Revenue Cycle Insider

Knowing what the documentation describes is vital to correct code choice.

Patients who need autonomic nerve function testing will need a coder who understands the nuances of these tests.

This requires a grasp of how the nervous system functions, the symptoms that would lead the physician to consider an autonomic test, and the correct codes for your provider’s services.

Check out this primer on coding for autonomic nerve function tests.

Know the Nervous System

When understanding the nervous system, it helps to think of it as a large corporation. The central nervous system (CNS), the brain and spinal cord, serves as corporate headquarters, where information is processed and responses are coordinated. The peripheral nervous system (PNS) functions as the organization’s communication network with nerves that carry information between corporate headquarters and the body’s regional branches, including the muscles, skin and internal organs.   

At the next level of the corporate organizational chart, the PNS divides its workload between two “departments”: the somatic nervous system and the autonomic nervous system (ANS). The somatic department handles sensory information and activities under conscious control. It carries sensory messages to the CNS and delivers instructions to the skeletal muscles for voluntary movements such as typing on a keyboard, walking across a room, or pulling your hand away from a hot stove. The autonomic department manages the body’s essential operations that are necessary for human survival including regulation of heart rate, blood pressure, digestion, sweating, bladder function, and pupil dilation and constriction. Like an administrative department that keeps a corporation running without requiring the chief executive’s attention, the ANS performs most of its work without conscious direction.

When the autonomic “department” does not function properly, the resulting dysfunction is broadly referred to as dysautonomia. Autonomic neuropathy is a type of dysautonomia caused specifically by damage to the nerves controlling involuntary body functions. Continuing down the organizational chart, the ANS divides its responsibilities among three specialized departments:

• The sympathetic nervous system is commonly described as the fight-or-flight system. It prepares the body for physical action, emergencies, or high-stress situations by increasing heart rate, redirecting blood flow away from other organs toward muscles, stimulating sweating, and dilating airways.
• The parasympathetic nervous system is described as the rest-and-digest system. It helps the body recover after a stressor by slowing heart rate, stimulating digestion, and other energy-conserving functions.
• The enteric nervous system, sometimes referred to as the “second brain,” is located within the gastrointestinal (GI) tract and regulates intestinal movement, absorption, and blood flow. This system is somewhat independent but is influenced by both the sympathetic and parasympathetic systems.

Suspected Dysfunction Leads to Autonomic Testing

Autonomic testing is used to identify the presence, severity, and distribution of autonomic dysfunction. The decision generally begins with an office/outpatient evaluation and management (E/M) service (99202 [Office or other outpatient visit for the evaluation and management of a new patient, which requires a medically appropriate history and/or examination and straightforward medical decision making. When using total time on the date of the encounter for code selection, 15 minutes must be met or exceeded.] through 99215 [Office or other outpatient visit for the evaluation and management of an established patient, which requires a medically appropriate history and/or examination and high level of medical decision making. When using total time on the date of the encounter for code selection, 40 minutes must be met or exceeded.]).

After reviewing the patient’s symptoms, history, medications, and examination findings, the physician may order an electrocardiogram (ECG), laboratory studies, or other tests to exclude common causes. The suspected area of dysfunction then determines whether cardiovagal, vasomotor adrenergic, sudomotor, or combined autonomic testing is appropriate.

Stay Informed on Causes and Symptoms of Autonomic Dysfunction

Autonomic dysfunction may result from inherited, autoimmune, metabolic, infectious, neurologic, or traumatic conditions. Examples include familial dysautonomia, hereditary or acquired amyloidosis, diabetes mellitus, Guillain-Barre syndrome, Sjogren syndrome, lupus, Parkinson’s disease, HIV, vitamin B12 deficiency, spinal cord injury, and certain brain or spinal tumors. Autonomic disorders also include conditions such as postural orthostatic tachycardia syndrome (POTS), orthostatic hypotension, and vasovagal syncope.

