Louisiana Administrative Code
Title 40 - LABOR AND EMPLOYMENT
Part I - Workers' Compensation Administration
Subpart 2 - Medical Guidelines
Chapter 22 - Neurological and Neuromuscular Disorder Medical Treatment Guidelines
Subchapter A - Carpal Tunnel Syndrome (CTS) Medical Treatment Guidelines
Section I-2209 - Follow-Up Diagnostic Testing Procedures

Universal Citation: LA Admin Code I-2209

Current through Register Vol. 50, No. 9, September 20, 2024

A. Electrodiagnostic (EDX) studies are well established and widely accepted for evaluation of patients suspected of having CTS. The results are highly sensitive and specific for the diagnosis. Studies may confirm the diagnosis or direct the examiner to alternative disorders. Studies require clinical correlation due to the occurrence of false positive and false negative results. Symptoms of CTS may occur with normal EDX studies, especially early in the clinical course. EDX findings in CTS reflect slowing of median motor and sensory conduction across the carpal tunnel region due to demyelination. Axonal loss, when present, is demonstrated by needle electromyography in median nerve-supplied thenar muscles. Findings include fibrillations, fasciculations, neurogenic recruitment and polyphasic units (reinnervation).

1. Needle electromyography of a sample of muscles innervated by the C5 to T1 spinal roots, including a thenar muscle innervated by the median nerve of the symptomatic limb, is frequently required.

2. The following EDX studies are not recommended to confirm a clinical diagnosis of CTS:

a. Low sensitivity and specificity compared to other EDX studies: multiple median F wave parameters, median motor nerve residual latency, and sympathetic skin response

b. Investigational studies: evaluation of the effect on median NCS of limb ischemia, dynamic hand exercises, and brief or sustained wrist positioning

3. To assure accurate testing, temperature should be maintained at 30-34C preferably recorded from the hand/digits. For temperature below 30C the hand should be warmed.

4. All studies must include normative values for their laboratories.

5. Positive Findings Any of these nerve conduction study findings must be accompanied by median nerve symptoms to establish the diagnosis.

a. Slowing of median distal sensory and/or motor conduction through the carpal tunnel region

b. Electromyographic changes in the median thenar muscles in the absence of proximal abnormalities

c. Suggested guidelines for the upper limits of normal latencies:

i. Median distal motor latency (DML)-4.5msec/8cm

ii. Median distal sensory peak latency (DSL)-3.6msec/14cm

iii. Median intrapalmar peak latency (palm-wrist)-2.2msec/8cm

iv. Median-ulnar palmar sensory latency difference greater than 0.3msec

6. Because laboratories establish their own norms, a degree of variability from the suggested guideline values is acceptable.

7. In all cases, normative values are to be provided with the neurodiagnostic evaluation.

8. Suggested grading scheme by electrodiagnostic criteria for writing a consultation or report may be:

a. Mild CTS-prolonged (relative or absolute) median sensory or mixed action potential distal latency (orthodromic, antidromic, or palmar).

b. Moderate CTS-abnormal median sensory latencies as above, and prolongation (relative or absolute) of median motor distal latency.

c. Severe CTS-prolonged median motor and sensory distal latencies, with either absent or sensory or palmar potential, or low amplitude or absent thenar motor action potential. Needle examination reveals evidence of acute and chronic denervation with axonal loss.

9. Frequency of Studies/Maximum Number of Studies:

a. Indications for Initial Testing

i. patients who do not improve symptomatically or functionally with conservative measures for carpal tunnel syndrome over a three to four week period;

ii. patients in whom the diagnosis is in question;

iii. patients for whom surgery is contemplated;

iv. to rule out other nerve entrapments or a radiculopathy.

b. repeated studies may be performed:

i. to determine disease progression. 8-12 weeks is most useful when the initial studies were normal and CTS is still suspected.

ii. for inadequate improvement with non-surgical treatment for 8-12 weeks ;

iii. for persistent or recurrent symptoms following carpal tunnel release, post-op three to six months, unless an earlier evaluation is required by the surgeon.

B. Imaging Studies

1. Radiographic Imaging . Not generally required for most CTS diagnoses. However, it may be necessary to rule out other pathology in the cervical spine, shoulder, elbow, wrist or hand. Wrist and elbow radiographs would detect degenerative joint disease, particularly scapholunate dissociation and thumb carpometacarpal abnormalities which occasionally occur with CTS.

