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Coding for Patients with Neurologic Complications of Systemic Disease in the Era of Electronic Health Records

Weathers, Allison L. MD; Premetz, Amy MS, RHIA

doi: 10.1212/01.CON.0000450976.29817.1d
Practice Issues

Address correspondence to Dr Allison Weathers, 1725 West Harrison Street, Suite 1106, Chicago, IL 60612,

Relationship Disclosure: Dr Weathers has received honoraria and travel reimbursement for speaking engagements and workgroup and committee participation from the AAN and grand rounds and lectures given for the Los Angeles Neurological Society, Wake Forest Neurology Department, and the North Carolina Neurological Society. Ms Premetz reports no disclosures.

Unlabeled Use of Products/Investigational Use Disclosure: Dr Weathers and Ms Premetz report no disclosures.

Accurate coding is an important function of neurologic practice. This contribution to CONTINUUM is part of an ongoing series that presents helpful coding information along with examples related to the issue topic. Tips for diagnosis coding, Evaluation and Management coding, procedure coding, or a combination are presented, depending on which is most useful for the subject area of the issue.

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A recent survey by the AAN found that over 80% of neurologists are now using an electronic health record (EHR) in their practice.1 EHRs have evolved substantially over the past several years, with many vendors now offering fully integrated clinical and practice management systems. These integrated systems are able to provide unprecedented support and guidance to clinicians in their documentation and coding. If used incorrectly or carelessly, however, EHRs may result in poor documentation and erroneous coding. This in turn may lead to rejected charges and even accusations of fraud. In addition to discussing the issues that arise with coding the neurologic manifestations of systemic disease, this article will highlight some of the potential advantages and pitfalls of EHR-assisted documentation and coding.

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The International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes are currently used for the reporting of diagnoses. The transition to the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) was to take place on October 1, 2014, but this has been delayed by legislation, likely to October 1, 2015; however, final interpretation is pending. To support coding currently, an EHR should have at a minimum either a built-in database of ICD-9-CM codes or the capability to integrate with an external complete database of codes, such as the one published jointly by the US Centers for Medicare & Medicaid Services (CMS) and the National Center for Health Statistics. While the inclusion of this functionality should not be assumed, most vendors are now offering it in order to obtain certification under the Office of the National Coordinator for Health Information Technology Certification Program.2 This certification signifies that the EHR meets the standards and criteria required by the Medicare and Medicaid EHR Incentive Program (“Meaningful Use”). EHRs can be designed so that these databases are searchable alphabetically and numerically and easily accessible from various activities in the EHR, including the problem list and visit diagnosis fields.

ICD-9-CM will eventually be replaced by the ICD-10-CM. The new ICD-10-CM codes allow for physicians and health care organizations to report higher levels of specificity and clinical detail.3 Changes in the ICD-10-CM will significantly impact how codes are assigned and the documentation required to support their use. Providers who are considering the purchase of a new EHR or planning to upgrade their current system during the transition period should thoroughly evaluate a potential vendor’s readiness for this transition. The CMS website includes extensive resources to help practices prepare for ICD-10-CM, including questions to ask EHR vendors.4

Beyond providing access to an easily searchable and comprehensive database, EHRs can facilitate coding in a number of other ways. Diagnosis codes and Evaluation and Management (E/M) codes may be captured electronically at the time of service, preventing delays in charge submission and billing. Some EHRs require that the visit diagnoses (or appropriate diagnoses codes) and E/M codes be entered prior to allowing a chart to be electronically closed. Warnings can be configured to alert providers when these critical steps are missed, and some systems have the ability to take the provider directly to the required activity.

Although exact EHR capabilities will vary from vendor to vendor, most systems support practice-specific, and even clinician-specific, preference lists. These preference lists are comprised of the most commonly used diagnostic codes and can save the clinician a significant amount of time by eliminating the need to routinely search a lengthy database. Some EHRs will automatically pull diagnoses directly from the problem list or those last entered on that patient. However, a balance between convenience and precision of coding is needed. If clinicians presume that the list presented is complete, they may not search the full database; some clinicians may not even realize that a larger database is available. Diagnoses used in the past may not be carefully assessed for continued appropriateness. Erroneous coding may occur, potentially leading to the wrong diagnosis being quickly propagated through the patient’s medical record.

