Sydenham Chorea

Sydenham Chorea, a manifestation of rheumatic fever, is believed to be an autoimmune disorder, induced by group A streptococcus. ^[1] Pathologic examination of the brain during acute illness has shown nonspecific neuronal swelling and degeneration, arteritis, and petechial hemorrhages that have been widespread but have usually included the caudate and putamen. ^[2] Magnetic resonance imaging (MRI) has revealed lesions in the caudate and putamen in some but not all patients during the acute stage of Sydenham Chorea, supporting the belief that striatal dysfunction is the cause of the chorea. ^[3-7] However, none of these reports documented permanent lesions in the striatum on MRI. Long-term follow-up studies of patients with Sydenham Chorea reported neurologic and psychiatric sequelae and central dopaminergic hypersensitivity. ^[2] Because of the retrospective nature of the studies and different methods of evaluation, the frequency and character of the residua have been uncertain. This case is the first report of MRI confirming permanent injury in the caudate after Sydenham Chorea.

Case report.

A 3-year-old boy had the sudden onset of involuntary movements of the left arm and leg 2 days before admission to the hospital. There was no history of preceding or associated trauma and illness. The movements disappeared during sleep. A CT of the head at an outside hospital showed hypodensity of the right caudate. There was a strong paternal family history of vascular disease.

On admission he was an alert, irritable, afebrile child with normal vital signs, growth, and development. There was no rash or arthritis. The cardiac examination was normal. The left arm and leg had choreic movements and reduced deep tendon reflexes. Plantar reflexes were flexor. He was able to walk.

Throat culture grew beta hemolytic group A streptococcus. Antistreptolysin-O titer was 200 Todd units (normal, less than 200). CBC, ESR, ANA, thyroid function tests, plasma lactic acid and pyruvic acid, serum ceruloplasmin, plasma amino acids, serum lipids, ECG, and cardiac ultrasound were normal. An MRI of the brain revealed abnormal signal and enlargement of the right caudate and putamen (Figure 1). At a later date, protein C, protein S levels, and activated partial thromboplastin time were normal.

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Figure 1. MRI of patient at presentation. (A) Axial T₁-weighted image at the level of the basal ganglia shows swelling of the right caudate nucleus and putaman (arrows). (B) Axial proton density image, at same level as A, displays diffuse increased signal involving the same structures (arrows).

He was treated with penicillin and was subsequently placed on prophylactic penicillin. The cardiac examination remained normal during the subsequent 3 years. The chorea improved after 6 days and completely resolved after 2 weeks, at which time the neurologic examination was entirely normal. MRI (Figure 2) 3 months after the illness showed resolution of the swelling, but abnormal signal persisted in the right caudate and putamen. MRIs at 22 months and 40 months (Figure 3) after the chorea were similar and disclosed a cystic appearance of the right caudate and putamen. At age 6 years (40 months after the illness), the parents reported once a month seeing very brief twitching movements of the fingers of the left hand. On neurologic examination, he had minimal choreic movements of the left hand, slight hyperreflexia, and pronation of the outstretched left arm.

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Figure 2. Axial T₁-weighted image 3 months later shows resolution of mass effect within the right basal ganglia. Cyst-like changes are present.

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Figure 3. Axial T₁-weighted image 40 months after initial illness reveals stable cystic changes within the right caudate nucleus and putamen.

Discussion.

In the absence of cardiac disease or other signs of rheumatic fever, the diagnosis of Sydenham Chorea can be difficult. This child had a compatible clinical course with evidence of streptococcal infection; other causes of chorea were excluded. Although not unequivocally certain, the diagnosis of Sydenham Chorea is very probable.

CT of the brain during Sydenham Chorea is frequently normal. ^[8] How often MRI of the brain is abnormal is uncertain. Most previous reports were published because of an abnormality in the MRI, but there is one definite case of a patient with Sydenham Chorea with carditis and other signs of rheumatic fever who had a normal MRI 34 days after the onset of the chorea when still symptomatic. ^[7] In a quantitative MRI study only 2 of 24 children with Sydenham Chorea had signal abnormalities, one in the caudate and the other in the parietal lobe. ^[9] The study did demonstrate that mean values for the size of the caudate, putamen, and globus pallidus in the children with chorea were larger than normal control subjects, but the size of the basal ganglia in the two groups overlapped extensively. Entrance into the study ranged from 1 to 12 months (mean, 4.4 months) from onset of the chorea; the signal abnormalities, present early in the course, could have resolved by the time of the imaging. ^[10] In summary, current information suggests that few individuals with Sydenham Chorea have abnormalities on MRI, but further observations are necessary.

The usual course of MRI abnormalities is also uncertain. Three of the previously reported five cases with MRI abnormalities had complete or almost complete resolution within 6 to 14 months. ^[4-6] Two cases did not have long-term follow-up, so that the outcome was unknown. ^[3] Our patient is the first to demonstrate unequivocal permanent changes.

Based on our case and previous observations, the MRI findings in Sydenham Chorea are extremely varied. MRI cannot confirm the diagnosis but can exclude other causes of the chorea. This case provides evidence that Sydenham Chorea can cause permanent neurologic injury.