The employer and insurer appeal from the compensation judge’s decision approving the employee’s request for a repeat cervical MRI scan.  We affirm.

Robert Lange sustained a work-related injury on February 27, 2009, while employed by Resource Recovery Technologies at a recycling plant.  The first report of injury and initial medical records indicate that the employee slipped on icy steps at the plant and fell backwards, striking his head.  The employer and its insurer accepted liability for the injury.

Mr. Lange’s initial symptoms after his work injury were neck pain and headaches.  He received chiropractic adjustments for about six weeks with no particular improvement.  A CT scan of the head taken in March 2009 was negative except for showing reversal of normal lordotic curvature.

In April 2009, Mr. Lange began treating with Dr. David DeGear at the New Richmond Clinic with complaints of headaches and neck pain.  Dr. DeGear has been the employee’s primary treating physician since that time and has made a number of referrals to specialists for treatment options and has also prescribed physical therapy, medication, and restrictions in physical activity.  In June 2009, Mr. Lange had an MRI scan of the cervical spine at the direction of Dr. DeGear.  It was read as negative except for mild straightening of the cervical lordotic alignment.

Later in June 2009, when Mr. Lange saw a physician at St. Croix Orthopaedics, it was noted that, while he continued to have neck pain, his main concern was “severe dizziness and positional vertigo.”  A neurological consultation was recommended at that time.  The neurological consultation was done in July 2009 by Dr. John Floberg who assessed post-concussion syndrome.  A brain MRI scan done on July 8 was interpreted as normal.

Later in July, Mr. Lange was evaluated at the National Dizzy & Balance Center where the conclusion was that his condition was “cervicogenic dizziness.”  No further testing or treatment was done at that facility.  The employee’s QRC arranged for an orthopedic consultation where a cervical CT scan was ordered and done on August 26, 2009.  The orthopedist, Dr. Michael Smith, concluded the CT scan was basically normal and advised Mr. Lange that no further treatment was needed for his neck.

Mr. Lange had a number of physical therapy sessions at Physicians Neck and Back Clinic in August and September 2009, but stopped treatment there because he felt it was not helping his condition.  Dr. DeGear also recommended therapy at Courage Center.  An initial evaluation was done at that facility, but there are no records of any treatment there.

The employee was seen for an independent medical examination in April 2010 by Dr. John Dowdle.  Dr. Dowdle concluded that Mr. Lange had sustained a contusion of the upper cervical spine that possibly was causing facet inflammation and resulting in the employee’s headaches.  Nevertheless, Dr. Dowdle stated that Mr. Lange was at maximum medical improvement, had no permanent partial disability, needed no work restrictions, and needed no “additional passive care.”

The employee continued to see Dr. DeGear on an intermittent basis, and, in early 2013, Dr. DeGear referred Mr. Lange to Dr. Rita Richardson, a neurologist at Westfields Hospital.  At that appointment on April 16, 2013, the employee noted he continued to have dizziness and headaches, as well as what he described as neck pain at a level from 5 to 8 on a 10-point scale, along with pain into his left shoulder and episodic left arm tingling.  Dr. Richardson stated, “[w]ith his injury, ligamentous changes cause upper cord involvement could cause vertigo.  Additionally he does c/o of episodic left arm tingling.”  Dr. Richardson prescribed a cervical MRI scan.

The employee filed a medical request in July 2013 seeking approval of the cervical MRI scan recommended by Dr. Richardson.  Ultimately, the employee’s request was heard at a formal hearing before Compensation Judge Rolf Hagen on October 16, 2013.  In his findings and order issued November 14, 2013, the compensation judge ordered the employer and insurer to pay for the requested MRI scan.  The employer and insurer have appealed.

The issues at the hearing were whether the repeat cervical MRI scan recommended by Dr. Richardson was causally related to the work injury and whether the MRI scan was reasonable and necessary treatment.

In their appeal, the employer and insurer focus on the credibility of the employee.  They point out that in the first report of injury and in medical records before the appointment with Dr. Richardson, the employee described his injury as having occurred when he slipped on icy steps and hit his head.  However, the employee told Dr. Richardson that he had been injured when tires fell on his head and neck, the first time he had provided that history.  The appellants contend that this “incorrect” history establishes that the employee’s complaints to Dr. Richardson were not related to the February 27, 2009, work injury and that there is no basis for ordering the employer and insurer to pay for the repeat MRI scan.

The employee was cross-examined at the hearing by counsel on the discrepancy in his medical history.  The compensation judge accepted the employee’s testimony at the hearing that his injury occurred when tires fell from a stack and struck him.  The compensation judge concluded that the employee’s testimony on this point was credible.  This court will generally defer to a compensation judge’s credibility determination.  Murphy v. Anoka Drug & Gifts, 63 W.C.D. 158 (W.C.C.A. 2002); McLafferty v. RS Eden, WC07-218 (W.C.C.A. Feb. 4, 2008).  Assessment of witnesses’ credibility is a unique function of the trier of fact.  Brennan v. Joseph G. Brennan, M.D., P.A., 425 N.W.2d 837, 41 W.C.D. 79 (Minn. 1988).  We see no basis to reverse the compensation judge’s finding on this question.

Substantial evidence in the form of the employee’s credible testimony and the medical records support the compensation judge’s determination that the proposed medical testing is related to the employee’s work injury in February 2009.

The second issue at the hearing was whether the proposed cervical MRI scan is reasonable and necessary care for the employee’s work injury.  The employer and insurer make no argument on this issue on appeal other than contending that Dr. Richardson’s recommendation did not comply with the requirement of the treatment parameters.  Although not specifically cited, assumedly the reference is to Minn. R. 5221.6100, dealing with the parameters for medical imaging.

Although the employer and insurer admitted the employee had sustained a work injury on February 27, 2009, liability for the proposed treatment was denied.  (T.13-14)  As a result, the treatment parameters do not apply in the present case.  Mattson v. Northwest Airlines, slip op. (W.C.C.A. Nov. 29, 1999); Armstrong v. RJ Sport & Cycle, 71 W.C.D. 235 (W.C.C.A. 2011).

In his memorandum, the compensation judge set out the evidence he found persuasive in concluding that the proposed testing was reasonable and necessary.  He noted that the employee’s care had been extensive and conservative but had not been effective in resolving or reducing the employee’s symptoms.  Further, the employee’s symptoms appear to have changed with the employee testifying that he had more spasms in his neck, shoulder pain, and numbness in his arm.  Dr. Richardson stated in her chart note that the employee’s symptoms could be due to “upper cord involvement,” necessitating a cervical MRI scan.

We conclude substantial evidence supports the compensation judge’s determination.  The compensation judge’s decision is affirmed.