4.1 Nervous System Conditions for CDI

4.1 Nervous System Conditions for CDI

Quick Answer: Inpatient CDI does not finish with CVA, AMS, or seizure. Query for stroke type and laterality, the type and cause of encephalopathy, epilepsy versus a provoked seizure versus status epilepticus, clinically significant cerebral edema, and pathologic coma versus sedation. Metabolic encephalopathy can group as an MCC when a provider documents it, indicators support it, and it is not inherent to the principal diagnosis. The 2026 ACDIS/AHIMA query standard requires nonleading, clinically relevant options plus Other, please specify (or similar) and forbids reimbursement or quality-outcome language.

The Association of Clinical Documentation Integrity Specialists (ACDIS) Certified Clinical Documentation Specialist (CCDS) exam puts nervous-system work in Domain II (anatomy, physiology, pathophysiology, pharmacology, and terminology). Items are mostly application and analysis. You are not asked to recite a corticospinal tract. You are asked whether the record supports a reportable diagnosis, whether a query is the right tool, and whether a tempting MCC is clinically inherent to the condition that occasioned the stay.

This independent OpenExamPrep section helps learners study those inpatient skills. It is not an ACDIS product and does not claim partnership, official review, or approval by ACDIS, the American Health Information Management Association (AHIMA), the American Hospital Association (AHA), or the Centers for Medicare & Medicaid Services (CMS).

Acute cerebrovascular accident versus the word stroke

Cerebrovascular accident (CVA) at the bedside is a family of diseases: ischemic cerebral infarction, intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH), and sometimes hemorrhagic conversion of an infarct. Those entities do not group the same way. A problem list that says only CVA is unfinished work.

Clinical indicators that a stroke is acute this admission include sudden focal deficits, an elevated National Institutes of Health Stroke Scale (NIHSS), a last-known-well timestamp, thrombolysis with alteplase or tenecteplase, mechanical thrombectomy, a diffusion-weighted MRI lesion, a large-vessel occlusion on CT angiography, or a hematoma on noncontrast CT. Those indicators do not let the CDI specialist code the CTA. They let you query the provider for a specific diagnostic statement.

Query for ischemic versus hemorrhagic disease (and conversion if neurosurgery describes it); laterality of the infarct and of hemiparesis, hemiplegia, or monoplegia; whether a deficit is a current condition under treatment or only a remote sequela; dominant versus nondominant side when paralysis laterality is known; and acute event versus personal history of CVA with no new deficit and no acute infarct or hematoma.

Original scenario. Ms. R., 71, arrives with dense left face-arm-leg weakness, NIHSS 14. Noncontrast CT shows no blood. CTA shows a right M1 occlusion. She receives tenecteplase and proceeds to thrombectomy with TICI 2b reperfusion. The day-2 progress note says CVA, improving. The discharge summary says history of CVA with residual weakness. Concurrent CDI should not recode the stay as a late-effect stroke and should not invent a middle-cerebral-artery code from the radiology header. A nonleading query asks the attending to specify ischemic infarction versus hemorrhage, laterality, and whether left hemiparesis is a current deficit of this acute event. Cite NIHSS, CTA, thrombolysis, and the exam. Do not mention case mix or SOI.

Transient ischemic attack (TIA) is a transient episode without infarction. If deficits persist and MRI shows restricted diffusion, the clinical diagnosis may have become infarction — only a provider makes that change. Do not upgrade TIA because you prefer the diffusion-weighted image.

Hemiplegia and hemiparesis that are evaluated and treated can meet Uniform Hospital Discharge Data Set (UHDDS) secondary-diagnosis criteria (clinical evaluation, treatment, extra monitoring, or extended length of stay). Weak in a nursing flowsheet is not the same documentation. If dominance is never stated, query rather than assuming that right-handedness equals left-hemisphere dominance without a provider link. ICD-10-CM has default assumptions for unspecified dominance; a query is cleaner than silently accepting the default when occupational therapy already recorded handedness.

Present-on-admission (POA) for a community-onset stroke worked up in the emergency department before the inpatient order is Y. Hemorrhagic conversion that clearly begins after admission is a different POA conversation and must follow the record, not a CDI preference for a CC.

Medications that support acuity without substituting for a diagnosis include tenecteplase or alteplase, aspirin after hemorrhage is excluded, a heparin infusion for selected dissections or stents, and nimodipine when aneurysmal SAH vasospasm prevention is underway.

Encephalopathy: type, cause, and the inherent-condition trap

Altered mental status (AMS), confusion, delirious, and not at baseline are symptoms. Domain II expects you to seek a type (metabolic, toxic, hepatic, hypertensive, anoxic or hypoxic, septic, unspecified) and a cause (hyponatremia, uremia, hypercapnia, drug accumulation, hypotension after return of spontaneous circulation, and so on).

