Case 1
58 year old man.
•Was admitted for sudden onset of abnormal movement on the right side 7 days before.
•His previous history and general clinical examination were unremarkable,
he had no history of hypertension,
diabetes,
headache,
parkinsonism,
or other neurologic diseases.
He was not on any medication.
•At admission,
his blood glucose level was 212 mg/dl.
Urine analysis was negative for ketones.
Thyroid and liver function tests were normal.
The serum concentrations of heavy metals (copper,
iron) were within the reference ranges.
•On neurologic examination,
the patient had choreic movements involving the left upper limb.
CT at admission
Fig.: Non contrast cranial CT shows hiperdensities afecting left basal ganglia, without edema or mass effect.
Fig.: Follow up CT performed after glycemic normalization one week later: non contrast CT (upper images) and after contrast administration (lower images)show mild improvement of basal ganglia hiperdensities.
MRI at admission
Fig.: Left striatum is hyperintense on coronal T1-weighted images
Fig.: T1wi before (upper images) and after contrast administration (lower images) show left striatum hiperintensities with no significant enhancement.
Fig.: There is no evidence of signal changes on gradient echo sequence.
Follow up CT
Fig.: Two years later it remains only a small area of malacia in the left caudate (arrowhead)
Case 2
38 year old woman.
•Diagnostic of DM (probably MODY: Maturity Onset Diabetes of the Young) one month before admission.
•Heterozygous carrier of the D677 MTHF ( Methylene tetrahydrofolate reductase) mutation.
No personal history of neurological illness or drug abuse.
•Family history of DM II ( mother,
maternal uncle and grandmother).
•She complained of sudden onset,
4 days before,
of involuntary movements in left upper and lower limbs.
•Blood glucose value at admission was 335 mg/dl and Hba1c 13%.
No other abnormalities at laboratory data.
•On neurological exam she presented choreic-ballistic movements involving both his left arm and leg and left orofacial dyskinesias.
Otherwise,
the examination was normal.
CT at admission
Fig.: CT brain scan at admission shows bilateral pronounced hyperdensities of the striatum and caudate.
MRI at admission
Fig.: T1-weighted sagittal images show increased signal intensity affecting right basal ganglia.
Fig.: At admission T2-weighted, and FLAIR images clearly demonstrate a high-signal intensity lesion affecting the right striatum and focal low signal intensity in globus pallidus bilaterally
Fig.: At admission there´s no evidence of signal changes on DWIs.
Follow up CT,
two months later.
Fig.: Control CT two months later shows no significant improvement.
Follow up MRI,
two months later.
Fig.: MRI two months later. There is no difference between images at admission and follow up.
Fig.: At follow up (two months later) hyperintensity affecting right pallidus decreased and a new hyperintense lesion on right putamen can be observed.
Fig.: There is evidence of magnetic susceptibility artifacts on gradient echo images. The DWIs showed bright high signal intensity in the right striatum (the ADC values were decreased).
Imaging Findings
- Two patients with hemichorea-hemiballism associated with hyperglycemia underwent CT and conventional MR imaging,
at admission and two years later in case 1 and at admission and two months later in case 2.
- First imaging studies showed CT hyperdensities and T1WI hyperintensities affecting basal ganglia in both cases,
typical radiologic features in hemichorea-hemiballism associated with hyperglycemia.
- MRI images obtained at admission in case 2 was artifacted because the study was performed in the acute state of the abnormal movements.
- Complete clinical remission was achieved after normalization of glucose levels in patient 1,
and follow up MRI images showed a resolution of the previously documented striatal hyperintensity.
- Patient 2 had a poor glycemic control despite insuline therapy.
She had no clinical improvement, with symptoms persisting during follow-up,
two months later.
Imaging findings shows persisting striatal hyperintensity and a new lesion in the right pallidus.
DISCUSSION
Hemichorea-hemiballism associated with hyperglycemia was first described in 1982.
It isa rare entity but represents about 2-5% of the causes of hemiballism,
affecting almost exclusively elderly women.
This syndrome is considered benign with good prognosis,
however there have been cases with persistence of dyskinesia after several years or even have required surgical treatment.
Although a significant association between hyperglycemia and hyperintensity on T1-weighted MR images has been reported,
the mechanism underlying the imaging findings is still unknown.
However several hypotheses have been proposed to explain the pathophysiology and the variation in MRI findings and clinical symptoms:
- The susceptibility of Asians to this disorder,
suggests a possible genetic predisposition.
- Petechial hemorrhage with blood-brain barrier breakdown in the striatum has been suggested as a plausible mechanism.
- The decreased gamma aminobutyric acid activity due to its metabolism as an alternate energy substrate during hyperglycemic crisis has been proposed.
- It has been postulated that shortening of T1 relaxation time can result from the protein hydration layer inside the cytoplasm of gemistocytes (swollen reactive astrocytes,
containing a rich protein content,
that usually appear during acute injury).
- Myelinolysis and calcifications affecting basal ganglia have been suggested as possible mechanisms.
Most recent studies converge towards a common hypothesis of a metabolic alteration of striatal neurons:
- Hyperglycemia can cause a decrease in regional cerebral blood flow.
Cerebral hypoperfusion may result from an increase in cerebrovascular resistance due to the higher brain water content during hyperglycemia or to a loss of flow regulation caused by impaired metabolism.
Resulting metabolic derangement stimulates the reaction of astrocytes,
which become gemistocytes (causative the shortening of T1 relaxation).
- Petechial hemorrhage occurs in areas that suffer from the more severe ischemic damage.
Although the ischemic or hyperglycemic insult occurs acutely,
the pathologic changes may occur constantly,
as evidenced by the progressive changes seen on MR images and the persistence of chorea seen in some patients.