Rapidly progressing dementia

Background

• Subacute and accelerated decline, developing over 2 years
• Must rule out Creutzfeldt-Jakob disease (CJD)

Differential Diagnosis

• Creutzfeldt-Jakob disease (CJD), especially when myoclonus is present
• Atypical course of a more common form of dementia
  • Frontotemporal dementia, progressive supranuclear palsy, Lewy body dementia, and Alzheimer dementia
• Limbic encephalitis: short-term memory loss, executive dysfuntion, personality changes, panic attacks, and delusions and hallucinations, as well as seizures
  • Paraneoplastic syndromes
    • Anti-Hu: often found in small cell lung cancer
    • CV2: only found in small cell lung cancer or thymoma
    • Ma2: testicular germ-cell tumours, breast cancer, and NSCLC
    • VGKC
  • Anti-voltage-gated potassium channel encephalopathy (VGKC-E): often has hyponatremia
  • HSV encephalitis
• Hashimoto encephalitis (steroid-responsive encephalopathy): often in patients with other autoimmune disorders, diagnosed with anti-TPO and anti-TG antibodies

Extended Differential Diagnosis

• Vascular
  • Stroke, vascular dementia
  • CADASIL
  • Thrombotic thrombocytopenic purpura (TTP)
  • Hyperviscosity
  • Syndromes/paraproteinemias (polycythemia, monocloncal gammopathies)
  • Hypoxic-ischemic encephalopathy
• Infectious
  • Whipple disease
  • Syphilis
  • Lyme disease
  • Subacute sclerosing panencephalitis (SSPE) (measles)
  • HIV-associated dementia
  • Progressive multifocal leukoencephalopathy (JC virus)
• Toxic/metabolic
  • Vitamin B12 deficiency
  • Thiamine deficiency
  • Niacin deficiency
  • Folate deficiency
  • Uremic encephalopathy
  • Wilson disease
  • Hepatic encephalopathy
  • Porphyria
• Heavy metal toxicity
  • Bismuth toxicity
  • Alcohol toxicity
  • Lithium toxicity
  • Mercury toxicity
  • Arsenic toxicity
  • Lead toxicity
• Electrolyte abnormalities
  • Kuf disease
  • Methylmalonic acidemia
  • Mitochondrial encephalopathies
• Autoimmune
  • Paraneoplastic limbic encephalitis
  • Anti-VGKC-E
  • Hashimoto encephalopathy
  • Lupus cerebritis
  • Neurosarcoidosis
  • CNS vasculitis
  • Celiac disease
• Metastases/neoplastic
  • CNS metastases
  • Primary CNS lymphoma
  • Intravascular lymphoma
  • Lymphomatoid granulomatosis
  • Gliomatosis cerebri
• Iatrogenic/idiopathic
  • Central pontine myelinolysis
  • Insulin-induced hypoglycemia
  • Normal pressure hydrocephalus (NPH)
• Neurodegenerative
  • Alzheimer dementia
  • Creutzfeldt-Jakob disease
• Frontotemporal syndrome
  • Behavioural variant frontotemporal dementia
  • Semantic dementia
  • Progressive non-fluent aphasia
  • Frontotemporal dementia-motor neuron disease
• Parkinson syndrome
  • Dementia with Lewy bodies
  • Corticobasal degeneration
  • Progressive supranuclear palsy
  • Parkinson disease dementia
  • High definition
• Systemic
  • Vasculitis (giant cell arteritis)
  • Sleep apnea

Investigations

• MRI: CJD is the only degenerative condition that causes hyperintensities in DWI and FLAIR