Discrepancies Between MRI and EMG Results in Back Pain

MRI examination shows a herniation at L5-S1 without nerve compression, but the electromyography (EMG) results indicate..?

Hello Dr.
Chang,
In May 2014, I was hospitalized due to a persistent high fever.
Despite several days of antibiotic treatment, my condition did not improve.
During the examination, the doctor noticed that I could not bring my chin close to my neck, and there were abnormalities during the leg lift test.
I was advised to undergo a lumbar puncture to check for meningitis.
The results indicated aseptic meningitis.
A few days before my discharge, I began to experience leg numbness while walking, accompanied by severe pain that worsened over time.
The doctor arranged a consultation with a neurosurgeon and scheduled an MRI.
On the day of my discharge, I consulted the neurosurgeon regarding the MRI report, who diagnosed an L5-S1 herniation with nerve compression and recommended high-frequency thermal coagulation to alleviate the pain.
I underwent the procedure that afternoon, and about a week later, I noticed that the pain had subsided and I could walk normally.
However, in December 2015, I began to experience pain and difficulty walking again.
I consulted another neurosurgeon at the same hospital, who reviewed the MRI from May and performed a knee reflex test.
He suggested that everything seemed fine and recommended another MRI.
After reviewing the December MRI, he concluded that it looked acceptable and prescribed pain relief, muscle relaxants, and vitamin B12, advising me to undergo traction rehabilitation.
I completed three months of rehabilitation and felt some improvement by March 2016.
The rehabilitation physician also indicated that further rehabilitation was unnecessary.
However, by the end of July, due to work-related fatigue, I experienced a recurrence of walking difficulties and increased limping.
I initially returned to the rehabilitation department for traction therapy, receiving pain relief injections four to five times and undergoing traction for nearly two weeks, but I felt no improvement and the pain intensified, with severe weakness and numbness in my right leg.
I then consulted Dr.
Huang at the Neurosurgery Department of Taipei Veterans General Hospital.
He reviewed the December 2015 MRI and examined me while lying down.
He believed that the lumbar MRI appeared normal and should not cause such leg numbness.
After waiting over a month for further tests, and due to my unbearable pain, I sought a consultation with Dr.
Niu at Chang Gung Memorial Hospital.
He reviewed the same MRI and ordered two X-rays, stating that while there was a herniation, it did not compress the nerve.
The X-rays revealed an old injury with a fracture (I had previously fallen from a height of about two stories, landing on my buttocks and injuring my toes).
Dr.
Niu did not prescribe any medication and advised me to swim, indicating that further rehabilitation traction was unnecessary.
I was taken aback, considering the high-frequency thermal coagulation I had previously undergone for nerve compression.
That same day, I sought a second opinion from the neurosurgery department at Taipei Medical University Hospital in Zhongyonghe.
The doctor initially stated that there was no nerve compression, but upon viewing the MRI from different angles, he suggested that it appeared as if there might be pressure at the exit point.
I requested a new lumbar MRI, which was conducted in August 2016.
The results showed L5-S1 herniation without nerve compression.
A month later, I underwent a cervical MRI because this physician had been prescribing an expensive medication, "Xianyoujie," and I had tried intravenous injections and steroids directly into my back, but the pain and numbness persisted.
The cervical MRI results were interpreted by another neurosurgeon, Dr.
Lin, who stated that the cervical MRI looked excellent with no herniation, while the lumbar MRI also indicated L5-S1 herniation without nerve compression.
Since my primary symptoms were low back pain and leg numbness, he further examined the lumbar region and suspected that a possible herpes zoster infection might be causing my walking difficulties and leg numbness.
That day, he adjusted my medication, keeping only "Tong'an" and "Zan'an" while adding Pregabalin, and arranged for an electromyography (EMG) test.
He mentioned that the worst-case scenario would involve a procedure to clean out the area.
Today, after completing the EMG, I asked the rehabilitation physician who performed the test, and she indicated that there was nerve compression and that it seemed to have been present for a long time.
She could not disclose detailed information about the situation or treatment.
I would like to ask Dr.
Chang whether it is common in clinical practice for patients like me to have normal lumbar MRIs but EMGs indicating nerve compression.
Should I rely more on the EMG results or the MRI findings? I am truly in unbearable pain and sincerely seek your guidance.
Thank you.