2. Magnetic Resonance Imaging (MRI). Considered experimental and not recommended for diagnosis of Carpal Tunnel Syndrome. Trained neuroradiologists have not identified a single MRI parameter that is highly sensitive and specific. MRI is less accurate than standard electrodiagnostic testing, and its use as a diagnostic tool is not recommended.

3. Sonography . This tool has not been sufficiently studied to define its diagnostic performance relative to electrodiagnostic studies. It is not a widely applied test. Sonography may detect synovial thickening in CTS caused by rheumatoid arthritis. It may be useful if space-occupying lesions, such as, lipomas, hemangiomas, fibromas, and ganglion cysts, are suspected. Its routine use in CTS is not recommended.

C. Adjunctive testing . Clinical indications for the use of tests and measurements are predicated on the history and systems review findings, signs observed on physical examination, and information derived from other sources and records.They are not designed to be the definitive indicator of dysfunction.

1. Electromyography . is a generally accepted, well-established procedure. It is indicated when acute and/or chronic neurogenic changes in the thenar eminence are associated with the conduction abnormalities discussed above.

2. Electroneurometer is not recommended as a diagnostic tool because it requires patient participation, cannot distinguish between proximal and distal lesions, and does not have well-validated reference values.

3. Portable Automated Electrodiagnostic. Device measures distal median nerve motor latency and F-wave latency at the wrist and has been tested in one research setting. It performed well in this setting following extensive calibration of the device. Motor nerve latency compared favorably with conventional electrodiagnostic testing, but F-wave latency added little to diagnostic accuracy. It remains an investigational instrument whose performance in a primary care setting is as yet not established, and is not recommended as a substitute for conventional electrodiagnostic testing in clinical decision-making.

4. Quantitative Sensory Testing (QST) may be used as a screening tool in clinical settings pre- and post-operatively. Results of tests and measurements of sensory integrity are integrated with the history and systems review findings and the results of other tests and measures. QST has been divided into two types of testing:

a. Threshold tests measure topognosis, the ability to exactly localize a cutaneous sensation, and pallesthesia, the ability to sense mechanical using vibration discrimination testing (quickly adapting fibers); Semmes-Wienstein monofilament testing (slowly adapting fibers);

b. Density Tests also measure topognosis and pallesthesia using static two-point discrimination (slowly adapting fibers); moving two-point discrimination (quickly adapting fibers).

5. Pinch and Grip Strength Measurements are Not generally accepted as a diagnostic tool for CTS. Strength is defined as the muscle force exerted by a muscle or group of muscles to overcome a resistance under a specific set of circumstances. Pain, the perception of pain secondary to abnormal sensory feedback, and/or the presence of abnormal sensory feedback affecting the sensation of the power used in grip/pinch may cause a decrease in the force exerted and thereby not be a true indicator of strength. When all five handle settings of the dynamometer are used, a bell-shaped curve, reflecting maximum strength at the most comfortable handle setting, should be present. These measures provide a method for quantifying strength that can be used to follow a patient's progress and to assess response to therapy. In the absence of a bell-shaped curve, clinical reassessment is indicated.

6. Laboratory Tests . In one study of carpal tunnel patients seen by specialists, nine percent of patients were diagnosed with diabetes, seven percent with hypothyroidism, and 15 percent with chronic inflammatory disease including spondyloarthropathy, arthritis, and systemic lupus erythematosis. Up to two thirds of the patients were not aware of their concurrent disease. Estimates of the prevalence of hypothyroidism in the general population vary widely, but data collected from the Colorado Thyroid Disease Prevalence Study revealed subclinical hypothyroidism in 8.5 percent of participants not taking thyroid medication. The prevalence of chronic joint symptoms in the Behavioral Risk Factor Surveillance System (BRFSS) from the Centers for Disease Control (CDC) was 12.3 percent. If after two to three weeks, the patient is not improving the physician should strongly consider the following laboratory studies: thyroid function studies, rheumatoid screens, chemical panels, and others, if clinically indicated. Laboratory testing may be required periodically to monitor patients on chronic medications.

D. Special tests are generally well-accepted tests and are performed as part of a skilled assessment of the patients' capacity to return to work, his/her strength capacities, and physical work demand classifications and tolerance.

