Autonomic Peripheral Neuropathy Coding
Diagnostic coding of this disease is a no-brainer when you understand nervous system anatomy and conditions.
Peripheral neuropathy is a common nervous system disruption that can cause numbness, pain, weakness, and alterations in body functions. A basic understanding of the nervous system and peripheral neuropathies, chart findings to support a neuropathy, and ICD-9-CM and ICD-10-CM categorization of peripheral neuropathies will allow you to:
- Ask physicians the right questions for clarification
- Assure appropriate coding to establish procedural medical necessity
- Assist providers in their documentation practices
- Code more consistently
Basic Structure of
the Nervous System
The nervous system is comprised of the central nervous system and the peripheral nervous system. The central nervous system is divided into the brain and the spinal column. The brain is where the decision-making takes place, based on the sensory nervous input from other areas of the body. Nervous tissue or pathways outside of the central nervous system are part of the peripheral nervous system.
The peripheral nervous system is also divided into two parts: the autonomic and somatic systems. The autonomic nervous system is controlled “automatically” by the brain’s outgoing messages, in response to incoming sensory information. For example, the viscera (heart, lungs, stomach, and intestines) and other organs, such as the eyes and bladder, are not within the complete, conscious control of the individual. These organs are primarily controlled by the brain’s parasympathetic (relaxing) or sympathetic (excitation) messages.
The organs of the somatic nervous system, or musculoskeletal system, allow for a high level of conscious control. For example, if your hand were to touch a hot stove, the sensory input to your brain would send the action message to your hand to pull away; however, you would have some control over whether you moved your hand.
Regardless of whether you are discussing the central or peripheral nervous system, the basic cell remains the same. The nerve cell consists of a cell body, where sensory information is translated into a motor command. Numerous dendrites carry the sensory information to the cell body. A single axon moves the motor impulse from the cell body to the axon terminals, which end at an internal organ, skeletal muscle(s), or another group of nerve dendrites. The axon is covered in myelin sheaths, which help to protect it against damage. Destruction of the myelin sheath leaves the longer axon vulnerable to injury, resulting in the neuropathies.
The Origin of Neuropathy
Many situations can cause a neuropathic condition. The most common medical condition to cause peripheral neuropathy is diabetes mellitus. The hyperglycemic state can cause direct injury to parts of the nerve cell, as well as indirect injury caused by lack of circulation (and subsequent nutrient deprivation) to the cells. Other medical conditions, such as HIV, kidney disorders, hormonal imbalances, and cancers, also can damage nerve cells. Heredity can play a role, as can traumatic situations such as a crush injury or fractured bone, which can result in compression, stretching, or severing of the nerve cell, leading to a neuropathic condition.
Interpreting Neuropathy Documentation
When reviewing your practice’s medical records for support of a peripheral neuropathy diagnosis, look for indications of the cause of nerve damage, such as diseases or traumas, to help determine if peripheral neuropathy exists, and which type. Symptoms reported by the patient, or signs the provider finds during the exam, can support a diagnosis of peripheral neuropathy and assist in determining if the correct type of neuropathy is documented as the final diagnosis.
Autonomic nerve damage will manifest in several ways, such as an inability to sweat, loss of bowel or bladder control, dizziness, and digestive problems. Somatic peripheral nerve damage (either sensory or motor) could result in complaints of numbness, loss of position, painful cramps, muscle weakness or loss, and changes in skin, hair, and nails.
Although you would not choose the correct diagnosis code from the documented signs and symptoms, you should query the provider if the final diagnosis is not supported by the remainder of the medical record documentation. For example, if the provider were to document peripheral autonomic neuropathy, but the symptomatology lists numbness and tingling of the hands and feet, be sure to clarify whether there truly is an autonomic problem, or if the problem lies with the somatic nervous system.
Diagnosis Code Assignment
The codes for peripheral neuropathy diagnoses can be found in Chapter 6: Diseases of Nervous System and Sense Organs (320-389) of the ICD-9-CM code book. You may find the terminology for the peripheral neuropathies does not mirror the true clinical conditions, which can make it difficult to assign codes.
Somatic (the peripheral system that innervates the muscular skeletal system) is not found within the alphabetical index of neuropathies. Luckily, clinicians do not often use the term “somatic” when describing neuropathies. Rather, a somatic neuropathy affecting the muscular skeletal system is termed simply in medical records as “peripheral neuropathy.” The alphabetical index of the ICD-9-CM code book will direct you to use codes from Chapter 6, under the category Disorders of the Peripheral Nervous System (350-359), for these muscular skeletal system neuropathies.
