A Rare Case of Amyotrophic Lateral Sclerosis With Asymmetrical Phrenic Nerve Lesion Presenting With Acute Respiratory Failure as an Initial Manifestation

Abstract

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder that causes muscle weakness, disability, and eventually, death. Respiratory failure is the leading cause of death in ALS. It is common in the advanced stages of the disease. However, acute respiratory failure is a presenting symptom in only a small number of patients, such as in our case. Here, we present the case of a 54-year-old woman with ALS presenting with respiratory failure due to unilateral diaphragm paralysis as the first manifestation. Although rare, respiratory muscle function failure can be the first symptom of motor neuron disease. Therefore, a motor neuron disease such as ALS, which leads to respiratory muscle weakness and diaphragm paralysis, should be considered in cases of unexplained acute respiratory failure.

Keywords: acute hypoxemic respiratory failure; amyotrophic lateral sclerosis; lower motor neuron lesion; motor neuron disease; phrenic nerve; upper motor neuron lesion.

Figure 1. Patient on mechanical ventilation.

Figure 2. Distal atrophy of the leg muscles bilaterally.

Figure 3. Repetitive nerve stimulation on right ADM.

ADM, abductor digiti minimi

Figure 4. Electroneuromyography of the right and left phrenic nerves.

LPN, left phrenic nerve; RPN, right phrenic nerve

Figure 5. Fasciculations as a sign of denervation (A), and discrete recruitment pattern in deltoid muscle (B).

Figure 6. (A) Patient on mechanical ventilation (99% saturation). (B) One minute after weaning from the ventilator (93% saturation).