The Importance of Early Diagnosis of SMA

Arun S. Varadhachary, MD, PhD: Evaluation of a patient with spinal muscular atrophy (SMA) must begin at a higher cognitive level. Rather than focus immediately on SMA, the clinician should evaluate the patient for weakness. From the neuromuscular perspective, evaluating a patient for weakness localizes the symptoms to some aspect of the motor system, which consists of the brain, the spinal cord, the motor neurons in the spinal cord, the nerves, and, eventually, the muscles. By initiating the workup, the neurologist must recognize that the patient has weakness localized to the motor neurons within the spinal cord using electrode diagnostics, which can help distinguish nerve disorders from muscle disorders. The next step in the evaluation might be something traditional, like a muscle biopsy to help distinguish weakness between muscle and nerve to a higher degree of specificity. Finally, based upon the combined results of the muscle biopsy and the electrode diagnostics, the clinician likely would recognize that this patient has SMA. The neurologist then would confirm the diagnosis with a genetic test specifically seeking a mutation within the 5q SMN genes. The problem [of diagnosis taking a long time] has more to do with recognition of a problem. Specifically, in patients with type 3 SMA, the idea that there's something wrong may actually delay [medical consultation].

Many times, the progression of the disorder is relatively slow, which allows an individual to compensate. Only when that ability to compensate is exceeded does a [patient or family] seek medical attention. Without recognition of a problem, a diagnostic workup can't be initiated. The second problem is that later onset SMA is actually underappreciated. Although the prevalence of SMA types 2 and 3 is high, these conditions are not appreciated as a disorder that presents later, and many pediatricians and internists don't consider it. When a problem of weakness or the motor system is recognized and the individual begins working with a neurologist, the diagnosis should be made relatively quickly. The importance of early diagnosis gets to the heart of what it means to provide care for an individual. So many patients do not recognize that their functioning is not optimal and delay seeking medical help. If a diagnosis is made early, the individual has access to the tools and the resources that medical science has developed over the last number of years to assist optimal functioning. A neurologist is well positioned to recognize and understand the trajectory of the disorder, provide anticipatory guidance, and marshal the resources necessary to help that patient.