|IMAGES IN PSYCHIATRY
|Year : 2019 | Volume
| Issue : 1 | Page : 77-78
The face of the giant panda: Demystified
Soniya Patankar, Shilpa Sankhe, Abhishek Bairy
Department of Radiodiagnosis, Seth GSMC and KEM Hospital, Mumbai, Maharashtra, India
|Date of Web Publication||24-May-2019|
Dr. Soniya Patankar
C-7, Green Acres Bungalows, Din Quarry Road, Deonar, Mumbai - 400 088, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Patankar S, Sankhe S, Bairy A. The face of the giant panda: Demystified. Ann Indian Psychiatry 2019;3:77-8
Wilson's disease is an inborn error of metabolism having an autosomal recessive pattern of inheritance. It occurs due to the deficiency of ceruloplasmin, the enzyme responsible for copper metabolism leading to abnormal intracellular accumulation of copper. In most of these patients, the excess copper is deposited in the hepatocytes. Once the storage capacity of the liver is exceeded, there is systemic deposition of copper with brain being the most common extrahepatic site. Other sites such as the skeletal system, kidneys, and eyes can also be affected.
Wilson's disease has a prevalence of 1 in 10,000 to 1 in 30000., The key clinical manifestations of the disease are hepatic dysfunction, neurological symptoms, and Kayser–Fleischer rings. Early-onset Wilson's disease usually presents in the second decade of life with hepatic dysfunction, whereas neurological symptoms manifest in the third decade of life. Neurological manifestations can either have tremors or rigidity as the predominant presenting symptom along with dysarthria, athetosis, ataxia, and neuropsychiatric symptoms. These symptoms are believed to occur due to heavy metal deposition in the extrapyramidal system involving the basal ganglia and brainstem.
Although the diagnosis of Wilson's disease is made by raised serum and urinary copper and ceruloplasmin levels, coupled with the presence of Kayser–Fleischer ring due to copper deposition in the cornea on slit-lamp examination, imaging of the brain with the advent of magnetic resonance imaging (MRI) has proved to be a useful adjunct. Genetic analysis of ATP7B gene mutation is highly sensitive for the diagnosis of Wilson's disease as the mutation of this gene responsible for copper transport in hepatocytes is implicated in causing Wilsons disease. The abnormal signal intensity seen due to heavy metal deposition not only supports the diagnosis but also helps the clinician in correlating the neuropsychiatric symptoms of these patients. It also rules out other organic causes which could be responsible for the clinical symptoms.
Wilson's disease has a predilection for affecting the dentatorubrothalamic tract, the pontocerebellar tract, and the corticospinal tract, thereby involving the putamen, globus pallidus, thalami, tegmentum, and tectum of the midbrain and pons. It relatively spares the superior colliculus and red nucleus. In later stages of the disease, secondary changes such as atrophy of the brain parenchyma can be seen.
The paramagnetic effects of heavy metal deposition lead to a decrease in T2 and T1 signal intensity, while the areas of high T2 signal intensity are due to edema, gliosis, areas of necrosis, and cystic degeneration. These alterations in the midbrain give an appearance resembling the “face of the giant panda.”
On T2-weighted MRI, there is hyperintensity in the tegmentum of the midbrain. The red nuclei are spared and remain hypointense forming the eyes of the giant panda.
The preservation of the normal T2 low-signal intensity of the pars reticulate of the substantia nigra forms the ears while the normal low-signal intensity of superior colliculus forms the mouth of the giant panda [Figure 1].
|Figure 1: (Left) T2-weighted axial magnetic resonance imaging of a 27-year-old female, diagnosed case of Wilson's disease showing the preserved low-signal intensity in red nucleus (eyes), substantia nigra (ears), and superior colliculus (mouth) with increased signal intensity in rest of the tegmentum, forming the classical picture resembling the face of a giant panda. (Right) Image of the face of a panda|
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If the pons is affected, T2-weighted images show relative hypointensity of the central tegmental tracts forming the eyes in contrast with the hyperintensity of the aqueduct opening into the fourth ventricle making up the nose and mouth. The superior cerebellar peduncles form the panda's cheeks. This appearance has been likened to the cub of the panda or the miniature panda sign.
The midbrain and the pons involvement together account for the double-panda sign.
Although it is the basal ganglia which are affected more frequently and earlier in the course of the disease, the characteristic imaging findings are due to the involvement of the midbrain and the pons.
Few conditions such as Leigh disease, hypoxic-ischemic encephalopathy, methanol poisoning, Japanese B encephalitis, and extrapontine myelinolysis can have similar appearances on neuroimaging. In such cases, the characteristic clinical and biochemical features of Wilson's disease can aid in appropriate diagnosis.
The classical neuroimaging signs of Wilson's disease on MRI can be identified in only a small subset of patients, but their presence is a valuable diagnostic clue improving the confidence of the radiologist and helping the clinicians in both making the diagnosis and monitoring the prognosis of these patients.
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Conflicts of interest
There are no conflicts of interest.
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