Neurology · MU Sofia

82. Phakomatoses

Explains the hereditary neurocutaneous phakomatoses, first defining the group by its skin, nervous system, eye and blood vessel involvement and its embryonic origin. It then goes through neurofibromatosis types 1 and 2, tuberous sclerosis complex, Sturge-Weber syndrome and von Hippel-Lindau disease, giving genetics, clinical features and a diagnostic clue for each. Closing sections cover neurological manifestations, diagnostic investigations and the symptomatic, surgical and surveillance approach to treatment.

Inside: 4 sections · 8 labelled pictures · 16 flashcards · 2 min

Topic 82 of 88 in the MU Sofia syllabus for Neurology (Medicine, Year 4). The free AceMed note covers it in 4 sections, about 286 words (2 min of reading), with 16 flashcards.

In this note

  1. Phakomatoses
  2. Major Phakomatoses
  3. Diagnosis
  4. Treatment

Phakomatoses

Definition: Phakomatoses are a group of hereditary neurocutaneous disorders characterized by abnormalities of the:

  • Skin. Nervous system. Eyes. Blood vessels

They result from defects in embryonic ectodermal development and are associated with tumor formation and neurological complications.

Major Phakomatoses

1. Neurofibromatosis Type 1 (NF1)

Genetics: Autosomal dominant. Mutation of NF1 gene (chromosome 17)

Clinical Features

  • Skin: Café-au-lait spots (>6). Axillary/inguinal freckling
  • Nervous System: Multiple neurofibromas. Plexiform neurofibromas. Learning difficulties
  • Eye: Lisch nodules (iris hamartomas)
  • Other: Scoliosis. Optic pathway glioma

Diagnostic Clues: Café-au-lait spots + neurofibromas

2. Neurofibromatosis Type 2 (NF2)

Genetics: Autosomal dominant. Mutation of NF2 gene (chromosome 22)

Clinical Features

  • Hallmark: Bilateral vestibular schwannomas
  • Symptoms: Progressive hearing loss. Tinnitus. Balance disturbances
  • Other Tumors: Meningiomas. Ependymomas

Diagnostic Clue: Bilateral vestibular schwannomas

3. Tuberous Sclerosis Complex (TSC)

Genetics: Autosomal dominant. TSC1 or TSC2 mutation

Clinical Features

  • Skin: Facial angiofibromas (adenoma sebaceum). Hypomelanotic “ash-leaf” spots. Shagreen patches
  • CNS: Epilepsy (very common). Intellectual disability. Cortical tuber
  • Other Organs: Renal angiomyolipomas. Cardiac rhabdomyomas

Diagnostic Clue: Epilepsy + facial angiofibromas + ash-leaf spots

4. Sturge-Weber Syndrome

Pathology: Congenital vascular malformation

Clinical Features

  • Skin: Port-wine stain in trigeminal distribution
  • CNS: Seizures. Hemiparesis. Intellectual disability
  • Eye: Glaucoma

Diagnostic Clue: Port-wine stain + seizures

5. Von Hippel-Lindau Disease

Genetics: Autosomal dominant. VHL gene mutation

Clinical Features

  • CNS: Cerebellar hemangioblastomas. Spinal hemangioblastomas
  • Eye: Retinal angiomas
  • Other: Renal cell carcinoma. Pheochromocytoma

Diagnostic Clue: Hemangioblastomas + renal tumors

Neurological Manifestations of Phakomatoses: Epilepsy. Intellectual disability. Headache. Focal neurological deficits. Cranial nerve dysfunction. Brain and spinal tumors

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