Is it peripheral neuropathy?

Learn the right way to diagnose this painful condition.

The onset of peripheral neuropathy can be so sudden and severe as to be a life-changing event for a hospitalized patient.

“I have had a handful of cases that were dramatic,” said Rachel Thompson, ACP Member, assistant professor of general internal medicine at the University of Washington in Seattle. “It is not something you encounter frequently, but when you do, it is something that you do not forget.”

Photo by Thinkstock
Photo by Thinkstock.

Peripheral neuropathies are common, according to Dr. Thompson, occurring in up to 10% of the general population.

About 5% to 8% of people over age 55 have a polyneuropathy, according to Ted M. Burns, MD, associate professor of neurology at the University of Virginia, Charlottesville. That same percentage is probably found in a hospitalized population, he said.

A hospitalist who recognizes the symptoms of peripheral neuropathy and understands their significance can play a critical role in a patient's quality of life and, in some cases, survival, experts say. “We are in a position to get patients the help they need on the early side,” when the condition may still be reversible, Dr. Thompson said.

Acute peripheral neuropathy

Clinicians may see acute or chronic peripheral neuropathy in the hospital, experts said. An acute onset is “an entirely different beast than a chronic neuropathy with a gradual onset,” Dr. Burns said. Acute onset could indicate Guillain-Barré syndrome, vasculitis, toxicity, or a critical illness polyneuropathy. It often manifests as decreased sensation; weakness; decreased reflexes; severe pain described as burning, freezing, electric shocks and/or throbbing; numbness; paralysis; difficulty weaning from a ventilator; and other symptoms. It can develop suddenly or over days to weeks.

Several conditions can place patients at risk for acute neuropathy in the hospital. For example, some patients with diabetes can develop acute neuropathy, particularly when they are being treated in the ICU, noted Milind J. Kothari, DO, professor of neurology at Penn State University College of Medicine in Hershey, Pa.

“These patients may have some severe pneumonia or sepsis that has taken them to the ICU,” he said. “In the ICU, their underlying neuropathy can then manifest itself as prolonged weakness….They may have trouble weaning off the ventilator because their nerves and muscles aren't operating correctly. They develop a critical illness neuropathy or worsening of their ongoing diabetic neuropathy.”

Even for patients without diabetes, critical illness polyneuropathy can develop in the ICU, the result of sepsis-related damage to the peripheral nerves and muscles. According to Dr. Kothari, critical illness polyneuropathy is characterized by motor weakness, muscle atrophy and difficulty weaning from ventilator support.

Other factors that increase the risk for acute neuropathies are cancer and treatment with certain chemotherapy agents, toxins, paraneoplastic syndromes, diphtheria, rheumatologic conditions, certain HIV medications, and alcohol use.

Start with a checklist

Drs. Thompson and Burns recommend that hospitalists employ a quick checklist for inpatient, acute peripheral neuropathy.

“As hospitalists, we can focus on being thorough with our patients—evaluate all symptoms and look for associated symptoms that are problematic,” said Dr. Thompson.

The list should include some variation of the following diagnostic questions:

  • When did the symptoms first begin?
  • Where are the symptoms distributed?
  • What is the pattern?
  • Is the pathology axonal, demyelinating, or mixed?

A physical exam should help determine the distribution of the neuropathy, such as whether the symptoms are symmetric and follow a stocking-glove pattern, or whether they occur in an ascending symmetric pattern that is typical of Guillain-Barré syndrome.

The physical exam should also help the hospitalist answer the following questions:

  • Is a single nerve involved, indicating a mononeuropathy that is commonly associated with trauma or ischemia?
  • Are multiple nerves involved, as in a polyneuropathy that could be consistent with vasculitis or toxicity?
  • Is the distribution asymmetric and involving several separate nerves–a mononeuropathy multiplex that could be associated with ischemia, vascular steal, and/or nerve compression and caused by trauma, lymphoma or vasculitis?

Sometimes symptoms of polyneuropathy can mimic a spinal cord problem, Dr. Burns said. “Consider the possibility of cervical myelopathy or myelitis as responsible for the symptoms. In polyneuropathy the reflexes are going to be reduced or absent; in the spinal cord problem, they will usually be increased. So tapping on reflexes will help, and sometimes imaging is indicated,” he said.

Testing, in the right order

Electrodiagnostic testing can confirm the distribution of nerve involvement and clarify whether the neuropathy is demyelinating or axonal or a combination of the two. The results of the sensory nerve conduction tests should be reviewed before you order “shotgun labs,” Dr. Thompson advised.

“The electrodiagnostic test can tell you whether you have the right location and can differentiate whether this is or is not a peripheral neuropathy or whether it is a peripheral spinal stenosis or something else that is causing the symptoms,” she said. “This then will help clarify which labs you need and where you would go from there,” she said.

Follow-up testing may include ultrasound, magnetic resonance imaging (MRI), computed tomography-positron emission tomography (CT-PET) and nerve biopsy. Dr. Thompson, in an article published in the July/August 2009 issue of the Journal of Hospital Medicine, said that a nerve biopsy should be reserved for suspected vasculitis, sarcoidosis, lymphoma, leprosy or amyloidosis.

Given the complexity of diagnosis and the potential of acute neuropathy to threaten life and limb, these patients generally merit a neurology consultation, the experts advised. If the neuropathy is associated with respiratory symptoms or signs, that consult should be urgent, Dr. Thompson said.

Chronic neuropathy

Hospitalists are also in a good position to evaluate worsening or previously unrecognized and untreated symptoms of chronic neuropathy, which can usually be referred to an outpatient setting for management and treatment.

Some peripheral neuropathy progresses slowly and becomes apparent when the patient is bedridden for another condition. Mark Bromberg, MD, professor of neurology at the University of Utah, said that such a patient may have difficulty getting out of bed after a four- or five-day period in the hospital and may even have some atrophy.

In this setting, diabetes should be considered as a cause. “The patient may either have known diabetes or have been diagnosed years before with prediabetes. These patients can easily have a neuropathy from diabetes that was either unrecognized or was an underlying neuropathy that became symptomatic in the hospital,” Dr. Bromberg said.

According to Dr. Thompson, the symmetric polyneuropathies associated with diabetes are also similar to alcohol-induced neuropathies. When a hospitalist identifies this pattern and confirms the comorbid condition of diabetes or alcohol use, further workup may be needed (but, again, can be referred to an outpatient setting).

A hospitalized patient may also mention symptoms of neuropathy that he or she had not previously disclosed to a primary care physician. “One of the luxuries of our profession is that we can uncover things that patients have not had time to discuss in a primary care setting. Some patients have tingling or burning feet or weakness in an arm, but they have not thought it was important enough to bring up with their doctor,” said Dr. Thompson.

“The hospitalist has more potential chances for encounters or frequency of encounters, providing more opportunities to recognize and manage symptoms that can affect a patient's quality of life,” she said.