Article

Peripheral neuropathy and is MRI a test for it?

An estimated 30 million Americans suffer from some type of peripheral neuropathy.1 Of that 30 million, 60% of those affected have neuropathy from diabetes. There are a number of other causes of peripheral neuropathy, including alcoholism, autoimmune diseases, infections, tumors and other diseases.2,3

Peripheral neuropathy results from damage to the peripheral nerves. It mainly affects the hands and feet, though it may affect other areas of the body as well. The peripheral nervous system sends information from the central nervous system (that which send information from the brain to the spinal cord) to the rest of your body. Damage to these nerves may result from several different causes, including traumatic injuries, infections, metabolic problems and genetics. In other cases, autonomic nerves may also be affected which provides its own set of symptoms.

People with peripheral neuropathy may have numbness or pain in their extremities. This pain is typically described as stabbing, burning or tingling. Medications can sometimes reduce the pain of peripheral neuropathy, and many people experience improved symptoms over time if the cause is a treatable condition.

Symptoms of peripheral neuropathy2

Typical Peripheral Neuropathy

  • Numbness, prickling or tingling in the hands and feet may appear gradually and spread into the legs and arms at the beginning stage of peripheral neuropathy.
  • Pain that is sharp, jabbing, throbbing, freezing or burning could occur in patients.
  • Patients may be extremely sensitive to touch of any kind, though it is possible that they cannot feel touch to the numb areas.
  • Coordination and balance may be decreased, potentially leading to falls.
  • Patients could have muscle weakness or paralysis if their motor nerves are affected.

Peripheral neuropathy with autonomic nerve involvement

  • Patients with autonomic nerve involvement may experience heat intolerance or altered sweating.
  • Bowel, bladder or digestive problems may also appear in these patients.
  • Issues with the autonomic system may affect blood pressure, resulting in dizziness or lightheadedness.

Risk factors for peripheral neuropathy2,3

  • Diabetes mellitus (also known as simply diabetes)
  • Alcohol abuse
  • Vitamin deficiencies, B vitamins in particular
  • Infections
  • Autoimmune diseases (diseases that cause your immune system to attack your own tissues)
  • Kidney, liver or thyroid disorders
  • Exposure to toxins
  • Repetitive motion, including those performed for certain jobs
  • Family history of neuropathy

Buyers Guide_950x250.jpg

Magnet resonance imaging of peripheral neuropathy

Magnetic resonance imaging (MRI) uses a strong, super-conducting magnet to alter the magnet field around the patient's body. These alterations are controlled by pulse sequences, and the type of sequence controls the type of magnetic resonance images produced. In MR neurography, also known as peripheral nerve imaging, radiographers often need to use suppression techniques to avoid showing the blood vessels, fat and muscle around the nerves as much as possible. This is necessary, because the nerves are small, sometimes less than a millimeter in diameter.4 They also tend to run alongside blood vessels, occasionally causing difficulty differentiating between the two. The anomaly throughout the nervous system may appear as a sort of pinching somewhere along the system.

The most common sequences and techniques used to image peripheral neuropathy are a 3D-volumetric version of STIR imaging and the 2D FSE Dixon sequence.4 These are both available commercially and may have a few different names. However, both types of sequences can be useful for this imaging.

The 3D-volumetric STIR sequence uses parallel imaging to accelerate imaging while providing excellent quality in the images.4 The technique gathers data for a 3D image of the region of interest that may show information about the volumes of different aspects contained, which may reduce the overall number of images needed when compared to those taken with 2D STIR. STIR stands for short T1 inversion recovery. STIR is frequently utilized to suppress fat in magnetic resonance scans. This allows scientists to more easily see the nerves in the body when studying peripheral neuropathy. When put together, these two techniques allow for a high signal-to-noise ratio (SNR), which may help produce more detailed images.

Another method that is helpful in neurography, the 2D FSE Dixon method, utilizes improved water and fat separation to image the regions of interest with a highlight on the nerves themselves.4 The method used creates a 2D image that is acquired using fast spin echo two-point Dixon sequence. The shift from a three-point acquisition to a two-point one helps to reduce the scan time while maintaining the SNR.

The information provided by both the 2D FSE Dixon and 3D-volumetric STIR methods may provide information about a patient's neuropathy. If the information leads to something that can be treated, then the patient may see improvement due to medications prescribed by their doctors. This could help the millions of Americans that have to deal with peripheral neuropathy.

For more information, please read SIGNA Pulse "Update on magnetic resonance neurography."

References

1. "Peripheral Neuropathy Risk Factors + Facts." foundationforpn.org. 2016. Web. 1 May 2019. <https://www.foundationforpn.org/what-is-peripheral-neuropathy/types-risk-factors/>.

2. Mayo Clinic Staff. "Peripheral neuropathy." MayoClinic.org. 9 August 2017. Web. 1 May 2019. <https://www.mayoclinic.org/diseases-conditions/peripheral-neuropathy/symptoms-causes/syc-20352061>.

3. "Peripheral Neuropathy Fact Sheet." NIH.gov. 16 August 2018. Web. 1 May 2019. <https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Peripheral-Neuropathy-Fact-Sheet>.

4. Darryl B. Sneag. "Update on magnetic resonance neurography." SIGNA Pulse. Spring 2018. Web. 6 May 2019. <http://www.gesignapulse.com/signapulse/spring_2018/MobilePagedReplica.action?pm=2&folio=56#pg56>.

Buyers Guide_950x250.jpg