These two live next door to each other in the face and get mixed up constantly. They are not
the same nerve and not the same problem.
Bell's palsy = cranial nerve VII (facial) = a MOTOR problem — one whole side of the face stops moving,
including the forehead, and the eye will not close, so eye protection is the nursing priority.
Trigeminal neuralgia = cranial nerve V (trigeminal) = a SENSORY problem — sudden, severe, stabbing
one-sided facial pain set off by light touch, chewing or cold air, treated by avoiding triggers and with
carbamazepine. Get the numbers and the motor-vs-sensory the right way round and the rest follows.
😐 BELL'S = CN VIIMOTOR. One side droops — forehead included — and the eye will not close.
👁️ EYE FIRSTArtificial tears, ointment, tape/patch at night. The droop resolves; a corneal ulcer does not.
⚡ TRIGEMINAL = CN VSENSORY. Sudden electric-shock pain on one side, set off by touch, chewing or cold air.
💊 CARBAMAZEPINEFirst-line for trigeminal neuralgia. Avoid triggers. Stroke spares the forehead — Bell's does not.
🔢
TWO DIFFERENT NERVES
STEP 1 · CAUSE
Before anything else: get the numbers and the jobs right. Everything on this page depends on it.
⭐ The whole page in one card
🧠 V comes BEFORE VII — you FEEL something first (V, sensory), then you MOVE (VII, motor). Same order as the numbers.
😀 CN VII — the nerve that MOVES the face
One trunk leaves the skull just in front of the ear, passes through the parotid gland and fans into five branches. Because it is one nerve, damaging it takes out the entire half of the face — forehead, eye, cheek and mouth.
🧠 “Ten Zebras Bit My Cat” — Temporal, Zygomatic, Buccal, Marginal mandibular, Cervical.
🖐️ CN V — the nerve that FEELS the face
Three divisions, three stripes down the face. V1 ophthalmic across the forehead and cornea, V2 maxillary across the cheek and upper lip, V3 mandibular across the jaw and lower lip. V3 also carries the motor supply to the chewing muscles — the one motor job the trigeminal has.
🧠 Trident gum — you chew on the GEMs in triGEMinal. Three prongs, three divisions, and chewing.
🧠 Where they come from
Both nerves leave the pons (brainstem) and travel forward into the face — which is why they are neighbors and why they get confused.
CN V exits the side of the pons as a thick sensory root, forms the trigeminal ganglion, then splits into V1, V2 and V3
CN VII exits at the pontomedullary junction, runs through the facial canal in the temporal bone, then out to the face
That bony canal matters: swelling inside it has nowhere to go, so it squeezes the nerve.
🧠 A swollen nerve in a bony tunnel has nowhere to swell. That is Bell's palsy in one line.
🔎 CN VII does more than move
It is mainly motor, but it also carries:
Taste from the anterior two-thirds of the tongue
Parasympathetic supply to the tear and salivary glands
The nerve to stapedius in the middle ear
That is why Bell's palsy can also cause altered taste, a dry eye or excess tearing, and hyperacusis — ordinary sounds feeling painfully loud.
🧠 Face, taste, tears, loud sounds. Four extras that confirm it is CN VII.
😐
BELL'S PALSY — CN VII, MOTOR
SIDE A
Sudden, one-sided, whole-side facial weakness. Usually temporary. The eye is the emergency.
😐 What it looks like
Ask the patient to raise the eyebrows, close the eyes tightly, show the teeth and puff the cheeks. In Bell's palsy the affected side fails at every one of them.
🧠 “FELLS palsy” — the face FALLS to one side.
📖 What it actually is
Inflammation and swelling of cranial nerve VII, producing an acute lower motor neuron facial palsy on one side.
Onset over hours to a couple of days
Unilateral — one side only
Complete: forehead, eyelid, cheek and mouth
Cause often unknown; commonly linked to reactivation of herpes simplex, and to varicella-zoster (Ramsay Hunt, with a painful vesicular rash in the ear), Lyme disease and other infections
Risk is higher in pregnancy and in diabetes
🧠 A virus wakes up, the nerve swells, the tunnel squeezes.
👀 The signs, in the order you will see them
Cannot wrinkle the forehead or lift the eyebrow on that side
Cannot close the eye fully (lagophthalmos); the eyeball rolls up when they try — Bell's phenomenon
Flattened nasolabial fold
Mouth droops; the smile is one-sided
Drooling; food pockets in the affected cheek
Dry eye or excessive tearing on that side
Altered taste; hyperacusis
Ache behind or below the ear may come first
Balance is not affected and they can still drive once vision is protected — a common teaching point.
🧠 Top to bottom on ONE side.
🚨 The nursing priority: protect that eye
The eye cannot close, the blink is gone and tear production may be reduced. The cornea dries within hours. Never send a Bell's palsy patient home without an eye plan.
🧠 Tears by day, ointment and tape by night, sunglasses outside.
💊 Treatment
Corticosteroids started early — ideally within the first 72 hours — improve the chance of full recovery
Antiviral therapy is sometimes added, particularly if a herpes-type cause is suspected
Warm, moist heat to the affected side for comfort HESI
Gentle facial massage and facial exercises in front of a mirror
Analgesia for the ache
Eye care as above — the part that must not be missed
🧠 Steroids early, heat for comfort, tears for the eye.