You also may be faced with the decision of a mono (one) or a poly (more than one) peripheral nerve issue. Unless the provider clearly states this in the record, you may have difficulty determining which category of neuropathies to use. The alphabetical index of the ICD-9-CM code book refers you to “polyneuropathy,” and the default code of 356.9 Unspecified hereditary or idiopathic peripheral neuropathy, when the term “neuropathy” is used. If the provider does not further clarify, or the documentation does not raise further issues, you may use a peripheral polyneuropathy code.
Peripheral autonomic neuropathies can be found in the alphabetical index and have a category in the tabular list; however, the category for the peripheral autonomic neuropathies is found within the central nervous system section, rather than the peripheral nervous system. Specifically, the peripheral autonomic nerve disorders are found within category 337 Disorders of the autonomic nervous system, which are located in ICD-9-CM, Chapter 6, under Hereditary and Degenerative Diseases of the Central Nervous System (330-337). For example, a diagnosis of peripheral autonomic neuropathy would be coded with 337.00 Idiopathic peripheral autonomic neuropathy, unspecified.
Logically, this may seem appropriate because the functions of the autonomic nervous system are largely outside of the control of the individual, as are the functions of the central nervous system. But clinically, it’s not a clear match of the system’s anatomy and physiology.
Determine Underlying Cause
After the correct part of the nervous system is identified, you must also determine from the documentation if there is an underlying cause for the neuropathy. For the autonomic nervous system, the idiopathic and hereditary neuropathies are found in category 337, along with those caused by underlying conditions (such as diabetes). For example, if a patient is diagnosed with diabetic peripheral autonomic neuropathy, along with the appropriate code from category 250 Diabetes mellitus, you would also report 337.1 Peripheral autonomic neuropathy in disorders classified elsewhere. In the case of the somatic nervous system, the hereditary and idiopathic peripheral neuropathies are found in category 356 Hereditary and idiopathic peripheral neuropathy, while those caused by underlying conditions (e.g., diabetes) can be found in category 357 Inflammatory and toxic neuropathy. Diabetic peripheral neuropathy is coded with the appropriate code from category 250 and 357.2 Polyneuropathy in diabetes.
Code It Using ICD-10-CM
ICD-10-CM coding of peripheral neuropathies follows a similar pattern as ICD-9-CM, with a few changes. Many neuropathies caused by other conditions will be listed with the other conditions as combination codes. For example, diabetic neuropathies are now combination codes within the diabetic code categories (I8 through I13), rather than within the nervous system chapter. Coding these conditions requires one code, rather than separate diabetes and neuropathy codes. The aforementioned diabetic peripheral autonomic neuropathy would now only require one code, E11.43 Type 2 diabetes mellitus with diabetic autonomic (poly)neuropathy. Likewise, the aforementioned diabetic peripheral neuropathy would also only require one code, E11.42 Type 2 diabetes mellitus with diabetic polyneuropathy. (Note: The category of diabetes in ICD-10-CM depends on the documented type of diabetes. In this example, we default to E11 Type 2 diabetes mellitus, as directed by ICD-10-CM, because the type of diabetes is not documented as type 1, type 2, or secondary.)
In ICD-10-CM, peripheral autonomic neuropathies codes are found within category G90 Disorders of autonomic nervous system, in the section titled “Other disorders of the nervous system.” And our earlier diagnosis of peripheral autonomic neuropathy would be coded G90.09 Other idiopathic peripheral autonomic neuropathy.
Understanding the Basics Is Key
The nervous system can be fascinating, and a basic understanding of it is an important factor in determining which codes represent the documented conditions. You can use clues from several documentation areas to choose the right code, or to determine whether you should query the provider. Having a clear understanding of anatomy and conditions will help you to achieve consistent coding and set a standard of professionalism for medical coders.
Denise M. Hull, JD, MHA, BSN, CPC, is a provider performance improvement consultant with Excellus BCBS in Rochester, N.Y. She works with hospitals on pay-for-performance quality programs to assist in improving the safety of medical care and driving improvements in quality healthcare. Hull also has worked as a Medicare Risk Advantage coder with the organization. Her previous professional experiences included 25 years of clinical nursing experience, primarily in the emergency department setting. She is a member of the Rochester, N.Y., local chapter.