply A patient newly started on carbamazepine for trigeminal neuralgia asks how to take it. Which teaching is correct? Select all that apply. - A. Take it regularly every day, not only when pain starts
- B. Report a rash, fever, sore throat or easy bruising immediately
- C. Use a back-up method of contraception
- D. Stop it suddenly once the pain goes away
Reveal answer & rationale
Q5 Multiple choice Which finding in a patient with trigeminal neuralgia should the nurse report as a possible secondary cause? - A. Pain triggered by brushing the teeth
- B. Numbness of the cheek and an absent corneal reflex in a 32-year-old
- C. Attacks lasting a few seconds
- D. No pain during sleep
Reveal answer & rationale
Common questions
What causes bell’s palsy & trigeminal neuralgia?
Which findings should a nurse report immediately in bell’s palsy & trigeminal neuralgia?
Which medications are used to treat bell’s palsy & trigeminal neuralgia?
Why protect the eye so carefully in Bell’s palsy?
Do painkillers help trigeminal neuralgia?
Does Bell’s palsy come back?
Sources
- Bell Palsy — StatPearls — StatPearls (NCBI Bookshelf)
- Trigeminal Neuralgia — StatPearls — StatPearls (NCBI Bookshelf)
- Facial Nerve Palsy — StatPearls — StatPearls (NCBI Bookshelf)
- Bell’s Palsy — NINDS — National Institute of Neurological Disorders and Stroke
- Trigeminal Neuralgia — NINDS — National Institute of Neurological Disorders and Stroke
- Bell’s palsy — NHS. Contains public sector information licensed under the Open Government Licence v3.0 (https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/) — NHS (UK)
- Trigeminal neuralgia — NHS. Contains public sector information licensed under the Open Government Licence v3.0 (https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/) — NHS (UK)
- TEGRETOL (carbamazepine) — FDA label — U.S. FDA / NLM DailyMed
Reviewed by Hae Suk Lee, RN
Educational summary for nursing students. Scenarios are fictional teaching cases. Always verify against current guidelines and your institution's protocols before acting in practice. Not medical advice.