1. Personality/Psychological/Psychiatric/ Psychosocial Evaluations .

a. These are generally accepted and well-established diagnostic procedures with selective use in the upper extremity population, but have more widespread use in subacute and chronic upper extremity populations. Diagnostic testing procedures may be useful for patients with symptoms of depression, delayed recovery, chronic pain, recurrent painful conditions, disability problems, and for preoperative evaluation. Psychological/psychosocial and measures have been shown to have predictive value for postoperative response, and therefore should be strongly considered for use pre-operatively when the surgeon has concerns about the relationship between symptoms and findings, or when the surgeon is aware of indications of psychological complication or risk factors for psychological complication (e.g. childhood psychological trauma). Psychological testing should provide differentiation between pre-existing conditions versus injury caused psychological conditions, including depression and posttraumatic stress disorder. Psychological testing should incorporate measures that have been shown, empirically, to identify comorbidities or risk factors that are linked to poor outcome or delayed recovery;

b. Formal psychological or psychosocial evaluation should be performed on patients not making expected progress within 6 to 12 weeks following injury and whose subjective symptoms do not correlate with objective signs and test results. In addition to the customary initial exam, the evaluation of the injured worker should specifically address the following areas:

i. employment history;

ii. interpersonal relationships-both social and work;

iii. patient activities;

iv. current perception of the medical system;

v. current perception/attitudes toward employer/job;

vi. results of current treatment;

vii. risk factors and psychological comorbidities that may influence outcome and that may require treatment;

viii. childhood history, including history of childhood psychological trauma, abuse and family history of disability.

c. Personality/psychological/psychosocial evaluations consist of two components, clinical interview and psychological testing. Results should help clinicians with a better understanding of the patient in a number of ways. Thus the evaluation result will determine the need for further psychosocial interventions; and in those cases, Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnosis should be determined and documented. The evaluation should also include examination of both psychological comorbidities and psychological risk factors that are empirically associated with poor outcome and/or delayed recovery. An individual with a Ph.D., Psy.D, or psychiatric M.D./D.O. credentials should perform initial evaluations, which are generally completed within one to two hours. A professional fluent in the primary language of he patient is preferred. When such a provider is not available, services of a professional language interpreter should be provided.

d. Frequency: one-time visit for the clinical interview. If psychometric testing is indicated as a part of the initial evaluation, time for such testing shall be allotted at least, six hours of professional time or whatever is deemed appropriate by the health care professional.

i. Job site evaluation is a comprehensive analysis of the physical, mental and sensory components of a specific job. These components may include, but are not limited to: postural tolerance (static and dynamic); aerobic requirements; range of motion; torque/force; lifting/carrying; cognitive demands; social interactions; visual perceptual; environmental requirements of a job; repetitiveness; and essential functions of a job. Job descriptions provided by the employer are helpful but should not be used as a substitute for direct observation.

(a). Frequency: One time with additional visits as needed for follow-up per job site.

ii. Functional Capacity evaluation is a comprehensive or modified evaluation of the various aspects of function as they relate to the worker's ability to return to work. Areas such as endurance, lifting (dynamic and static), postural tolerance, specific range of motion, coordination and strength, worker habits, employability and financial status, as well as psychosocial aspects of competitive employment may be evaluated. Components of this evaluation may include: musculoskeletal screen; cardiovascular profile/aerobic capacity; coordination; lift/carrying analysis; job-specific activity tolerance; maximum voluntary effort; pain assessment/psychological screening; and non-material and material handling activities.

(a). Frequency: Can be used initially to determine baseline status. Additional evaluations can be performed to monitor and assess progress and aid in determining the endpoint for treatment.

iii. Vocational Assessment : The vocational assessment should provide valuable guidance in the determination of future rehabilitation program goals. It should clarify rehabilitation goals, which optimize both patient motivation and utilization of rehabilitation resources. If prognosis for return to former occupation is determined to be poor, except in the most extenuating circumstances, vocational assessment should be implemented within 3 to 12 months post-injury. Declaration of MMI should not be delayed solely due to lack of attainment of a vocational assessment.

(a). Frequency: One time with additional visits as needed for follow-up

iv. Work Tolerance Screening: is a determination of an individual's tolerance for performing a specific job as based on a job activity or task. It may include a test or procedure to specifically identify and quantify work-relevant cardiovascular, physical fitness and postural tolerance. It may also address ergonomic issues affecting the patient's return-to-work potential. May be used when a full FCE is not indicated.

(a) . Frequency: One time for evaluation. May monitor improvements in strength every three to four weeks up to a total of six evaluations.

AUTHORITY NOTE: Promulgated in accordance with R.S. 23:1203.1.

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