# Clinical Cases: Cranial Nerve Disorders

## Case 1: Bell's Palsy

### Patient Demographics
- **Age:** 38 years
- **Sex:** Female
- **Occupation:** Marketing manager

### Chief Complaint
"I woke up and couldn't move the left side of my face."

### History of Present Illness
The patient woke up this morning and noticed her face felt "different." When she looked in the mirror, she was alarmed to see that the left side of her face was drooping. She cannot close her left eye completely, cannot smile on the left side, and food falls out of the left side of her mouth when eating. She noticed some pain behind her left ear yesterday evening, which she attributed to sleeping in an awkward position. She also reports that sounds seem unusually loud in her left ear (hyperacusis) and that food tastes "strange" on the left side of her tongue. No hearing loss, no vertigo, no other weakness or numbness. She had a viral upper respiratory infection about 2 weeks ago. She has no history of diabetes, no rash, no recent travel, and no tick exposure.

### Neurological Examination Findings

**Mental Status:**
- Alert, oriented, anxious about facial appearance
- Speech: Slightly slurred due to facial weakness

**Cranial Nerves:**

**CN VII (Facial) - LEFT SIDE:**
- **Complete left facial paralysis affecting ENTIRE hemiface**
- **Forehead:** Cannot wrinkle forehead or raise eyebrow on left
- **Eye:** Cannot close left eye completely (Bell's phenomenon present - eye rolls up on attempted closure)
- **Mouth:** Cannot smile, show teeth, or puff cheek on left
- Nasolabial fold flattened
- Mouth droops to left at rest
- **Taste:** Decreased on anterior 2/3 of tongue on left (chorda tympani)
- **Hyperacusis on left** (stapedius involvement)

**Other Cranial Nerves:**
- CN I: Intact
- CN II: Visual acuity 20/20 OU, visual fields full, pupils equal and reactive, no papilledema
- CN III, IV, VI: Extraocular movements full, no ptosis, no diplopia
- CN V: Facial sensation intact, corneal reflex present (sensory intact, motor impaired on left due to VII)
- CN VIII: Hearing grossly intact bilaterally by finger rub, no nystagmus
- CN IX, X: Palate elevates symmetrically, gag intact
- CN XI: Trapezius and SCM 5/5 bilaterally
- CN XII: Tongue midline, no atrophy

**Motor, Sensory, Reflexes:**
- All within normal limits
- No other weakness
- Normal gait

**Skin Examination:**
- No vesicular rash in or around ear (ruling out Ramsay Hunt syndrome)
- No erythema migrans (ruling out Lyme disease)

### Key Clinical Features
1. **Peripheral facial weakness** - entire hemiface involved including forehead
2. **Sudden onset** - developed overnight
3. **Associated features:** Hyperacusis (stapedius), taste changes (chorda tympani), retroauricular pain
4. **No other cranial nerve involvement**
5. **No rash** - distinguishes from Ramsay Hunt syndrome

### Central vs Peripheral Facial Weakness

| Feature | Bell's Palsy (Peripheral) | Stroke (Central) |
|---------|---------------------------|------------------|
| Forehead | **Affected - cannot raise eyebrow** | **Spared** - can raise eyebrow |
| Eye closure | Incomplete | Usually preserved |
| Taste | May be affected | Not affected |
| Hyperacusis | May be present | Absent |
| Other deficits | Isolated facial weakness | Often hemiparesis, aphasia |

### Diagnosis
**Bell's Palsy (Idiopathic Peripheral Facial Nerve Palsy)**
- Diagnosis of exclusion
- Likely related to HSV-1 reactivation in geniculate ganglion

### House-Brackmann Grading
- Grade IV (Moderately Severe): Obvious weakness, incomplete eye closure, asymmetric mouth movement

### Management

**Pharmacological Treatment (started within 72 hours - ideal):**

1. **Prednisone 60-80 mg daily for 7 days** (or taper over 10 days)
   - Strong evidence for improved recovery
   - Started immediately in this patient

2. **Valacyclovir 1000 mg TID for 7 days** (optional, consider for severe cases)
   - Evidence less robust than steroids
   - May provide modest additional benefit in severe/complete paralysis
   - Added in this patient due to complete paralysis

