Wilson's disease: MRI features.

A 15-year-old boy presented with coarse tremors of right hand and dysarthric speech. Neurologic examination demonstrated Kayser-Fleischer rings and dystonic tremor of the right hand. Serum ceruloplasmin and urine copper studies established the diagnosis of Wilson's disease. Brain MRI showed bilateral T2 hyperintensity involving putamen, thalami, and brainstem. Involvement of brainstem revealed the characteristic "double panda sign."

A 15-year-old boy presented with history of coarse tremors of right hand and dysarthric speech since 1 year. Neurologic examination revealed Kayser–Fleischer rings in both the eyes and dystonic tremor of the right hand. Serum ceruloplasmin and urine copper studies established the diagnosis of Wilson's disease. No evidence of jaundice or cirrhosis was seen to imply hepatic involvement. Liver function tests were within normal limits.

Magnetic resonance (MR) imaging showed T2 and FLAIR hyperintense lesions involving bilateral thalami, midbrain, and pons. The lesions were hypointense on T1-weighted sequence and showed no evidence of restricted diffusion. Only subtle hyperintense signal on T2/FLAIR images was seen in the lentiform nuclei [Figure 1]. Caudate nuclei, cerebellar white matter, centrum semiovale and subcortical white matter were not involved. Involvement of the midbrain demonstrated that the characteristic magnetic resonance imaging (MRI) appearance of the “face of the giant panda” and dorsal pontine signal abnormalities resembled the face of a cub [Figures 2 and 3]. Face of the giant panda and her cub constitute the “double panda sign”[1] which is characteristic for this disease and has been described only in few reports.

Figure 1

T2-weighted axial MRI demonstrates hyperintense signal in the bilateral thalami and putamen

Figure 2

T2-weighted axial MRI demonstrates the “face of the giant panda” in the midbrain with high signal in tegmentum and normal red nuclei (arrow)

Figure 3

T2-weighted axial MRI reveals the “face of the miniature panda” in pons with hypointensity of central tegmental tracts (arrow) with hyperintensity of aqueductal opening to fourth ventricle

Wilson's disease is an inborn error of copper metabolism that is characterized by deficiency of ceruloplasmin, the serum transport protein for copper. Copper is collected in the liver, and after hepatic binding sites are saturated, it is released. Systemic disease then develops and there is abnormal accumulation of copper in the brain, particularly in the putamen and globus pallidus.[2] The neurologic manifestations associated with Wilson's disease are understood to be secondary to buildup of cerebral copper at levels adequate to destroy nerve cells. Edema, necrosis, and spongiform degeneration are the histopathological changes that are observed in Wilson's disease involving the brain.[3] MRI not only provides biochemical information on heavy metal distribution in brain tissue but also gives an insight into the pathologic and anatomic correlates of clinical signs and symptoms in Wilson's disease. Interval changes seen on follow-up MR imaging have good correlation with clinical symptoms and can be useful in evaluating the clinical response to treatment of children with Wilson's disease.[4]

The midbrain “face of the giant panda” sign[5] consists of high signal intensity in the tegmentum, preservation of signal intensity of the lateral portion of the pars reticulata of the substantia nigra and red nucleus (arrowhead), and hypointensity of the superior colliculus. In addition, a “face of panda cub” is seen within the dorsal part of pons. “Eyes of the panda” are formed from the relative hypointensity of the central tegmental tracts (CTT) (arrowhead) in contrast with the hyperintensity of the aqueduct opening into the fourth ventricle (“nose and mouth of the panda”) bounded inferiorly by the superior medullary velum. The panda's “cheeks” are formed from the superior cerebellar peduncles.[1]