Tuberous Sclerosis

Snapshot

• A 6-month-old infant is brought to the emergency department after the parent noticed symmetric and synchronous spasmodic movement of the neck, trunk, and extremities. Hypopigmented area of the skin is notable on physical examination, which can be better visualized on Wood’s lamp. Hypsarrhythmia is seen on EEG.

Introduction

• Tuberous sclerosis
  • neurocutaneous autosomal dominant disease
    • mutation in either TSC1 (encodes hamartin on chromosome 9) and TSC2 (encodes tuberin on chromosome 16) is associated with tuberous sclerosis 
      • normally, hamartin and tuberin form a complex that down regulates mTOR signaling
  • characterized by hamartoma and benign neoplasm development in the brain and various tissues
    • cerebral cortex
      • cortical hamartomas (“tubers”)
        • associated with seizures, which are difficult to control with seizure treatment
        • subependymal astrocytic proliferation
    • retina
      • retinal glial hamartomas
    • heart 
      • cardiac rhabdomyomas
    • renal
      • renal angiomyolipomas 
  • cutaneous manifestations
    • adenoma sebaceum (angiofibromas)
    • hypopigmented macule (ash leaf spot) 
    • shagreen patches
      • patches of localized leathery thickenings
• periungual fibromas

Presentation and Evaluation

• Depending on where benign tumors develop (i.e., brain, heart, skin, etc.), as mentioned above
  • seizure 
    • a frequent and significant cause of morbidity
    • infantile spasm
      • most common type of seizure at initial diagnosis
• hypsarrythmia can be seen on EEG 

Treatment

• Infantile spasms 
  • adrenocorticotropic hormone (ACTH)
    • beneficial in the treatment of infantile spasms in patients with or without tuberous sclerosis
    • how it treats infantile spasm in not fully understood
  • vigabatrin
    • may be effective in the treatment of infantile spasms in patients with tuberous sclerosis
    • believed to irreversibly inhibit GABA transaminase, to increase GABA concentration in the brain
  • ketogenic diet or vagus nerve stimulator
    • can be considered in medically intractable seizures