G31.83

Dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is a progressive neurodegenerative disease characterized by the abnormal accumulation of alpha-synuclein protein aggregates, known as Lewy bodies, within the neurons of the brain. It is the second most common cause of degenerative dementia in older adults. Pathologically, it is distinct from but shares features with both Alzheimer's disease and Parkinson's disease. DLB is clinically defined by a 'central' feature of progressive cognitive decline and at least two 'core' features: fluctuating levels of alertness and attention, recurrent and detailed visual hallucinations, REM sleep behavior disorder (RBD), and spontaneous parkinsonian motor features. Patients often demonstrate severe sensitivity to neuroleptic (antipsychotic) medications. Management is primarily symptomatic, and an additional code from subcategory F02.8- is required to specify the dementia's severity and the presence or absence of behavioral disturbances.

Clinical Symptoms

  • Fluctuating cognition and alertness
  • Recurrent, well-formed visual hallucinations
  • REM sleep behavior disorder (RBD)
  • Spontaneous parkinsonism (bradykinesia, resting tremor, or rigidity)
  • Orthostatic hypotension
  • Syncope or transient loss of consciousness
  • Urinary incontinence
  • Constipation
  • Frequent falls and postural instability
  • Visuospatial dysfunction
  • Executive dysfunction
  • Excessive daytime sleepiness
  • Severe neuroleptic sensitivity
  • Anxiety and depression
  • Apathy

Common Causes

  • Abnormal accumulation of alpha-synuclein protein (Lewy bodies) in the cerebral cortex and brainstem
  • Synaptic dysfunction and neuronal loss in cholinergic and dopaminergic systems
  • Advanced age (typically 50 years or older)
  • Genetic mutations in the GBA (glucocerebrosidase) gene
  • Presence of the APOE ε4 allele
  • Mutations or polymorphisms in the SNCA (alpha-synuclein) gene
  • Male sex (demonstrated higher prevalence than females)
  • Family history of Dementia with Lewy bodies or Parkinson's disease

Documentation & Coding Tips

Mandatory Dual Coding Requirement

Example: Patient diagnosed with Dementia with Lewy bodies (G31.83). Note also specifies associated Dementia in other diseases classified elsewhere, with behavioral disturbance (F02.811) due to increasing physical aggression and nocturnal wandering. Risk Adjustment: Maps to HCC 51 (Dementia) and supports high-severity chronic condition status.

Billing Focus: Ensure both the etiology code G31.83 and the manifestation code from category F02 are sequenced together.

Distinguish from Parkinson Disease Dementia

Example: Clinical onset of cognitive decline preceded motor symptoms by 6 months, confirming Dementia with Lewy bodies (G31.83) rather than Parkinson disease dementia. Patient exhibits significant fluctuating cognition and well-formed visual hallucinations. Billing: G31.83 is used for the 1-year rule where dementia occurs before or within 1 year of Parkinsonism.

Billing Focus: Documentation must specify the temporal relationship between motor and cognitive symptoms to justify G31.83 over G20 and F02 codes.

Document Specific Behavioral Manifestations

Example: Patient with known G31.83 now exhibiting F02.818 (Dementia in other diseases classified elsewhere with other behavioral disturbance), specifically combative behavior during ADLs and persistent delusional jealousy. Comorbidities: Chronic orthostatic hypotension managed with midodrine. Severity: Severe cognitive impairment with significant safety risk.

Billing Focus: Specify the exact nature of behavioral disturbances (agitation, aggression, wandering) to support F02.81- series codes.

Incorporate REM Sleep Behavior Disorder and Autonomic Symptoms

Example: Patient presents with G31.83 and concurrent G47.52 (REM sleep behavior disorder). Documented history of acting out dreams and frequent falls secondary to autonomic instability (I95.1). Documentation supports the clinical triad of DLB. Care involves high-level complexity for multi-system neurodegeneration.

Billing Focus: Linking associated conditions like RBD or orthostatic hypotension provides a comprehensive clinical picture for high-level E/M coding.

Identify Fluctuating Cognition and Hallucinations

Example: Documentation records marked variations in alertness and attention (fluctuating cognition) and recurrent visual hallucinations of small animals. Diagnosis: Dementia with Lewy bodies (G31.83) with dementia without behavioral disturbance (F02.80). Patient is currently stable on cholinesterase inhibitors.

Billing Focus: Clear documentation of core diagnostic features (hallucinations, fluctuations) validates the choice of G31.83 over G30.9 (Alzheimer's).

Relevant CPT Codes

Related Diagnoses

Hierarchy