Tuberous Sclerosis: Magnetic Imaging of the Brain

Abstract

The results of the magnetic resonance imaging of three patients with proven tuberous sclerosis will be discussed. Cortical tubers and subcortical areas of junctional dysmyelination can be demonstrated clearly by MRI, whereas small calcifications may be missed because of low contrast if the chosen slice thickness should be too large. It is suggested that MRI should be applied to those patients with suspected tuberous sclerosis, in which CT has failed to demonstrate typical subependymal calcifications and to those in which doubts about the definite diagnosis remain. This should be done in order to improve the accuracy of genetic counselling. It may be argued that all patients with tuberous sclerosis have to be referred to MRI, because transformation of subependymal nodules into diffusely infiltrating gliomas can be detected earlier if comparison with a former MRI study is possible.

Topographic Comparative Study of Magnetic Resonance Imaging and Electroencephalography in 34 Children with Tuberous Sclerosis

“…Second, tubers may go undetected because of the variable proportion of astrocytes and neurons (Martin et al, 1987); epileptogenicity may therefore also be different. Third, heterotopic clusters of giant cells in the white matter have also been reported in TS (Martin et al, 1987;Terwey and Doose, 1987); their radial location between ventricle and cortex forming a continuous line between ependyma and tuber recalls the embryologic migration of the spongioblasts (Donegani et al, 1972). Lack of a portion of the normal neuronal population in the corresponding cortical area could explain epilepsy in patients without a corresponding MRI highintensity signal area.…”

“…, 1986;Kingsley et d., 1986;Martin et al, 1987;McMurdo et al, 1987;Roach et al, 1987;Terwey and Doose, 1987;Altman et al, 1988). Cortical tubers may represent the epileptogenic foci in TS.…”

Tuberous Sclerosis in the Elderly

“…The most characteristic changes are periventricular calcifications, particularly around the foramina of Monro, with proximal ventricular enlargement (see Figure 2). 14 MR findings are present in 98% of those with tuberous sclerosis and are characterized by multiple high‐signal lesions in the cerebral cortex, which are only occasionally seen on CT scan 13,15,16 . The parenchymal lesions may appear as low‐signal lesions if they have large amount of calcification (see Figure 3).…”

“…The parenchymal lesions may appear as low‐signal lesions if they have large amount of calcification (see Figure 3). 16 When CT and MR are compared, MR is superior in identifying more lesions, but CT is superior in identifying the small diagnostic periventricular calcifications; therefore, CT appears to be a better method of screening elderly patients for tuberous sclerosis 17…”

Magnetic Resonance Imaging

“…vocate routine CT scans every 2 to 3 years to detect the development of this tumor (and resulting hydrocephalus) as early as possible.55,65 MRI may be a better choice. 66 Although further investigation is needed, MRI appears to be as sensitive as CT in distinguishing giant cell astrocytoma from benign subependymal nodule.14 Gd-DTPA enhancement is helpful. 35,67 Early diagnosis of tuberous sclerosis is important for genetic counseling and prognostic purposes.68 The likeli¬ hood of finding tuberous sclerosis in a parent of an affect¬ ed child depends in part on the completeness of evalua¬ tion.52 Before genetic counseling is provided, CT is often used in the phenotypic evaluation of parents, since a sig¬ nificant proportion of "normal" parents of affected chil¬ dren actually represent forme fruste versions oftuberous sclerosis.69 Because of the superior sensitivity and lack of ionizing radiation, MRI may become a valuable screening tool for genetic counseling.55,66 In some parents, MRI may substantiate the diagnosis of tuberous sclerosis when the CT scan is normal.52,70 Studies directly comparing CT and MRI will be required to determine their relative useful¬ ness in the investigation of parents for tuberous sclerosis.…”