**Eye Protection (CRITICAL):**
1. **Artificial tears** - apply every 2 hours while awake
2. **Lubricating eye ointment** - apply at bedtime
3. **Moisture chamber or tape** - tape eyelid closed at night
4. **Sunglasses** - protect from debris and wind
5. **Ophthalmology referral** if unable to close eye or corneal symptoms

**Patient Education:**
- Prognosis: ~85% will recover completely
- Recovery typically begins within 3 weeks, complete by 6 months
- Return immediately if: New weakness elsewhere, rash appears, hearing loss
- Avoid driving if unable to close eye (impaired peripheral vision)

**Follow-up:**
- Re-evaluate in 1 week
- Consider EMG/nerve conduction studies if no improvement by 3 weeks
- Refer to facial nerve specialist if no recovery by 6 months

### Prognosis
**Favorable factors in this patient:**
- Young age
- No diabetes
- Incomplete paralysis initially not present (but developed)
- Early treatment

**Expected outcome:** Good - 85% of Bell's palsy patients recover fully or nearly fully

### Potential Complications to Monitor
1. **Corneal abrasion/ulceration** - from incomplete eye closure
2. **Synkinesis** - aberrant regeneration causing involuntary movements
3. **Crocodile tears** - gustatory-lacrimal reflex (eating causes tearing)
4. **Persistent weakness** - in 15% of patients

### Clinical Image
![Bell's Palsy](case_01_image.jpg)

**Image Description:** Clinical photograph demonstrating left peripheral facial nerve palsy (Bell's palsy). Note the drooping of the left side of the face, inability to fully close the left eye, and asymmetric smile affecting the entire left hemiface including the forehead.

**Attribution:** Image from Wikimedia Commons. Licensed under CC BY-SA 3.0. Source: https://commons.wikimedia.org/wiki/File:Bell%27s_Palsy.png

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## Case 2: Vestibular Schwannoma (Acoustic Neuroma)

### Patient Demographics
- **Age:** 52 years
- **Sex:** Male
- **Occupation:** High school band teacher

### Chief Complaint
"I've been having trouble hearing in my right ear for the past year, and now my ear is ringing."

### History of Present Illness
The patient, a music teacher, first noticed difficulty hearing in his right ear about 18 months ago - he had trouble hearing students on his right side and began favoring his left ear on phone calls. The hearing loss has been gradually progressive. About 6 months ago, he developed constant high-pitched ringing (tinnitus) in his right ear. Over the past 3 months, he has noticed occasional mild imbalance, particularly when turning quickly, though no true spinning vertigo. He denies any facial weakness, numbness, or taste changes. He denies headache, nausea, or vomiting. He has no history of noise exposure beyond normal teaching environment, no ear infections, and no family history of hearing loss or tumors.

### Neurological Examination Findings

**Mental Status:**
- Alert, oriented, normal mood

**Cranial Nerves:**

**CN VIII (Vestibulocochlear):**
- **Right ear:** Decreased hearing to finger rub
- Left ear: Intact hearing
- **Weber test:** Lateralizes to LEFT (away from affected ear - sensorineural loss)
- **Rinne test:**
  - Right: Air conduction > bone conduction (positive Rinne, but both reduced)
  - Left: Air conduction > bone conduction (normal)
  - Confirms: Right sensorineural hearing loss (AC>BC but both decreased)

**CN VII (Facial):**
- Facial strength symmetric at rest and with movement
- No synkinesis
- Eye closure complete bilaterally
- **House-Brackmann Grade I** (normal)

**CN V (Trigeminal):**
- Facial sensation intact to light touch and pinprick
- Corneal reflex present bilaterally
- Masseter strength normal

**Other Cranial Nerves:**
- II: Visual acuity 20/25 OU, visual fields full, no papilledema
- III, IV, VI: Extraocular movements full, no nystagmus
- IX, X: Palate symmetric, gag intact
- XI, XII: Normal

**Cerebellar/Vestibular:**
- Finger-to-nose: Normal
- Heel-to-shin: Normal
- Gait: Normal, tandem gait intact
- Romberg: Negative (no significant imbalance)
- Head impulse test: Normal

**Motor, Sensory, Reflexes:**
- All within normal limits

### Neuro Workup

**Audiometry:**
- **Right ear: Asymmetric sensorineural hearing loss**
  - Moderate-to-severe high-frequency loss (4000-8000 Hz)
  - Word recognition score: 60% (reduced)
- Left ear: Normal hearing thresholds

