The various manifestations of what is termed “motor neuron disease” are primarily lower motor neuron involvement, primarily upper motor neuron involvement, primarily progressive bulbar paresis, or most commonly, the combination of upper motor neuron (long tract signs with spastic weakness and hyperreflexia) and lower motor neuron signs (atrophic weakness with fasciculations) often referred to as amyotrophic lateral sclerosis (ALS). The involvement of the bulbar musculature heralds a worse prognosis in terms of swallowing and speech difficulty as well as respiratory involvement. The diagnosis must be established with as much certainty as possible and involves not only a detailed history and thorough neurologic exam but also an electomyogram with nerve conduction velocities. This neurophysiologic study is vitally important and often requires considerable expertise.

If there’s any question about the diagnosis, refer to a center with particular expertise in motor neuron disease because the implications of the diagnosis include death, often within several years from onset. However, this can very much depend on the manifestations and the level of supportive care warranted and requested. It is very important not to “give up” on the patient; monitoring the neurologic condition over time can provide considerable emotional support for both the patient and the family.

The recent evidence-based review from the American Academy of Neurology (AAN) recommends considering riluzole to slow the disease progression, percutaneous endoscopic gastrostomy (PEG) to stabilize the patient’s weight and to prolong survival, and noninvasive ventilation (NIV) to treat respiratory insufficiency in an effort to prolong survival.¹

In an accompanying article, the authors recommend referral to a multidisciplinary clinic should also be considered to improve the quality of life and to ensure that an extra effort is being made to address what can be considerable management needs. Refractory sialorrhea may respond to boxulinum toxin B or low-dose radiation to the salivary glands. Dextromethorphan and quinidine may prove helpful for pseudobulbar affect if approved by the FDA. The authors point out that the excessive fatigue which can be associated with use of riluzole, if counterproductive for the patient, should lead to consideration of its discontinuation. The authors also point out the importance of monitoring for cognitive and behavioral manifestations, including dementia. Despite the limited therapeutic options presently available for ALS, supportive measures and patients’ access to them must be kept in mind for this often devastating neurologic disorder.²

References

1. Miller RG, Jackson CE, Kasarskis EJ, et al. Practice Parameter update: The care of the patient with amyotrophic lateral sclerosis: Drug, nutritional, and respiratory therapies (an evidence-based review). Neurology. 2009;73:1218-1226.
2. Miller RG, Jackson CE, Kasarskis EJ, et al. Practice Parameter update: The care of the patient with amyotrophic lateral sclerosis: Multidisciplinary care, symptom management, and cognitive/behavioral impairment (an evidence-based review). Neurology. 2009;73:1227-1233.