Thursday, August 27, 2009

Median Nerve H-reflex and Pain Diagnosis

Research Published - October 2009 at National Meeting
Below is a summary of our research presented at the 20th Annual Clinical Meeting of the American Academy of Pain Management, held in Phoenix, Arizona, October 8-11, 2009. The study was done jointly by Dr. Larison and Dr. Campa, over the last two years. Dr. Larison was on-site to present our findings.

The sharing of our research will hopefully assist other clinicians to more accurately, and in a more timely fashion, isolate and treat the underlying cause of a patient's pain, in those individuals who present with neck and upper extremity pain.

Tom C. Larison, DC
John A. Campa III, MD
August 27, 2009

Median Nerve H-reflex and Pain Diagnosis

Patients with neck and upper extremity pain and underlying multilevel cervical disc disease present special problems in the diagnosis and management of the primary pain generator. Lesions are routinely diagnosed on x-ray, CT and MRI as degenerative, and not usually considered as a legitimate source for the patient's pain complaints, resulting in undertreatment and delay in improving the baseline pain control.

The Flexor Carpi Radialis Median nerve H-reflex study (FCR-HR), in its assessment of the functional impact of these lesions, would help clinicians resolve the primary source of the patient's pain, and permit a focused and directed approach to more definitive management. It is particularly suited for this task, as it is mediated by the C6 and C7 nerve roots, which exit the cervical spine at the C5-6 and C6-7 levels, respectively. Hence, a delayed response would indicate the presence of a lesion at either level.

While the literature describes the use of HR in the diagnosis of neuropathy and radiculopathy, we believe our study is the first to address its usefulness in assessing cervical degenerative discs as potential pain generators.

To assess the diagnostic usefulness of the FCR-HR in patients with neck and upper extremity pain and C5-6, C6-7 cervical disc disease.

An 18-month retrospective chart review was performed of patients with neck and upper extremity pain, who underwent EMG-NCV studies, where Median nerve neuropathy was excluded, and FCR-HR was abnormal. Results were correlated with XR, CT, MRI, and clinical findings.

62 cases underwent EMG for neck and extremity pain; Abnormal HR: 29/62 (47%); Abnormal HR and correlating xray/CT/MR (C5-6/C6-7): 12/29 (41%); Abnormal HR and C6, C7 correlating EMG paraspinals: 10/29 (34%); Abnormal HR and adjacent disc disease: 5/29 (17%); Correlating lesions: DDD, disc bulge, protrusion, extrusion, listhesis, foraminal narrowing, cord impingement, thecal sac effacement, osteophytic ridging, Modic Type I, central canal stenosis.

The FCR-HR is a useful diagnostic tool in the assessment of C5-6, C6-7 cervical disc disease as a primary pain generator. We recommend its routine use in the evaluation of patients with neck and upper extremity pain, who present with multilevel cervical disc disease.

1. Jabre, JF. Surface recording of the H-reflex of the flexor carpi radialis. Muscle Nerve. 1981;4:435.
2. Sethi, RK, Thompson, LL. The Electromyographer’s Handbook. 2nd ed. Boston, MA/Toronto, ON: Little, Brown and Company; 1989; 107.
3. Knikou, M. The H-reflex as a probe: pathways and pitfalls. J Neurosci Methods. 2008;171(1):1-12.
4. Delagi, EF, Perotto, A. Anatomic Guide for the Electromyographer. 2nd ed. Springfield, IL: Charles C. Thomas; 1980; 46.

Normal FCR-H-Refelx

Abnormal FCR-H-Refelx

Median Nerve H-Reflex Anatomy and Physiology

FCR-HR Technique
• Recording electrode - 1/3 distance between medial epicondyle - humerus and radial styloid.

• Reference electrode - Over radial styloid.

• Ground - Between stimulation site and recording electrode.

• Stimulation site - Median nerve at elbow.

Tom C. Larison, DC
Pain Diagnosis Consultants, LLC
August 27, 2009