🍽️ Eating & mouth care
Soft diet; small bites
Chew on the unaffected side
Check the affected cheek for pocketed food after every meal
Oral hygiene after meals — food sits against the gums on the weak side
Sit upright; take time; avoid very hot foods (reduced sensation on the tongue)
Weigh regularly if intake has dropped
🧠 Chew on the GOOD side, clean the BAD side.
📅 What to tell them about recovery
Most people improve within weeks and recover fully within 3–6 months
A minority are left with some residual weakness
Recurrence is uncommon but possible
It is not a stroke and it is not contagious
Report any eye pain, redness or vision change immediately
The psychological impact is real — a visibly altered face is distressing. Acknowledge it.
🧠 “It looks frightening and it usually goes away.” Say both halves.
⚡
TRIGEMINAL NEURALGIA — CN V, SENSORY
SIDE B
No droop, no weakness. Just some of the worst pain in medicine, set off by a breeze.
⚡ Where the pain is and what sets it off
Attacks are brief — seconds to about two minutes — but come in clusters, and patients often stop eating, washing or talking to avoid setting one off.
🧠 The wind can hurt them. That single image tells you how severe it is.
📖 What it actually is
Irritation or compression of cranial nerve V producing sudden, severe, unilateral facial pain described as an electric shock or a stabbing.
Usually in the V2 and/or V3 distribution — cheek, jaw, gums, lips, teeth
Almost always one side only
Seconds to ~2 minutes per attack, then a pain-free gap
No weakness, no droop, no rash
🧠 Trident gum — you're chewing on GEMs in triGEMinal.
🩸 Why the nerve misfires
A pulsating artery loop rubbing against the nerve root strips the myelin, so ordinary touch signals cross over into pain fibers. MS can do the same thing by demyelinating that root — which is why a younger patient with trigeminal neuralgia gets an MRI.
🧠 A frayed wire shorts out. Touch goes in, lightning comes out.
💊 Carbamazepine — the classic drug
Carbamazepine is an anticonvulsant and the first-line treatment. It slows the nerve firing so the misfires stop. Oxcarbazepine, baclofen and gabapentin are alternatives.
Monitoring — this drug is not gentle:
CBC — risk of agranulocytosis and aplastic anemia; report sore throat, fever, bruising
Liver function tests
Serum sodium — carbamazepine can cause hyponatremia
Serum drug levels
Any rash is reported immediately — risk of Stevens-Johnson syndrome
Many drug interactions — always check
Drowsiness and dizziness, especially at the start; caution with driving
Never stop an anticonvulsant abruptly.
🧠 CarBAMazepine — check the Blood, the liver, And the sodium; Mind the rash.
🛡️ Avoiding triggers is the teaching
Serve food and drink at room temperature — not hot coffee, not ice-cold drinks
Avoid caffeine if it is a trigger for them
Soft foods; small bites; chew on the unaffected side
Wash the face with cotton pads and lukewarm water; let the patient do it themselves so they control the touch
Avoid drafts — car vents, air conditioning, fans, cold wind. A scarf outdoors helps
Electric razor rather than a blade; brush teeth gently with lukewarm water
Keep the room warm and draft-free; approach from the unaffected side
Do not touch the face without warning them first
🧠 Room temperature, cotton pads, no drafts, warn before you touch.
🔪 When drugs stop working
Microvascular decompression — a padding is placed between the artery and the nerve; the most durable option
Stereotactic radiosurgery (gamma knife)
Percutaneous rhizotomy — radiofrequency, balloon or glycerol injury to the ganglion
Ablative procedures can leave facial numbness and may abolish the corneal reflex — so post-operatively these patients need eye protection too, and must be taught not to chew on the numb side or drink anything very hot.
🧠 Trade pain for numbness — then protect what cannot feel.
🚨 Do not underestimate this pain
The priority action for a patient in an attack is to assess the painKAPLAN
Weight loss and dehydration are common — they avoid eating and drinking
Poor oral hygiene from avoiding tooth-brushing
Social withdrawal; they stop talking and going out
Screen for depression and suicidal ideation — this condition has historically been called “the suicide disease” for a reason
🧠 Ask about mood, weight and teeth. The pain damages all three.
🔍
TELL THEM APART
STEP 4 · COMPARE
Bell's vs trigeminal, and — the higher-stakes one — Bell's vs stroke.
⚖️ Bell's palsy vs trigeminal neuralgia
Bell's palsy
Trigeminal neuralgia
Cranial nerve VII (facial)
Cranial nerve V (trigeminal)
MOTOR problem — it cannot move
SENSORY problem — it hurts
Facial droop, one whole side
Facial pain, stabbing, one side
Eye will not close
Eye moves and closes normally
Usually painless (may ache behind the ear)
Severe, paroxysmal pain
Constant until it recovers
Comes in brief attacks with pain-free gaps
Triggered by nothing
Triggered by touch, chewing, cold air
Priority: EYE PROTECTION
Priority: PAIN & trigger avoidance
Drug: corticosteroids early
Drug: carbamazepine
Usually resolves in weeks–months
Chronic, relapsing; may need surgery
🧠 VII = the face WON'T MOVE. V = the face WON'T STOP HURTING.
🚨 Bell's palsy vs STROKE — the forehead test
This is the high-yield differentiator. Bell's palsy involves the forehead; a stroke typically spares it. If the patient can still wrinkle their forehead and close that eye, think central — and treat it as a stroke until proven otherwise.
🧠 Forehead works = brain problem. Forehead dead = nerve problem.
🚨 Other stroke red flags with a facial droop
Arm or leg weakness, or numbness, on the same side