Which finding is most characteristic of bulbar onset ALS?

• A. Limb weakness with sensory symptoms
• B. Jaw fatigue and chewing difficulties
• C. Respiratory weakness with sleep apnea
• D. Tongue fasciculations/atrophy

Answer: (D)

Bulbar onset ALS targets the motor neurons in the brainstem that control muscles used for speech and swallowing. The tongue is innervated by the hypoglossal nerve, so degeneration of these neurons produces visible tongue fasciculations and progressive atrophy, which are hallmark signs of bulbar involvement. This makes tongue changes the most characteristic finding in bulbar onset, more distinctive than limb weakness with or without sensory symptoms, which is not typical in ALS, or respiratory weakness with sleep-related breathing issues, which aren’t specific bulbar signs. Jaw fatigue and chewing difficulties can occur, but they are less specific than the clear LMN changes seen in the tongue.