AMYOTROPHICLATERAL SCLEROSIS

AMYOTROPHICLATERAL SCLEROSIS

Amyotrophic lateral sclerosis (ALS) is an idiopathic disorder of both upper and lower motor neurons. ALS has a unique presentation of muscle weakness combined with signs of upper motor neuron loss, cranial nerve palsies, respiratory involvement, and lower motor neu-   ron destruction, while at the same time preserving bowel, bladder sensory, cognitive, and sexual function. The cranial nerve, or bulbar, palsies result in dysphagia, difficulty chewing, decreased gag reflex, dysarthria (difficulty in articulating words), and difficulty in handling saliva. Since there is often respiratory muscle involvement, recurrent aspiration pneumonia is the most common cause of death. A weak cough is also characteristic, and this only worsens the respiratory problem.

There is no pain from abnormal sensory neuropathy because this is entirely a motor neuron disease. On the other hand, the upper motor neuron involvement gives significant spasticity that can lead to pain. Mentation, bowel, bladder, and sexual function remain intact for the same reason. In other words, a fully mentally alert patient loses nearly all motor control while still being able to think and perceive. The patient becomes fully aware of being trapped in a body that does not function. Head ptosis occurs because the extensor muscles of the neck become too weak to keep the head up.

Upper motor neuron manifestations are weakness with spasticity and hyperreflexia. Lower motor neuron manifestations are weakness with muscle wasting, atrophy, and fasciculations; this includes tongue atrophy. The combination of upper and lower motor neuron weakness is the unique presentation of ALS. The most accurate confirmatory test is the electromyogram, which will show diffuse axonal disease. CPK levels are sometimes mildly elevated, and the cerebrospinal fluid and MRI scans are normal.

The only treatment that may slow down the progression of  the disease is riluzole, which     is thought to work by inhibiting glutamate release. Death typically results in 3–5 years. Spasticity is treated with baclofen and tizanidine.

Many of the exam questions regarding ALS will be ethical questions on issues of the with- holding of care. Since ALS has no impact on cognitive function, the patient is felt to retain the capacity to make medical decisions. This means the patient has the right to refuse potentially lifesaving therapy such as antibiotics, nasogastric tube placement, tracheostomy, or the use of mechanical ventilation. The patient should not be allowed to commit suicide nor should the physician assist with the suicide. Withholding intubation or antibiotics is not considered assisting a suicide. Every adult patient with the capacity to understand the implications of their choice is allowed to refuse any therapy they do not want.