“The investigation of nature is an infinite pasture ground where all may graze, and where the more bite, the longer the grass grows, the sweeter is its flavor and the more it flourishes.” —Aldous Huxley (1894–1963)
On completion of this chapter, the student/practitioner will be able to:
To gain appreciation of the hypothesis-oriented algorithm for clinicians as a method of improving efficiency and timeliness of the evaluation process for patients with suspected peripheral neuropathy.
To be able to differentiate screening versus diagnostic laboratory testing.
To use clinical laboratory testing results as an important adjuvant to the diagnostic process.
To begin to correlate laboratory data with the physical examination to add to, remove, or confirm the differential diagnoses.
For most presentations of suspected peripheral neuropathy, the logical starting point for the diagnostician is the patient interview and review of prior laboratory, electrodiagnostic, and radiographic data. Visual and audible clues provided by the patient during the taking of the medical/surgical history and history of the present illness and hard data from the prior diagnostic workup allow the clinician to begin to develop a differential diagnosis list. The Hypothesis-Oriented Algorithm for Clinicians (HOAC) and the later iteration, HOAC II1 provide a logical diagnostic framework for the clinician. Initial “clinical scripts” provide clues enabling the clinician to begin to develop a list of differential diagnoses. The clinician can then eliminate from, add to, or confirm the list of differential diagnoses through the application and analysis of additional evaluative data obtained from performing the physical examination, ordering additional radiological and laboratory testing, or asking qualifying questions to the patient about the history presented. The HOAC framework allows for a systematic and orderly search for the differential diagnoses rather than the “shotgun” method of ordering batteries of tests and measures and performing unnecessary physical examination tests and measures. As research continues to improve the sensitivity and specificity of diagnostic utilities, the use of frameworks such as the HOAC will improve the cost-effectiveness and timeliness of diagnostic work (Fig. 13-1).
Example of a diagnostic algorithm for the evaluation of suspected peripheral neuropathy. The algorithm was developed by the author and reflects the Hypothesis-Oriented Algorithm developed by Rothstein et al. (From Rothstein JM, Echternach JL, Riddle DL. The hypothesis-oriented algorithm for clinicians II (HOAC II): a guide for patient management. Phys Ther. 2003;83(5):455–470.)
Adjuvant to the physical examination, the clinician relies on additional tests and measures to provide data to help narrow, add to, or confirm the differential list of neuropathic diagnoses. These include the electroneuromyogram, radiographic studies, autonomic testing, biopsy, and laboratory testing.