Non-ketotic hyperglycaemic hemichorea

Non-ketotic hyperglycaemic hemichorea (NHH) is a rare cause of T1 bright basal ganglia and one of the neurological complications of non-ketotic hyperglycaemia, along with non-ketotic hyperosmolar coma and non-ketotic hyperglycaemic seizures

NHH is most frequently reported in elderly patients, typically Asian, who have type 2 diabetes, although it may represent publication bias 2. The majority of cases published involved female patients 4.

Chorea develops rapidly and can be either unilateral or bilateral and is seen during episodes of non-ketotic hyperglycaemia. Symptoms usually resolve upon normalisation of glucose levels. 

The exact underlying pathophysiology of changes seen on imaging of patients with non-ketotic hyperglycaemic hemichorea is not fully understood 1,2

Some hypothesised mechanisms include 5

  • hyperviscosity secondary to hyperglycemia, leading to regional blood-brain barrier disruption and metabolic damage
  • augmented sensitivity of dopaminergic receptors in post-menopausal period (possibly explaining the female predominance in reported case series)
  • decreased gamma-aminobutyric acid (GABA) availability in striatum secondary to non-ketotic state

CT of the brain initially is normal, but later it can demonstrate subtle hyperdensity in the striatal region (caudate nuclei and putamen) 2,7. Findings tend to be contralateral to the body side affected by hemiballistic, hemichoreic movements. 

MRI of the brain is the modality of choice for assessing possible non-ketotic hyperglycaemic hemichorea and typically demonstrates signal changes particularly in the putamen and/or caudate 1-3. If the changes are unilateral, then they are contralateral to the symptomatic side 2

  • T1: hyperintense
  • T2/FLAIR: variable but generally hypointense 
  • DWI: shows restricted diffusion

Overall, the hyperintensity on T1WI sequence is the most consistent finding of the disease. Other associated findings do not present the same frequency and tend to vary 6.

Imaging findings gradually resolve after glycemia correction. However, they tend to return to baseline more slowly than the clinical findings 3.

Symptoms and imaging findings usually resolve upon normalisation of glucose levels 7

The main MRI differential is that of other causes to increased T1 signal in the basal ganglia (including Wilson's disease) and of a striatocapsular infarct 6

Some causes of striatal hyperdensity on CT include 6:

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Article information

rID: 21924
Section: Pathology
Synonyms or Alternate Spellings:
  • Non-ketotic hyperglycaemic hemichorea (NHH)
  • Nonketotic hyperglycaemic hemichorea (NHH)
  • Nonketotic hyperglycaemic hemichorea
  • Non-ketotic hyperglycemic hemichorea (NHH)
  • Non-ketotic hyperglycaemic hemichoreas

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