Poststreptococcal Dystonia with Bilateral Striatal Enlargement: MR Imaging and Spectroscopic Findings

Abstract

SUMMARY: Isolated bilateral striatal necrosis is an abnormality of the basal ganglia associated with acute dystonia in children. This report describes the development of dystonic movements in a 7-year-old male patient 2 weeks after streptococcal pharyngitis. Dystonia with basal ganglial imaging abnormalities is usually related to structural, metabolic, toxic, traumatic, or vascular disorders.1,2 Swedo et al 3 coined the term "pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection" (PANDAS) to describe them. MR imaging in patients with suspected PANDAS has demonstrated a lack of structural abnormality, though volumetric evaluations revealed enlargement of the basal ganglia. 4This report describes a patient presenting with dystonia and basal ganglial imaging abnormalities following streptococcal infection. Because there is no specific test to confirm this diagnosis, poststreptococcal dystonia was presumptive. To our knowledge, this is the first case report addressing the findings on diffusion-weighted MR imaging and on MR spectroscopy in a patient with poststreptococcal dystonia and striatal enlargement. Case ReportA 7-year-old boy presented with rigidity and difficulty breathing. Diagnosis of streptococcal pharyngitis was made, and he was treated with an aminopenicillin. Two days later, he was unable to get out of bed, and persistent drooling was noted. Dexamethasone was begun, but his condition deteriorated with increasing rigidity, dystonia, drooling, and tremor of the hands. Rigidity and dystonia rapidly progressed, and he developed mutism, dysphagia, and incontinence. Laboratory testing demonstrated borderline high antistreptolysin O titer and a high level of antideoxyribonuclease antibody.Cranial MR imaging demonstrated bilateral T2 hyperintensity in the heads of the caudate nuclei, the putamina, and the external/ extreme capsules. The heads of the caudate nuclei and the putamina were enlarged (Fig 1) and demonstrated minimal restricted diffusion on diffusion-weighted images (Fig 2). Single-voxel MR spectroscopy of the left lentiform nucleus demonstrated elevation of the lipid/lactate peak and a decreased N-acetylaspartate (NAA) peak (Fig 3A).Follow-up MR imaging 1 month later showed no significant change. MR spectroscopy demonstrated continued depression of the NAA peak with interval increase in the choline/creatine ratio compared with the initial MR spectroscopy (Fig 3B).

Striatal structure and function in mood disorders: a comprehensive review

“…As discussed above, hypertrophy seems most likely to be a result of antipsychotic treatment. However, striatal enlargement has been reported with poststreptococcal dystonia (162), suggesting at least the possibility that hypertrophy could occur as a primary process rather than secondary to medication. Another issue is whether anatomical findings might represent primary pathology or occur as a result of anomalous input from other regions.…”

Neuropsychiatric disorder with basal ganglia lesions

“…Neuroimaging is usually normal in PANDAS. However, basal ganglia enlargement and hyperintensities can be seen in some cases 3–5. The MRI brain showed bilateral striatal necrosis in this patient (figure 1).…”

Acute Movement Disorders in Childhood

“…Neurological symptoms usually include dystonia and/or parkinsonism, variably associated with encephalopathy, seizures, ataxia or pyramidal signs [ 120 ]. The most commonly associated infectious agent is Mycoplasma pneumonia [ 122 , 123 , 126 ], but several other possible causes have been reported—such as GABHS, HHV-6 or measles [ 124 , 125 , 127 , 128 , 129 ]. Laboratory investigations do not always clarify if pathogenesis is supported by the infection or immune-mediated mechanisms [ 120 ].…”