A 45-year-old man presents to a physician due to difficulty swallowing and slurred speech. For the past 3 months, the patient has been coughing when he drinks liquids. His speech also sounds different according to his wife. The patient has no significant medical history. His temperature is 98.6°F (37.0°C), blood pressure is 110/80 mmHg, pulse is 60/min, and respirations are 12/min. On physical exam, he is unable to fully extend his tongue, and there are fasciculations on his tongue. When tapping the mandible at the chin while the mouth is held open, there is pronounced upward movement of the lower jaw. Sensory exam reveals no deficits. Which of the following therapies is most likely to improve survival for this patient's disease process?
Dextromethorphan and quinidine
Tizanidine
Riluzole
Edaravone
Riluzole
This patient with dysphagia (difficulty swallowing water), dysarthria (altered and slurred speech), lower motor neuron deficits (tongue fasciculations and weakness), upper motor neuron deficits (exaggerated jaw jerk reflex), and preserved sensory function most likely has amyotrophic lateral sclerosis (ALS). Riluzole, a glutamate inhibitor, is currently the only Food and Drug Administration (FDA) approved medication that improves survival in patients with ALS.

ALS is a neurodegenerative disease that affects both upper and lower motor neurons. Upper motor neuron signs include spasticity and hyperreflexia, while lower motor neuron signs include muscle atrophy and fasciculations (spontaneous, involuntary muscle contraction and relaxation). In patients with bulbar-onset ALS, the initial clinical presentation is dysarthria, dysphagia, tongue atrophy, and abnormal jaw jerk reflex. Riluzole decreases the rate of glutamate release from presynaptic neurons, which is thought to decrease excitatory neurotoxicity. Riluzole improves survival by 2-6 months in patients with ALS and may have a greater survival benefit in patients with bulbar-onset ALS.

Masori and Van Damme review the genetics, pathophysiology, classic clinical presentation, extra-motor manifestations, diagnostic workup, and treatment for ALS. They discuss how riluzole provides a survival benefit in patients with this disease. They recommend treating patients with ALS using riluzole as tolerated.

Incorrect Answers:
Answer A: Baclofen is a gamma-aminobutyric acid (GABA) agonist that reduces the release of excitatory neurotransmitters to decrease spasticity in ALS. Along with tizanidine, baclofen is a first-line symptomatic treatment for spasticity in ALS. Baclofen does not improve survival in ALS.

Answer B: Dextromethorphan and quinidine is a combination of a sigma opioid receptor agonist and a sodium channel blocker used to control pseudobulbar affect in patients with ALS. Pseudobulbar affect is a sudden uncontrollable outburst of laughter or tearfulness that affects almost half of patients with ALS. Dextromethorphan and quinidine has not been shown to improve survival in ALS.

Answer C: Edaravone is an intravenous antioxidant that may decrease the progression of early ALS. Although it is now FDA approved, studies have not yet shown that edaravone improves survival in patients with ALS. Further studies will be needed in order to determine the risks and benefits of using this drug.

Answer E: Tizanidine is a central alpha-2-adrenergic receptor agonist that decreases spasticity in ALS by increasing presynaptic inhibition of motor neurons. Excess spasticity in ALS can negatively impact coordination, ambulation, and other activities of daily living. Tizanidine and other antispastic medications do not improve survival in patients with ALS.

Bullet Summary:
Riluzole is a glutamate inhibitor that improves survival in patients with amyotrophic lateral sclerosis.