Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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November 4, 2021
Nonketotic Hyperglycemic Hemichorea (NHH)
- Background:
- The exact pathophysiology is not fully understood, but some hypotheses include hyperviscosity secondary to hyperglycemia leading to blood-brain barrier disruption and metabolic damage; other hypotheses include decreased gamma-aminobutyric acid (GABA) availability in the striatum secondary to a state of ketosis in noncontrolled diabetes.
- Clinical Presentation:
- NHH is most frequently reported in older patients. Most published cases involved female patients.
- Repetitive, brief, irregular, somewhat rapid involuntary movements (chorea) that start in one part of the body and ballismus, which is a type of chorea that presents with broader and more intense movements than chorea, develop pretty quickly, both unilaterally and bilaterally, during the nonketotic hyperglycemia episodes.
- A history of inadequate metabolic control is present in most cases.
- Key Diagnostic Features:
- CT of the brain might be normal; later subtle hyperdensity in the striatal region (caudate and putamen) can be demonstrated.
- MRI shows signal changes significantly in the putamen and/or caudate nuclei, more frequently unilateral, and a T1-hyperintense, T2/FLAIR-variable but generally hypointense, DWI high-diffusion signal. T1 hyperintensity is the most consistent finding.
- Differential Diagnoses:
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Other causes of MRI T1 increased signal in the striatal region include Wilson disease (that has T2 hyperintensity in contrast to NHH), hepatic failure, and toxins like carbon monoxide or methanol, all of them usually appearing as bilateral lesions.
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Other, less frequent pathologies like Japanese encephalitis show restricted diffusion on DWI and a hamartoma in type 1 neurofibromatosis, which is unilateral and has a T2 iso- or hyperintense to gray matter signal.
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CT causes of striatal hyperdensity include basal ganglia calcification and tuberous sclerosis, both usually unilateral, and finally Tay-Sachs disease that generally presents with multiple lesions.
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Treatment:
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Both symptoms and imaging findings resolve when normal glucose levels are corrected; in 20% of cases, symptoms persist and treatment with antipsychotic drugs such as fluphenazine, haloperidol, or risperidone is needed.
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Other drugs, such as reserpine, deutetrabenazine, and tetrabenazine, may also help. However, improvement may be limited.
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