Metabolic encephalopathy as a possible MCC. MS-DRG logic can treat specified encephalopathies as MCCs. You do not memorize an unpublished relative-weight table for the exam. You do memorize the clinical-validation and inherent-condition traps. If the principal diagnosis is already a condition whose definition includes encephalopathy (hepatic encephalopathy as the reason for admission in decompensated cirrhosis), adding a second metabolic encephalopathy MCC because sodium is 128 is a denial magnet. If the principal diagnosis is community cellulitis, the patient is newly oriented only to self, BUN is 64, sodium is 118, and lactulose is not in play, a nonleading query for type and cause is the CCDS skill.

Never put please document metabolic encephalopathy so this case has an MCC in a query. The August 2026 ACDIS/AHIMA Guidelines for Achieving a Compliant Query Practice bar reimbursement and quality-outcome language. Cite the indicators (GCS 13, sodium 118, BUN 64, CAM-ICU positive) and leave independent judgment with the provider.

Original scenario. Mr. K. is admitted for lower-extremity cellulitis. At 02:00 he is GCS 13, CAM-ICU positive, sodium 119 mEq/L, and glucose 41 mg/dL after insulin. The hospitalist writes AMS, likely Na. CDI sends a multiple-choice query with clinically relevant choices: metabolic encephalopathy related to hyponatremia; metabolic encephalopathy related to hypoglycemia; toxic encephalopathy; AMS explained by fever and pain without a separate encephalopathy diagnosis; other, please specify; unable to determine. That is type and cause. It is not a yes/no that introduces a new diagnosis. Under the 2026 guidance, yes/no queries may not introduce a new diagnosis.

Do not invent a CMS-mandated sodium cutoff. Ammonia, the basic metabolic panel, the arterial blood gas, TSH, B12, EEG, and the medication list are indicators. Delirium and encephalopathy are not interchangeable chase words; if the record uses both loosely, query rather than swapping them to pursue an MCC. Hypertensive encephalopathy is a hypertensive emergency with acute brain dysfunction, not chronic hypertension plus mild forgetfulness. Anoxic encephalopathy after cardiac arrest needs a provider diagnosis; a CT that does not show herniation yet neither codes it nor rules it out.

Seizures, epilepsy, and status epilepticus

A provoked seizure (alcohol withdrawal, tramadol, hypoglycemia, acute ICH) is not automatically epilepsy. Epilepsy is a chronic predisposition to unprovoked seizures. Status epilepticus — ongoing seizure activity or incomplete recovery between seizures, often treated with benzodiazepines, a loading antiseizure medication, continuous EEG, and sometimes intubation — is a different, higher-acuity diagnosis than had a seizure in the field.

Do not code epilepsy from a single withdrawal seizure. Do not code status from an EEG technician's preliminary comment. Do not relabel a post-ictal state as metabolic encephalopathy unless the provider documents a separate encephalopathic process. Treatments that function as indicators include lorazepam, a midazolam infusion, levetiracetam or fosphenytoin loads, propofol or pentobarbital for refractory status, and a continuous EEG order.

Original scenario. A 44-year-old with alcohol-use disorder seizes once in the ED, receives 2 mg lorazepam, returns to baseline in 25 minutes, and has a normal EEG the next morning. The ED note copies epilepsy from an old problem list. Neurology writes provoked withdrawal seizure, not epilepsy. CDI should query or clarify the outdated problem list rather than report chronic epilepsy. The 25-minute post-ictal period does not, by itself, establish metabolic encephalopathy.

Cerebral edema and coma

Radiology language of loss of sulci, blurring of gray-white differentiation, or edema is query bait, not a code. Many large infarcts have expected swelling. Clinically significant cerebral edema is suggested when the team uses hypertonic saline, mannitol, controlled hyperventilation, an external ventricular drain, or hemicraniectomy, or when neurosurgery documents herniation risk. Then ask the treating provider to diagnose or exclude clinically significant cerebral edema. Because a yes/no query cannot introduce a new diagnosis, first-time capture is usually multiple-choice, including other/please specify and an option that the imaging change is expected infarct swelling without a separate edema diagnosis.

Coma is not propofol for ventilator synchrony, is not groggy, and is not a GCS 3T that is entirely iatrogenic. Pathologic coma (structural, anoxic, metabolic) needs a provider statement. Induced coma is a treatment. If the record mixes them, query. A GCS of 8 or less often accompanies an intubation decision; it remains an indicator, not a coma code.

Putting the AMS query together

Source every indicator (ED history and physical, basic metabolic panel, arterial blood gas, CT, GCS, CAM-ICU, drug list). Offer only clinically relevant options — do not offer hypertensive encephalopathy for a blood pressure of 138/84, and do not offer hypernatremia for sodium 122. Include Other, please specify. Keep reimbursement words out. If you are validating a diagnosis already written that looks unsupported, multiple-choice with confirmed with support, ruled out, no longer valid, and an alternative diagnosis is the 2026-preferred clinical-validation pattern. Verbal queries still need date, time, people, indicators with source, a nonleading statement, options if any, and a response that reaches the permanent health record before coding.