**MRI Brain with Contrast (IAC Protocol):**
- **2.2 cm enhancing mass in right cerebellopontine angle**
- Extends into and expands the right internal auditory canal ("ice cream cone" appearance)
- Displaces but does not invade brainstem
- No hydrocephalus
- No other lesions
- Characteristic appearance of vestibular schwannoma

**Brainstem Auditory Evoked Responses (BAER):**
- Prolonged latency waves I-III on right (retrocochlear pathology)
- Normal on left

### Diagnosis
**Right Vestibular Schwannoma (Acoustic Neuroma)**
- Koos Grade II (extends into CPA, <2.5 cm)
- Sporadic (unilateral)

### Differential Diagnosis Considered
1. **Vestibular schwannoma** - most likely given imaging
2. Meningioma - typically dural-based, different enhancement pattern
3. Epidermoid cyst - non-enhancing, different signal characteristics
4. Facial nerve schwannoma - rare

### Rule Out NF2
- **Unilateral tumor** - most likely sporadic
- No cafe-au-lait spots
- No other tumors on imaging
- No family history
- If bilateral schwannomas were present, would diagnose Neurofibromatosis Type 2

### Management Options Discussed

**1. Observation with Serial Imaging:**
- Appropriate for small tumors (<1.5 cm)
- Patient preference for less invasive approach
- MRI every 6-12 months
- Risk: Tumor may grow, hearing may decline

**2. Stereotactic Radiosurgery (Gamma Knife):**
- Single high-dose focused radiation
- 90-95% tumor control rate
- Preserves serviceable hearing in 50-70%
- Facial nerve preservation >95%
- Lower immediate risk than surgery
- Long-term radiation risks (rare)

**3. Microsurgical Resection:**
- Definitive tumor removal
- Approaches: Retrosigmoid, middle fossa, translabyrinthine
- Hearing preservation possible with smaller tumors
- Facial nerve at risk (97% preservation at experienced centers)
- Recommended for: Large tumors, young patients, growing tumors

### Treatment Decision
- After multidisciplinary discussion (neurosurgery, radiation oncology, audiology)
- **Patient elected stereotactic radiosurgery** given:
  - Medium-sized tumor
  - Desire to minimize surgical risks
  - Some serviceable hearing remains
  - No facial weakness currently

### Follow-up Plan
1. Pre-treatment audiogram documented
2. Gamma Knife radiosurgery performed
3. MRI in 6 months, then annually
4. Audiometry annually
5. Monitor for: Facial weakness, hearing changes, trigeminal symptoms
6. Hearing aid evaluation for right ear

### Prognosis
- Tumor control with radiosurgery: >90% at 10 years
- Hearing preservation: 50-60% maintain serviceable hearing
- Facial nerve function: >95% maintain normal function
- May require surgery if tumor grows despite radiation

### Clinical Image
![Vestibular Schwannoma MRI](case_02_image.jpg)

**Image Description:** Axial T1-weighted MRI with contrast showing an enhancing mass in the right cerebellopontine angle extending into the internal auditory canal, characteristic of vestibular schwannoma (acoustic neuroma).

**Attribution:** Image from Wikimedia Commons. Licensed under CC BY-SA 3.0. Source: https://commons.wikimedia.org/wiki/File:Acoustic_neuroma.jpg

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## Key Teaching Points

### Bell's Palsy
1. **Peripheral = entire hemiface** (including forehead); Central = forehead spared
2. Most common cause of acute facial paralysis
3. **Start prednisone within 72 hours** - improves outcomes
4. **Eye protection is critical** - prevent corneal injury
5. 85% recover fully; poor prognostic factors include complete paralysis, age >60, diabetes
6. Always examine ear for vesicles (Ramsay Hunt) and consider Lyme disease

### Vestibular Schwannoma
1. **Classic triad:** Unilateral hearing loss, tinnitus, imbalance
2. Hearing loss is sensorineural - Weber lateralizes to normal ear
3. **MRI with contrast (IAC protocol)** is diagnostic imaging
4. Bilateral schwannomas = Neurofibromatosis Type 2
5. Treatment options: Observation, radiosurgery, microsurgery
6. Facial nerve preservation is a key surgical consideration