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The phakomatoses refer
to a variety of neurocutaneous syndromes.1 Almost all are
multisystem disorders that are embryonal in origin. Neurofibromatosis
type 1 and tuberous sclerosis complex are the most common phakomatoses. These
disorders are also discussed in Chapter 182.
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Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominant
disorders in humans, with an estimated incidence of approximately
1 in 3000 live births. It has diverse manifestations in tissues
that are primarily, although not exclusively, of neural crest origin.
Clinical findings form the basis of the National Institutes of Health
Consensus Statement of diagnostic criteria for neurofibromatosis
type 1 (Table 578-1).2 The
diagnostic criteria are met in an individual if 2 or more of the
features listed are present. Clinical, molecular and management
aspects of neurofibromatosis 1 are discussed in Chapter 182.
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Optic pathway gliomas are the main central nervous system tumor
with a marked increased frequency in neurofibromatosis type 1. Because
of their growth, it is recommended that all children age 10 years
or younger with neurofibromatosis type 1 undergo annual ophthalmologic
examinations. When they progress, visual symptoms are produced because
the tumors enlarge and put pressure on the optic nerves-chiasm resulting in
impaired visual acuity and visual fields. Extension into the hypothalamus
can lead to endocrine deficiencies or failure to thrive.
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Although more than 50% of individuals with neurofibromatosis
type 1 will have only cutaneous neurofibromas, café au
lait spots, or Lisch nodules, an estimated 30% to 40% will
develop 1 or more of the serious complications in their lifetime.
The major categories of these complications are malignancy, learning
disability, cerebrovascular disease, hypertension, and scoliosis.
Because of the diverse and unpredictable complications associated
with neurofibromatosis type 1, close multidisciplinary follow-up
is necessary. Patients with neurofibromatosis type 1 should have
regular clinical assessment at least yearly, focusing the history
and examination on the potential problems for which they are at increased
risk. Laboratory tests and imaging studies should be reserved for
investigating specific clinical symptoms and signs. Some of the
routine follow-up recommended includes yearly clinical assessment
with blood pressure monitoring and yearly ophthalmologic examination.
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Tuberous sclerosis complex is an autosomal dominant multisystem disease.
It usually presents with seizures, mental retardation, ...