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NEUROIMAGING
Year : 2012  |  Volume : 7  |  Issue : 1  |  Page : 27-29
 

Magnetic resonance imaging in pantothenate kinase-2-associated neurodegeneration


Department of Radiodiagnosis, Dayanand Medical College and Hospital, Ludhiana, Punjab, India

Date of Web Publication28-Jun-2012

Correspondence Address:
Paramdeep Singh
Department of Radiodiagnosis, Dayanand Medical College and Hospital, Ludhiana, Punjab
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1817-1745.97618

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   Abstract 

Pantothenate kinase-2-associated neurodegeneration (PKAN) is a rare autosomal recessive pediatric neurodegenerative disorder characterized by rigidity, dystonia, impaired postural reflexes, and progressive dementia. On T2-weighted magnetic resonance imaging images, marked low signal intensity is seen in the globus pallidus. This low signal intensity surrounds a central region of high signal intensity in the anteromedial globus pallidus, giving an eye-of-the-tiger appearance.


Keywords: Eye of the tiger, MRI, Pantothenate kinase-2-associated neurodegeneration


How to cite this article:
Singh P, Saggar K, Kaur M, Pannu DS. Magnetic resonance imaging in pantothenate kinase-2-associated neurodegeneration. J Pediatr Neurosci 2012;7:27-9

How to cite this URL:
Singh P, Saggar K, Kaur M, Pannu DS. Magnetic resonance imaging in pantothenate kinase-2-associated neurodegeneration. J Pediatr Neurosci [serial online] 2012 [cited 2019 Jun 26];7:27-9. Available from: http://www.pediatricneurosciences.com/text.asp?2012/7/1/27/97618


A 14-year-old boy presented with chief complaints of progressively increasing abnormal movements, gait disturbances, speech difficulty, and intellectual decline since the age of 10 years. He was born at full term to consanguineous parents. No history of perinatal hypoxic insult or delayed milestones was present. No relevant family history was present. Neurological examination revealed a generalized increase in limb tone, dsytonia, and hyperreflexia with extensor planter responses. Ophthalmic evaluation was normal. No evidence of  Kayser-Fleischer ring More Detailss or retinitis pigmentosa was seen. Serum copper, iron, and ceruloplasmin levels were within normal limits. Blood smear was positive for acanthocytes.

Magnetic resonance imaging (MRI) of brain revealed bilateral anteriomedial hyperintensity surrounded by a region of hypointensity in the medial globus pallidus on T2- and T2*-weighted images (eye-of-the-tiger sign). Similar hypointensity was also seen in dentate nuclei, red nuclei, and substantia nigra [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5] and [Figure 6].
Figure 1: Axial T2-weighted image showing hypointensity (thick arrow) with a central region of hyperintensity (thin arrow) in the medial globus pallidus (eye-of-the-tiger sign)

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Figure 2: Axial T2-weighted image showing hypointense signal localized in the dentate nuclei of the cerebellum (arrow)

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Figure 3: Axial T2-weighted image showing hypointense signal in the substantia nigra and red nuclei (arrow)

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Figure 4: T2* weighted image showing hypointensity with a central region of hyperintensity in the medial globus pallidus (eye-of-the-tiger sign)

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Figure 5: T2* weighted image showing hypointense signal localised in the dentate nuclei of the cerebellum

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Figure 6: T2* weighted image showing hypointense signal in the substantia nigra and red nuclei

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Neurodegeneration with brain iron accumulation (NBIA) is a clinically and genetically heterogenous group of disorders characterized by brain iron deposition and associated with neuronal death. The causes of NBIA comprise pantothenate kinase-associated neurodegeneration (PKAN), neuroferritinopathy, infantile neuroaxonal dystrophy, and aceruloplasminemia. [1] PKAN is a rare autosomal recessive neurodegenerative disorder. The diagnosis is usually made in first decade of life or in early adolescence. The clinical phenotype that is associated with mutations in the pantothenate kinase 2 gene, PANK2, is termed pantothenate kinase-associated neurodegeneration (PKAN) and is usually classified into classical or atypical forms. Classic PKAN is characterized by early age of onset, usually before 6 years, and rapid progression. The main clinical (extrapyramidal) features are dystonia, speech disturbance (dysarthria), and rigidity, with corticospinal tract involvement resulting in spasticity, hyperreflexia, and extensor planter responses. Patients with atypical PKAN have a later onset of symptoms and progression is slower. The average age of onset is 13-14 years. Iron levels in CSF and blood are within normal limits. [2] Neuroferritinopathy and aceruloplasminemia present in adult or late life. [1] Iron deposition abnormalities are also seen in non-inherited disorders such as in beta-thalassemia major, HIV and Wilson disease, where T2* hypointensities of the globus pallidus, caudate nuclei, and putamen have been described.

The substantia nigra, dentate nuclei, and globus pallidus are iron-rich structures in the normal brain. The main MRI features associated with NBIA is due to high iron in the basal ganglia, appreciated as hypointense lesions in the globus pallidus and substantia nigra pars reticulata on T2-weighted images. A central region of hyperintensity with surrounding hypointensity of the globus pallidus on T2-weighted images (eye-of-the-tiger sign) is nearly pathognomonic for PKAN [Figure 1]. The hyperintense central region indicates edema or necrosis, while the surrounding hypointense region indicates high iron. [2] Pathological analysis of brain tissue from patients with PKAN shows triad of iron deposition, axonal spheroids, and gliosis in the globus pallidus. [3] The central hyperintensity seen in PKAN is absent in non-PKAN forms of NBIA; the MRI demonstrates only hypointense signal in the globus pallidus on T2-weighted images. [4] An eye-of-the-tiger sign, considered almost pathognomonic of PKAN, has been observed in cases of neuroferritinopathy. Eye-of-the-tiger sign can be seen in non-NBIA conditions such as corticobasal degeneration and progressive supranuclear palsy, and these should be considered in the differential diagnosis. This sign has also been reported in other extrapyramidal parkinsonian disorders, including cortical-basal ganglionic degeneration, Steele-Richardson-Olszewski syndrome, and early-onset levodopa-responsive  Parkinsonism More Details. [1],[5]

Thus, an eye-of-the-tiger sign must not be interpreted in isolation; scans should be looked for involvement of other basal ganglia nuclei and cerebral cortex.

 
   References Top

1.McNeill A, Birchall D, Hayflick SJ, Gregory A, Schenk JF, Zimmerman EA, et al. T2* and FSE MRI distinguishes four subtypes of neurodegeneration with brain iron accumulation. Neurology 2008;70:1614-9.  Back to cited text no. 1
[PUBMED]  [FULLTEXT]  
2.Gregory A, Hayflick SJ. Neurodegeneration with brain iron accumulation. Folia Neuropathol 2005;43:286-96.  Back to cited text no. 2
[PUBMED]  [FULLTEXT]  
3.Halliday W. The nosology of Hallervorden-Spatz disease. J Neurol Sci 1995;134:84-91.  Back to cited text no. 3
[PUBMED]  [FULLTEXT]  
4.Hayflick SJ, Hartman M, Coryell J, Gitschier J, Rowley H. Brain MRI in neurodegeneration with brain iron accumulation with and without PANK2 mutations. AJNR Am J Neuroradiol 2006;27:1230-3.  Back to cited text no. 4
[PUBMED]  [FULLTEXT]  
5.Guillerman RP. The eye-of-the-tiger sign. Radiology 2000;217:895-6.  Back to cited text no. 5
[PUBMED]  [FULLTEXT]  


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]



 

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