A Speech-Language Pathologist’s Contribution to Localizing and Diagnosing Neurologic Disease
By: Michelle Saade & Lindsey Norton
An SLP’s Role in a Neurologic Diagnosis
While many Speech-Language Pathologists (SLP) see patients who have already received a diagnosis, an SLP may actually be the first professional to assess a patient’s initial symptoms of an unknown pathology. These first impressions of the patient’s motor speech functioning may be crucial in pinpointing a patient’s neurologic disease process. Collaboration between SLPs and neurologists leads to more accurate evaluation and treatment goals for patients.
Pinpointing a Neurologic Diagnosis
In many cases, an SLP may be able to identify the neural substrates of a patient’s disease based on results of the oral mechanism and perceptual speech examinations. With confirmatory signs of site localization, the SLP is able to match various motor speech disorders to a specific list of possible disease processes. The information that the SLP provides to the neurologist is used during the process of differential diagnosis.
For example, in a case study described by Dr. Joseph Duffy, a 74-year old man presented with a 10-month history of speech difficulty that was getting progressively worse. Other examinations had found dysarthria to be his only issue. The neurologist decided to consult an SLP before making a final diagnosis. After the evaluation, the SLP stated that the patient had a “moderate spastic dysarthria which is strongly suggestive of a bilateral upper motor neuron dysfunction affecting the bulbar speech muscles.” The clinician also mentioned a possibility of lower motor neuron involvement. The neurologist ordered additional nerve tests based on the SLP’s report, and this led to a confirmed diagnosis of ALS (Duffy, 2008).
In this case, site localization of the presented motor speech disorder was integral to the neurologist’s diagnostic process. The manifestations of oromotor and speech deficits reflect underlying neurologic mechanisms. Changes or abnormalities in the motor speech system logically ‘map on to’ pathology in the nervous system. In fact, these relationships between neurologic disease and motor speech characteristics were closely studied in 1969 to comprehensively describe the correlations between various motor speech disorders and corresponding disease processes (Darley, Arnson & Brown, 1969).
Confirming or Disproving a Neurologic Diagnosis
Neurologic diseases may manifest themselves in a variety of ways, with a change in a person’s speech being just one. However, this specific symptom could make a significant difference in a person’s assessment, evaluation, or treatment. A case example mentions a 34-year old male who presents with symptoms of generalized dystonia (Duffy, 2008). The neurologist deemed deep brain stimulation surgery appropriate after the completion of a comprehensive exam, which included a speech-language evaluation. During the speech assessment, the clinician observed that the dysphonia increased when reading and became a strained whisper when counting. The patient reported noticing changes in his voice and being unable to speak. The clinician noted inconsistency between the speech samples in the evaluation session, claiming that the pattern was abnormal and not consistent with dystonia or any type of dysarthria. Upon continuation of the session, the SLP noted that the patient’s voice quality became almost normal for the remainder of the session. Concluding remarks of the clinician noted that the patient’s abnormal vocal quality was most likely related to muscular tension, rather than the predicted diagnosis of generalized dystonia. Upon considering the SLP’s report, the neurologist then ordered additional testing to be performed, and concluded that the man’s case was psychogenic. His DBS surgery was cancelled.
This example stresses the importance of an SLP in coming up with an appropriate diagnosis for a patient presenting with several symptoms. Had it not been for the speech evaluation, the patient may have gone on to get surgery that would not have improved his condition. This goes to show that the role of an SLP in diagnosing neurologic disease is oftentimes underestimated. In many cases, the neurologic diagnosis of a disease is largely dependent on feedback from the SLP’s evaluation (Duffy, 2005).
Darley, F. L., Aronson, A. E., & Brown, J. R. (1969). Differential diagnostic patterns of dysarthria. J Speech Hear Res. 12(2), 246-269. Doi: 10.1044/jshr.1202.246.
Duffy, J. R. (2008). Motor speech disorders and the diagnosis of neurologic disease. The ASHA Leader, 13(16), 10-13. Doi: 10.1044/leader.FTR1.13162008.10.
Duffy, J. R. (2005). Apraxia of speech in degenerative neurologic disease. Journal Aphasiology, 20 (6), 511-527.