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 this 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 hyperglycaemia, leading to regional blood-brain barrier disruption and metabolic damage
- the augmented sensitivity of dopaminergic receptors in a postmenopausal period (possibly explaining the female predominance in reported case series)
- decreased gamma-aminobutyric acid (GABA) availability in the striatum secondary to the 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 hyperglycaemia correction. However, they tend to return to baseline more slowly than the clinical findings 3.
Treatment and prognosis
Symptoms and imaging findings usually resolve upon normalisation of glucose levels 7.
Some causes of striatal hyperdensity on CT include 6:
- 1. Zhou Y. World Journal of Neuroscience. 2012;02 (02): . doi:10.4236/wjns.2012.22020
- 2. Wintermark M, Fischbein NJ, Mukherjee P et-al. Unilateral putaminal CT, MR, and diffusion abnormalities secondary to nonketotic hyperglycemia in the setting of acute neurologic symptoms mimicking stroke. AJNR Am J Neuroradiol. 2004;25 (6): 975-6. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 3. Lai PH, Tien RD, Chang MH et-al. Chorea-ballismus with nonketotic hyperglycemia in primary diabetes mellitus. AJNR Am J Neuroradiol. 1996;17 (6): 1057-64. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 4. Postuma RB, Lang AE. Hemiballism: revisiting a classic disorder. Lancet Neurol. 2003;2 (11): 661-8. Pubmed citation
- 5. Narayanan S. Hyperglycemia-induced hemiballismus hemichorea: a case report and brief review of the literature. J Emerg Med. 2012;43 (3): 442-4. doi:10.1016/j.jemermed.2010.05.003 - Pubmed citation
- 6. Wilson TJ, Than KD, Stetler WR et-al. Non-ketotic hyperglycemic chorea-hemiballismus mimicking basal ganglia hemorrhage. J Clin Neurosci. 2011;18 (11): 1560-1. doi:10.1016/j.jocn.2011.03.010 - Pubmed citation
- 7. Hegde AN, Mohan S, Lath N et-al. Differential diagnosis for bilateral abnormalities of the basal ganglia and thalamus. Radiographics. 31 (1): 5-30. doi:10.1148/rg.311105041 - Pubmed citation