Major or Mild Neurocognitive Disorder With Lewy Bodies 619
For mild neurocognitive disorder with Lewy bodies, code 331.83 (G31.84). ( Note:  Do not
use the additional code for Lewy body disease. Behavioral disturbance cannot be coded
but should still be indicated in writing.)
Diagnostic Features
Major or mild neurocognitive disorder with Lewy bodies (NCDLB), in the case of major
neurocognitive disorder (NCD), corresponds  to the condition known as dementia with
Lewy bodies (DLB). The disorder includes  not only progressive cognitive impairment
(with early changes in complex attention and ex ecutive function rather than learning and
memory) but also recurrent complex visual hallucinations; and concurrent symptoms of
rapid eye movement (REM) sleep behavior diso rder (which can be a very early manifes-
tation); as well as hallucinations in other sensory modalities, depression, and delusions.
The symptoms fluctuate in a pattern that can resemble a delirium, but no adequate under-
lying cause can be found. The variable pres entation of NCDLB symptoms reduces the like-
lihood of all symptoms being observed in a brief clinic visit and necessitates a thorough
assessment of caregive r observations. The use of assessment scales specifically designed to
assess fluctuation may aid in diagnosis. Anot her core feature is spontaneous parkinson-
ism, which must begin after the onset of cognit ive decline; by convention, major cognitive
deficits are observed at least 1 year befo re the motor symptoms. The parkinsonism must
also be distinguished from neuroleptic-induce d extrapyramidal signs.  Accurate diagnosis
is essential to safe treatment planning, as up  to 50% of individuals with NCDLB have se-