Other neurocognitive disorders. The early symptoms of Huntington’s disease, particu- larly symptoms of executive dysfunction and impaired psychomotor speed, may resemble other neurocognitive disorders (NCDs), such as major or mild vascular NCD.
Major or Mild Neurocognitive Disorder Due to Another Medical Condition 641
Other movement disorders. Huntington’s disease must also be differentiated from other disorders or conditions associated with chorea, such as Wilson’s disease, drug-induced tardive dyskinesia, Sydenham’s chorea, systemic lupus erythematosus, or senile chorea.
Rarely, individuals may present with a course similar to that of Huntington’s disease but without positive genetic testing; this is considered to be a Huntington’s disease pheno- copy that results from a variety of potential genetic factors.
Due to Another Medical Condition
A. The criteria are met for major or mild neurocognitive disorder.
B. There is evidence from the history, physical examination. or laboratory findings that the neurocognitive disorder is the pathophysiological consequence of another medical condition.
C. The cognitive deficits are not better explained by another mental disorder or another specific neurocognitive disorder (e.g., Alzheimer’s disease, HIV infection).
Coding note: For major neurocognitive disorder due to another medical condition, with behavioral disturbance, code first the other medical condition, followed by the major neu- rocognitive disorder due to another medical condition, with behavioral disturbance (e.g., 340 [635] multiple sclerosis, 294.11 [F02.81] major neurocognitive disorder due to multi- ple sclerosis, with behavioral disturbance). For major neurocognitive disorder due to an- other medical condition, without behavioral disturbance, code first the other medical condition, followed by the major neurocognitive disorder due to another medical condition, without behavioral disturbance (e.g., 340 [635] multiple sclerosis, 294.10 [F02.80] major neurocognitive disorder due to multiple sclerosis, without behavioral disturbance).
For mild neUrocognitive disorder due to another medical condition, code 331.83 (631.84).
(Note: Do not use the additional code for the other medical condition. Behavioral distur- bance cannot be coded but should still be indicated in writing.)
A number of other medical conditions can cause neurocognitive disorders (NCDs). These conditions include structural lesions (e.g., primary or secondary brain tumors, subdural hematoma, slowly progressive or normal-pressure hydrocephalus), hypoxia related to hy- poperfusion from heart failure, endocrine conditions (e.g., hypothyroidism, hypercalce- mia, hypoglycemia), nutritional conditions (e.g., deficiencies of thiamine or niacin), other infectious conditions (e.g., neurosyphilis, cryptococcosis), immune disorders (e.g., tempo- ral arteritis, systemic lupus erythematosus), hepatic or renal failure, metabolic conditions (e.g., Kufs’ disease, adrenoleukodystrophy, metachromatic leukodystrophy, other storage diseases of adulthood and childhood), and other neurological conditions (e.g., epilepsy, multiple sclerosis). Unusual causes of central nervous system injury, such as electrical shock or intracranial radiation, are generally evident from the history. The temporal asso- ciation between the onset or exacerbation of the medical condition and the development of the cognitive deficit offers the greatest support that the NCD is induced by the medical condition. Diagnostic certainty regarding this relationship may be increased if the neuro- cognitive deficits ameliorate partially or stabilize in the context of treatment of the medical condition.