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Neuroradiology Case of the Week
Case 439
September 2009
Balasubramanya Kolar, MD and P-L Westesson MD, PhD, DDS
Clinical
Presentation: Patient is a 32-year-old female with gelastic seizures.
Imaging Findings: MR imaging showed a T1 and T2 isointense lesion within the region of hypothalamus more on the right side which was extending inferiorly in the interpeduncular and prepontine cistern.The lesion was nonenhancing on the post-contrast images and the features suggested a tuber cinereum hamartoma.
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Figure 1: Sagittal T1 image shows isointense lesion in the region of hypothalamus extending downwards into the interpeduncular and prepontine cisterns.
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Figure 2: Axial T2-weighted image shows the isointense lesion within the right side of the interpeduncular cistern.
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| Figures 3A&B: Coronal T2 (A) and T1 (B) images show the lesion on the right side extending inferiorly from hypothalamus. |
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Figures 4A & B: Axial (A) and sagittal (B) post-contrast T1-weighted images show absence of enhancement within the lesion. |
Diagnosis: Hypothalamic hamartoma
Discussion: Hypothalamic hamartomas are congenital malformations usually found in patients who present with gelastic seizures or precocious puberty [1]. These lesions are usually sessile or pedunculated in relation to hypothalamus. The imaging features of these lesions include a resemblance or isointensity to gray matter on both T1 and T2 weighted images. There may be hyperintense signal on T2 weighted images also [2].The increased signal on T2 images has been correlated with increasing glial content [3].The main differential diagnosis is a hypothalamic glioma in this region. However, these lesions can be differentiated as hamartomas lack enhancement on post contrast images and there is no increase in size of the lesion on subsequent scans [4].
MR spectroscopy has been studied in these lesions by many authors [2,3,5]. Most of these studies have suggested a reduction in NAA in the form of reduction in NAA/Cr ratios [5] and a few studies have also indicated an increase in myoinositol [3,2]. The increase in mI has also been linked to the glial content [3].There has been variability in the Cho/Cr ratios in different series with some reporting them to be normal [2] and others reporting slight elevation in Cho levels [3].
References:
- Judge DM, Kulin HE, Page R, Santen R, Trapukdi S. Hypothalamic hamartoma: a source of luteinizing-hormone-releasing factor in precocious puberty. N Engl J Med 1977 Jan 6;296(1):7-10. PMID: 318592 [PubMed]
- Freeman JL, Coleman LT, Wellard RM, et al. MR imaging and spectroscopic study of epileptogenic hypothalamic hamartomas: analysis of 72 cases. AJNR Am J Neuroradiol 2004 Mar;25(3):450–62. PMID: 15037472 [PubMed]
- Amstutz DR, Coons SW, Kerrigan JF, Rekate HL, Heiserman JE. Hypothalamic Hamartomas: Correlation of MR Imaging and Spectroscopic Findings with Tumor Glial Content. AJNR Am J Neuroradiol. 2006 Apr;27(4):794-8. PMID: 16611766 [PubMed]
- Valdueza JM, Cristante L, Dammann O, et al. Hypothalamic hamartomas: with special reference to gelastic epilepsy and surgery. Neurosurgery 1994 Jun;34(6):949-58; discussion 958. PMID: 8084405 [PubMed]
- Wakai S, Nikaido K, Nihira H, Kawamoto Y, Hayasaka H. Gelastic seizure with hypothalamic hamartoma: proton magnetic resonance spectrometry and ictal electroencephalographic findings in a 4-year-old girl. J Child Neurol. 2002 Jan;17(1):44-6. PMID: 11913570 [PubMed]
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