Even if these preference lists are sufficiently comprehensive, nuances to their design and use still exist. These lists should be built so that they are searchable by all commonly used synonyms of a diagnosis. A sufficient amount of information also needs to be entered by the neurologist so that all potentially correct diagnoses are displayed. The diagnosis of hepatic encephalopathy should be easily found by searching for “encephalopathy” or even the abbreviation “enceph” as well as “hepatic.” The preference list order also matters, as there is a user tendency to choose the codes presented first instead of scrolling down to find what are perhaps more accurate codes. Full descriptions of codes should be available to the provider, who in turn has the responsibility to read them to verify that the correct code is selected. Failure to differentiate between similar-sounding codes may result, for example, in the selection of a female-only diagnosis for a male patient, which, if not caught by the medical coders, may lead to delayed claim submission and billing denials.

Nowhere are the potential advantages and pitfalls of the use of an EHR as it relates to coding more apparent than in electronic clinical documentation. EHRs have a number of features and tools, such as the ability to copy previous notes forward, that are designed to facilitate documentation that allows for precise coding. However, if used inappropriately or carelessly, these tools create documentation so lengthy that crucial information may be obscured and inaccuracies and errors may also be introduced. The ability to copy forward previous notes has also led to “note cloning” in which notes are replicated from provider to provider.5 Poor clinical documentation makes accurate coding impossible and may not support medical necessity of care, leading to claim denials.

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Coding of neurologic complications arising from systemic disease is especially complex because these diagnoses may be classified in a variety of ways. Therefore, it is imperative that the medical record documentation be clear and concise to support accurate diagnosis code assignment.

In many cases, coding for systemic disease processes requires providers to first code the underlying condition, followed by the manifestation code. This need for neurologists to occasionally code for non-neurologic systemic diseases further supports the requirement for an integrated, searchable, comprehensive database of codes. Manifestation codes describe the manifestation of an underlying disease, not the disease itself. Therefore, the manifestation code should not be used as the principal diagnosis.6 For example when coding neuromuscular complications of diabetes mellitus (DM), providers will be required to document the following:

  •  1. The type of DM (1 or 2)
  •  2. If the DM is controlled or uncontrolled
  •  3. The manifestation

A patient with documented uncontrolled type 2 DM with polyneuropathy will be assigned the following ICD-9-CM codes:

  •  1. 250.62 Type II DM, or unspecified type, uncontrolled, with neurological manifestations (the underlying condition)
  •  2. 357.2 Polyneuropathy in diabetes (the manifestation)

Failure to assign both codes listed above may result in a claim denial or lost revenue.

As mentioned above, ICD-9-CM codes frequently require the assignment of two diagnosis codes to identify the patient’s condition. ICD-10-CM may require only one diagnosis code to identify the patient’s condition. Using the same example as above (type 2 DM with the neurologic manifestation of polyneuropathy), the ICD-10-CM code will be:

  •  1. E11.42 Type II DM with diabetic polyneuropathy

Innumerable neurologic complications can arise from systemic illnesses. Because of all the possibilities, the assignment of correct diagnosis codes can be challenging; a “one size fits all” code will not always exist for each patient. Frequently an “unlisted” or “not elsewhere classified” code is the best option. However, if a more specific code is available and the medical record documentation is sufficient to support its use, then the most specific code should always be used. More experienced coders will query physicians for additional information in the documentation when appropriate, but providing clear documentation up front will save both the coder and the physician additional work later.

Polyneuropathy is a potential neurologic manifestation of a variety of systemic diseases. Polyneuropathy that is not clearly associated with an underlying disease process will be coded to a lower level of specificity. For example, in ICD-9-CM the code is 356.9, and in ICD-10-CM, G62.9, for “peripheral neuropathy, unspecified.” A few examples of other codes used for polyneuropathies related to systemic diseases include:



Neurologists are frequently consulted for altered mental status. The term “altered mental status” is nonspecific, and, when appropriate, medical record documentation should clearly indicate a diagnosis of encephalopathy. Accurate medical record documentation of encephalopathy will support some of the following code assignments:



