giovedì 3 novembre 2005

Tuberous sclerosis


There are enhancing subependymal nodules (Figure 3) with the largest having degenerated into a subependymal giant cell astrocytoma (Figure 1 and Figure 2). There are multiple cortical/subcortical tubers seen best on FLAIR images (Figure 4).

Diagnosis: Tuberous sclerosis

Tuberous sclerosis is an autosomal dominant, inherited disorder that affects cell differentiation, proliferation, and migration. The classic clinical triad includes epilepsy, mental retardation, and cutaneous skin lesions. Almost all organ systems are affected including cutaneous, neurologic, ocular, dental, pulmonary, and cardiac.

Diagnostic criteria include major and minor features. Definite diagnosis requires at least 2 major features or 1 major with 2 minors.

Major features include
- facial angiofibromas
- shagreen patches
- ash-leaf spots
- subependymal nodules
- subependymal giant cell astrocytoma
- cardiac rhabdomyoma
- renal angiomyolipoma
- lymphangioleiomyomatosis
- retinal hamartoma
- macules

Minor features include
- dental pits
- renal cysts
- rectal hamartoma polyps
- cerebral white matter migration lines
- gingival fibromas
- confetti skin lesions

Characteristic neurologic findings are present in over 95% of patients diagnosed with tuberous sclerosis. The classic neurologic features are calcified subependymal nodules, subependymal giant cell astrocytomas, cortical and subcortical tubers, and white matter lesions along lines of neuronal migration. Subependymal nodules can progress into subependymal giant cell astrocytomas that can result in obstructive hydrocephalus at the foramen of Monro. Subependymal nodules and subependymal giant cell astrocytomas usually enhance on contrast studies and are often found along the caudothalamic groove. Periodic brain CT or MRI with contrast can be performed in asymptomatic patients to evaluate for development or progression of lesions that may eventually result in obstructive hydrocephalus. MRI fluid-attenuated inversion recovery (FLAIR) sequences are better for evaluation of subcortical and cortical tubers.

Other imaging studies to consider include ultrasound to evaluate for renal angiomyolipomas or renal cysts, as well as cardiac CT or echocardiogram to evaluate for rhabdomyoma.

Treatment mainly focuses on minimizing the patient’s seizure activity by using anti-epileptic medications and a ketogenic diet.

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