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Neurology India, Vol. 54, No. 4, October-December, 2006, pp. 440-442 Brief Report Diabetic nonketotic hyperosmolar state: Interesting imaging observations in 2 patients with involuntary movements and seizures Shobha N, Sinha S, Taly AB, Pal PK, Chandrasekhar HS Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore Code Number: ni06150 Abstract We report two patients of diabetic nonketotic hyperosmolar state presenting acutely with "self-limiting hemichorea - hemiballismus" and "generalized convulsive status epilepticus". CT scan in both the patienta revealed a hyperdense nonenhancing basal ganglia. Magnetic resonance imaging brain of patient 1 showed it to be hyperintense on T1W image and iso-hyper intense on T2W image, minimally enhancing with contrast injectionKeywords: CT scan, diabetic nonketotic hyperosmolar, hemichorea - hemiballismus, Magnetic resonance imaging, nonketotic hyperosmolar state, seizures. Introduction Diabetic nonketotic hyperosmolar (DNKH) state manifests with diverse neurological manifestations that include clouded sensorium, partial motor seizures, transient hemiplegia, chorea, hemiballismus and hemichorea - hemiballismus.[1],[2]We describe interesting neuroimaging observations (CT/MRI) in two patients of DNKH, one presenting with involuntary movements and the other with status epilepticus. Case Reports Case 1 A 55-year-old lady presented with history of eight days duration of sudden onset involuntary movements of right side, first involving the upper limb and six hours later involving the homolateral lower limb. She was on insulin for diabetes for the past seven years. There was no other significant history. She was conscious, alert with normal higher mental functions and cranial nerve examination. She had continuous, violent, flinging involuntary movements of the right upper and lower extremities that persisted but significantly reduced during sleep. Her random blood sugar was 292 mg% and, serum osmolality was 317 milli-osm/L. Urine analysis did not reveal ketones. Peripheral blood smear for acanthocytes was not performed. A diagnosis of "diabetic nonketotic hyperosmolar state" causing hemichorea and hemiballismus was made. CT brain (plain and contrast) revealed nonenhancing hyperdense caudate and putamen on the left side. On MRI brain, the lesion appeared hyperintense on T1WI and isointense on T2WI, enhancing with contrast injection [Figure - 1]. Her blood sugar was controlled with insulin. She required multiple medications for these involuntary movements like sodium valproate, clonazepam and carbamazepine. These movements decreased after a week and completely subsided within a fortnight. After six months, there was no neurological deficit or involuntary movement. Case 2 She was a 60-year-old lady, a diabetic of two years duration and was on oral hypoglycemic agents. She presented to us with history of recurrent episodes of generalized tonic-clonic seizures and altered sensorium for five hours. There was no other relevant history. At presentation, patient was unconscious (post-ictal state) with Glasgow Coma score of 6. She did not have any focal neurological deficit. Her blood sugar was 543 mg% but urinary ketone bodies were absent. A diagnosis of "diabetic nonketotic hyperosmolar state" manifesting as generalized convulsive status epilepticus was considered. The CT of brain (plain and contrast) showed hyperdense nonenhancing left caudate and putamen [Figure - 2]. MRI could not be performed. She received parenteral sodium valproate and insulin. The seizures stopped immediately and patient recovered completely within three to four days. She was lost to follow-up. Discussion Hemichorea- hemiballismus (HCHB) is a characteristic relatively benign disorder affecting the elderly and may often be the presenting manifestation of hyperglycemia. Hemiballismus often evolves into hemichorea; and therefore the term Hemichorea- hemiballismus syndrome is used.[1],[2] Partial motor seizures, especially "Epilepsia partialis continua" are commonly described in these diabetic patients with nonketotic hyperosmolar coma. But generalized convulsive status epilepticus is rare.-[3] Characteristic imaging features in HCHB are attributed to mild ischemia in the territory of the lateral striate branches of the middle cerebral artery.[4] The lesions are hyperdense on plain CT scan. They are hyperintense on T1WI and remain so in T2WI. SPECT studies might show hypoperfusion of same lesions. Follow-up studies depict resolution of the lesions in the abnormal basal ganglia.[1] The resolution of these lesions indicates that they are not calcification. Another differential diagnosis one might consider is petechial hemorrhage. Positron emission tomography studies show marked reduction in cerebral glucose metabolism in the lesions on T1W MRI providing direct evidence of regional metabolic failure.[5] Gradient echo MR imaging is however normal in HCHB, whereas diffusion weighted imaging and the apparent diffusion co-efficient map show restricted diffusion, which suggests hyperviscosity with cytotoxic edema and not petechial hemorrhage.[6] It is known that lesions in the subthalamus, caudate and putamen (indirect pathway) can result in reduced pallidal activity and thalamic disinhibition, producing ballistic movements. During ischemia, neurons in the indirect pathway become functionally incompetent, whereas neurons in the direct pathway are spared and become burst generating. The over-activity in the direct pathway with the resulting metabolic derangement stimulates the reaction of astrocytes, which transform into gemistocytes and result in the shortening of T1 relaxation time along the tract.[7] Recently, an interesting hypothesis has been put forward by Pisani et al[8] suggesting that, simultaneously with the hyperglycemia, dysmetabolic change occurs in peripheral red blood cells. The formation of acanthocytes might be somehow involved in a cross-reaction with striatal antigens. Histopathologic examination of the biopsied putamen shows gliotic brain tissue with abundant gemistocytes that usually appear during acute injury and shrink gradually.[7] Astrocytes play an important role in maintaining an appropriate ionic composition in the extracellular fluid. When the astrocytes fail, excessive neuronal discharges become inevitable leading to hyperkinesis. Outcome of involuntary movements are usually benign, as they tend to subside with metabolic control.[9] Hyperdense basal ganglia on CT in a diabetic patient with nonketotic hyperosmolar coma can be seen without manifesting as hemichorea-hemiballismus as exemplified by our second patient. She had similar imaging features but presented with status epilepticus and the occurrence of seizures expend the spectrum of the clinical picture, possibly by involving her cortical neurons. However, MRI could not be performed. This raises several questions especially regarding the cause and effect relation of these imaging to involuntary movements and seizures. Whether it means an abnormal underlying dysmetabolic state needs to be considered. Thus, HCHB is not always a self-limiting disorder and is associated with DNKH state and interesting radiological features. The cause and effect of the radiological observations and clinical manifestation are not known conclusively. References
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