Special attention should be given to the assignment of diagnosis codes for toxic-metabolic encephalopathy. While this broad term is used by neurologists as a catchall to refer to encephalopathy due to either a toxic or metabolic etiology, both ICD-9-CM and ICD-10-CM have distinct codes for metabolic encephalopathy and toxic encephalopathy. If the generic diagnosis of toxic-metabolic encephalopathy is documented and no notation of a specific precipitating disease process is included, it will be reported with the same ICD-9-CM and ICD-10-CM codes as toxic encephalopathy. Also, when coding toxic encephalopathy, an additional code to define the toxic substance is required. For example the coding for the initial encounter by a health care provider of a patient with heroin-induced toxic encephalopathy is as follows:

  • ICD-9-CM
  •  1. 349.82
  •  2. 965.01 (Poisoning by heroin)
  • ICD-10-CM
  •  1. G92
  •  2. T40.1x1A (Poisoning by heroin, accidental, initial encounter)

Seizures are a commonly encountered neurologic complication of systemic disease, yet diagnosis code assignment for them can be quite confusing. Both ICD9-CM and ICD-10-CM do distinguish between a one-time seizure and a definitive diagnosis of epilepsy; however they do not distinguish between seizures due to various systemic illnesses. For example, no specific code exists for seizures in the setting of hepatic encephalopathy or seizures due to hyponatremia. A diagnosis of epilepsy should not be carelessly (ie, inaccurately) assigned to a patient’s record, as this diagnosis may have potential future negative implications for that patient. A patient being seen and treated for a one-time episode of seizure activity will be coded with a single code, ICD-9-CM code 780.39 (seizure not otherwise specified), ICD-10-CM code R56.9 (seizure not otherwise specified).

Diagnostic coding gets even more convoluted for some of the rare neurologic complications of systemic disease. As with the more common manifestations discussed, ultimately the final code selection will be dependent upon the supporting documentation. The diagnosis of acquired hepatocerebral degeneration serves as a prime example of the complexity of coding these diagnoses. While Wilson disease has a defined code, 275.1 in ICD-9-CM and E83.01 in ICD-10-CM, acquired (non-Wilsonian) hepatocerebral degeneration does not. According to the American Hospital Association Coding Clinic, ICD-9-CM code 572.2, hepatic coma, should be assigned for a diagnosis of acquired hepatocerebral degeneration.7 This code also includes hepatic encephalopathy (as noted above), and the patient does not actually have to be in a coma to assign this code.7 Although the American Hospital Association has not yet published guidelines to support ICD-10-CM coding, it is anticipated that the ICD-10-CM code assignment will follow that of ICD-9-CM. Therefore, the ICD-10-CM code assignment for acquired hepatocerebral degeneration would be K72.- (additional fourth and fifth digits will be needed to indicate acute versus subacute hepatic failure and the presence or absence of coma).

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Coding for patients with neurologic complications of systemic disease is quite complex, as by definition this is a broad category of illnesses that have underlying disease processes that must also be acknowledged. The transition to ICD-10-CM will add another layer of complexity. If thoughtfully designed, implemented, and used, EHRs have the capability to guide clinicians in highly accurate coding under both ICD-9-CM and ICD-10-CM, as well as foster the creation of strong supporting documentation.

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1. Craft K, Donofrio P, Shepard KM, et al. Practice and payment trends in neurology in 2012. Neurol Clin Pract 2013; 3 (3): 233–239.
2. Health information technology: Initial set of standards, implementation specifications, and certification criteria for electronic health record technology; final rule.75 Federal Register 144 (28 July 2010), 44590-44654.
3. DeVault K, Barta A. ICD-10-CM coder training manual, 2013. 4-5 edition. Chicago: American Health Information Management Association, 2013.
4. Centers for Medicare & Medicaid Services. Questions to ask your systems vendors about ICD-10. Accessed February 28, 2014.
5. AAMC Compliance Officer’s Forum: Electronic Health Records in Academic Medical Centers Compliance Advisory 2. Appropriate documentation in an EHR: use of information that is not generated during the encounter for which the claim is submitted: copying/importing/scripts/templates. Published July 11, 2011. Accessed February 28, 2014.
7. American Hospital Association (AHA) Coding Clinic for ICD-9-CM. 3rd quarter 1995:14.
© 2014 American Academy of Neurology