Symptoms of autonomic dysfunction vary depending on which organs and autonomic pathways are affected. The patient’s symptoms help the physician determine which type of autonomic function testing may be appropriate. Here’s a look at some possible symptoms that might prompt a function test:

• Gastrointestinal: Constipation, diarrhea, nausea, and vomiting
• Bladder and sexual function: Urinary retention and incontinence, increased urinary frequency, and erectile dysfunction
• Cardiovascular and respiratory: Rapid heart rate, blood pressure fluctuations, shortness of breath, and dizziness upon standing  
• Temperature regulation: Excessive or decreased sweating, intolerance to heat or cold, difficulty regulating body temperature
• Visual: Pupils that adjust slowly to light changes

Identify Function When Selecting the Correct Code

Selecting the appropriate autonomic function testing code begins with identifying the function being measured. Here’s a breakdown of the testing codes you’ll be using:

• 95921: (Testing of autonomic nervous system function; cardiovagal innervation (parasympathetic function), including 2 or more of the following: heart rate response to deep breathing with recorded R-R interval, Valsalva ratio, and 30:15 ratio)
  • Function measured: This test examines the body’s control of heart rate during breathing and positional maneuvers.  
  • Test components: Heart-rate changes are recorded during at least two of the following: deep breathing, the Valsalva maneuver, or a move from lying to standing for calculation of the 30:15 ratio.
  • Example patient: A patient with longstanding type 2 diabetes presents with unexplained tachycardia, fatigue, and exercise intolerance. After ruling out common causes, the physician is concerned about diabetic cardiovascular autonomic neuropathy and orders cardiovagal testing.

• 95922: (… vasomotor adrenergic innervation (sympathetic adrenergic function), including beat-to-beat blood pressure and R-R interval changes during Valsalva maneuver and at least 5 minutes of passive tilt)
  • Function measured: This test examines the body’s control of blood pressure during the Valsalva maneuver and passive tilt.
  • Test components: Continuous, beat-to-beat blood pressure and changes in the time between consecutive heartbeats are recorded during the Valsalva maneuver and at least five minutes of passive tilt.
  • Example patient: A 72-year-old presents with recurrent dizziness and weakness that improves after lying down. Orthostatic vital signs demonstrate a decrease in blood pressure without an appropriate response when the patient stands. No other arrhythmia or common cause was found on diagnostic testing. The findings suggest impaired sympathetic regulation of blood pressure and the physician orders vasomotor adrenergic testing.

• 95923: (… sudomotor, including 1 or more of the following: quantitative sudomotor axon reflex test (QSART), silastic sweat imprint, thermoregulatory sweat test, and changes in sympathetic skin potential)
  • Function measured: This test examines the nerves’ ability to control sweating.
  • Test components: One or more testing methods are used to measure sweat production or the skin’s response to stimulation.
  • Example patient: A 52-year-old patient presents with burning pain, tingling, and abnormal sweating in both feet. Examination demonstrates a reduced temperature sensation, but nerve conduction studies are normal. Since nerve conduction studies primarily evaluate larger nerve fibers and the physician suspects a small-fiber neuropathy involving the sympathetic nerves that control sweating, sudomotor testing is ordered to evaluate patient’s sweat response.

• 95924: (… combined parasympathetic and sympathetic adrenergic function testing with at least 5 minutes of passive tilt)
  • Function measured: This test examines the body’s combined control of heart rate and blood pressure, including the passive tilt response.
  • Test components: The provider performs the heart rate and blood pressure testing described in 95921 and 95922 together, including at least five minutes of passive tilt.
  • Example patient: A 28-year-old presents with recurrent dizziness, palpitations and near-syncope that worsen with prolonged standing and improve after lying down. The physician performs a medication review, and an ECG does not demonstrate an arrhythmia. In-office laboratory testing results are all normal. Office vital signs show an increase in heart rate after standing without a decrease in blood pressure. The provider suspects POTS and orders combined testing to evaluate cardiovagal regulation of heart rate and vasomotor adrenergic regulation of blood pressure and vascular tone.

Be Aware of These Potential Coding Issues

Correctly coding autonomic function tests requires more than identifying the function measured; coders must also confirm that all required test components, timing, and reporting requirements are documented.

Remember that 95921 requires at least two qualifying cardiovagal tests, while 95922 requires both the Valsalva maneuver and at least five minutes of passive tilt. A Medicare Administrative Contractor (MAC) may instruct the provider to append modifier 52 (Reduced services) when one of these required components is not performed; therefore, you should review payer-specific guidance.

Also, the code descriptors for 95922 and 95924 require a minimum of five minutes of passive tilt testing. Documentation that does not identify the presence and duration of passive tilt may not support code requirements.

Payers may limit the frequency of autonomic testing. Repeat testing generally requires documentation of a change in the patient’s clinical status, disease progression, or response to treatment. Review applicable payer policies before reporting the service.

Finally, be sure to review bundling rules. For instance, Novitas A54954 explicitly states that you should not report 95924 with 95921 or 95922 for the same testing session.

Dawnelle Sager, CPC, CPMA, CRC, AAPC Approved Instructor,
Senior Consultant, Pinnacle Enterprise Risk Consulting Services