Xiao Weiwei, 30~39 year old female. Ask Date: 2016/09/13

Dr. Zhang Junwei reply Neurosurgery

In clinical practice, it is uncommon to find normal lumbar MRI results while electromyography indicates nerve compression.
It seems that the cause of your pain is not entirely clear; why not consider trying high-frequency thermal coagulation therapy again?

Reply Date: 2016/09/13

More Info

Understanding discrepancies between MRI and EMG results in back pain can be quite complex, especially given the nuances of spinal conditions and nerve function. Your situation, as described, highlights a common clinical challenge where imaging studies and electrophysiological tests provide differing insights into the underlying pathology.

MRI vs. EMG: Key Differences
MRI (Magnetic Resonance Imaging) is a powerful imaging tool that provides detailed images of soft tissues, including intervertebral discs, spinal cord, and nerve roots. It is particularly useful for identifying structural abnormalities such as herniated discs, spinal stenosis, and other degenerative changes. However, MRI may not always correlate perfectly with a patient's symptoms or nerve function. For instance, a herniated disc may appear on MRI without causing significant nerve compression, leading to a lack of symptoms.

EMG (Electromyography), on the other hand, assesses the electrical activity of muscles and the function of the nerves that control them. It can detect nerve damage or dysfunction, even when structural abnormalities are not evident on MRI. EMG can reveal issues such as nerve root compression or neuropathy that may not be visible on imaging studies.

Clinical Implications
In your case, the MRI indicated an L5-S1 disc herniation but did not show significant nerve compression. However, the EMG suggested that there is nerve compression affecting the nerve roots, which aligns with your symptoms of leg weakness and numbness. This discrepancy can occur for several reasons:
1. Variability in Nerve Compression: Nerve roots can be intermittently compressed due to factors like inflammation, muscle spasms, or positional changes that may not be captured in a static MRI image.

2. Chronic Changes: Over time, chronic conditions can lead to changes in nerve function that may not correlate with the current structural findings on MRI. For example, a previously compressed nerve may have residual effects even after the structural issue has resolved.

3. Technical Limitations: MRI may not always capture the full extent of nerve root involvement, especially if the compression is subtle or occurs in a dynamic manner.

Recommendations
Given the complexity of your symptoms and the discrepancies between the MRI and EMG findings, here are some recommendations:
1. Consultation with Specialists: It may be beneficial to have a multidisciplinary approach involving neurologists, orthopedic surgeons, and pain management specialists. Each can provide insights based on their expertise.

2. Consider Further Imaging: If symptoms persist, additional imaging studies such as a CT myelogram or repeat MRI with different protocols may provide more clarity on nerve root involvement.

3. Focus on Symptoms: While both MRI and EMG are important diagnostic tools, your symptoms should guide treatment decisions. If EMG indicates nerve involvement, treatments aimed at alleviating nerve compression, such as physical therapy, medications, or possibly surgical intervention, may be warranted.

4. Physical Therapy: Engaging in a structured physical therapy program can help strengthen the muscles around the spine, improve flexibility, and potentially alleviate some of the pressure on the nerve roots.

5. Pain Management: Consider discussing pain management options with your healthcare provider, including medications, injections, or alternative therapies that may help manage your symptoms while you explore further diagnostic options.

Conclusion
In conclusion, the discrepancies between MRI and EMG results in back pain are not uncommon and can arise from various factors. It is essential to consider both the imaging findings and the clinical symptoms when determining the best course of action. Collaboration with healthcare professionals who can interpret these results in the context of your overall health and symptoms will be crucial in managing your condition effectively. Your pain and discomfort are valid, and seeking comprehensive care is the best approach to finding relief.

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