• The Step 1 Newsletter
  • Posts
  • Which nerve's electrical stimulation could address the underlying pathophysiology of his symptoms?

Which nerve's electrical stimulation could address the underlying pathophysiology of his symptoms?

Author

Dr. Shoaib Ahmad Baig
December 10, 2024

Question

A 57-year-old man presents with unrefreshing sleep, daytime fatigue, and occasional napping during lunch. His wife reports loud snoring and gasping for breath at night. He has severe claustrophobia, a history of hypertension, and a BMI of 32 kg/m². Examination reveals a bulky tongue and a crowded oropharynx. Blood pressure is 156/94 mm Hg.

Which nerve's electrical stimulation could address the underlying pathophysiology of his symptoms?

  • Hypoglossal

  • Lingual

  • Maxillary

  • Phrenic

  • Recurrent laryngeal

Correct Answer: Hypoglossal Nerve

🧠 Step 1: Understanding the Scenario

  • Patient Clues:

    • 💤 Loud snoring, gasping, and unrefreshing sleep → Think OSA!

      (Obstructive Sleep Apnea)

    • 🔍 BMI ↑ (30 kg/m²) + bulky tongue + narrow oropharynx → Obstructive cause likely

    • 🔍 Hypertension + daytime fatigue → Consequence of fragmented sleep

    • ⚖️ Severe claustrophobia → CPAP intolerance, alternative treatments needed.

🧠 Underlying Cause
⬇
Obesity (BMI ↑)
⬇
Bulky tongue & crowded oropharynx
⬇
Narrowed upper airway

Airway Patency During Sleep ⬇
⬇
↓ Muscle tone in upper airway (sleep-induced relaxation)
⬇
Upper airway collapse
⬇
Obstruction to airflow

⬇

Ventilation
⬇
Hypoxia (↓ O₂) + Hypercapnia (↑ CO₂)
⬇
Recurrent arousals (to restore airway patency)
⬇
Sleep fragmentation

⬇

Consequences
⬇
Daytime fatigue & unrefreshing sleep
⬇
Loud snoring & gasping during sleep
⬇
↑ Sympathetic activation
⬇
Hypertension (BP: 156/94 mmHg)

🔍 Why symptoms occur?
→ Gasping & loud snoring: Turbulent airflow during partial obstruction.
→ Daytime fatigue: Poor sleep quality due to arousals (↓ REM/NREM cycles).
→ Hypertension: Sympathetic overdrive during apneic episodes.

🔍 What resolves the problem?
→ Keep airway open → Prevent collapse → Hypoglossal nerve stimulation is key!


⚙️ Mechanism:

  • Hypoglossal nerve 🧠 → Activates genioglossus muscle ⚙️ → Tongue moves forward → Airway patency ↑ → Stops obstruction

Explanation of Other Answers ⚖️

Option

Mechanism ⚙️

Role in OSA

Lingual nerve

Sensory to tongue 🧠

🚫 No effect on airway tone.

Maxillary nerve

Sensory to midface 🧠

🚫 Unrelated to airway obstruction.

Phrenic nerve

Controls diaphragm movement ⚙️

🚫 Helps with central apnea, not OSA.

Recurrent laryngeal nerve

Vocal cord innervation 🧠

🚫 Vocal cords don’t cause airway collapse in OSA.

Flashcards

Stay Hungry, Stay Curious!

Your Brother In This Struggle

Dr. Shoaib Ahmad