Neurofibromatosis type 1 is a disease based on the development of tumors (neurofibromas) from nervous tissue, both in the central nervous system and on peripheral nerves. The symptoms depend on the location of the tumors. The earliest and most typical sign of the disease are pigmented spots larger than 1.5 cm. Diagnosis is carried out on the basis of the clinic and the hereditary nature of the disease. X-ray and tomographic examination methods are used to detect tumors. A specific treatment has not been developed. According to the indications, tumors are removed.
General information
According to observations conducted by clinical dermatology, neurofibromatosis type 1 is most often diagnosed at the age of 3 to 16 years. If there are lesions of the central nervous system, the central form of the disease (NF2) is isolated, and if only peripheral nerves are affected, the peripheral form (NF1) is isolated. Neurofibromatosis type 1 occurs 1 time per 4000 births, and NF2 is much rarer — 1 time per 50,000.
Causes
Neurofibromatoses are hereditary diseases that occur in connection with genetic disorders. Neurofibromatosis type 1 is transmitted autosomally dominant. This means that the probability of having a child with pathology in a sick parent is 50%. In some cases, neurofibromatosis type 1 develops as a result of a spontaneous mutation in a family where cases of this disease have not been previously observed.
Symptoms
The clinical picture of neurofibromatosis type 1is characterized by a significant variety of symptoms. The earliest sign that allows you to suspect a disease is the presence of more than 5 pigmented spots with a diameter of 1.5 cm or more in a newborn or a child. They are usually located on the trunk and neck, but can be on the face and limbs. As a rule, pigmented spots with neurofibromatosis have a milky coffee color, but purple, blue and even depigmented spots can occur.
The peripheral form is characterized by the development of multiple neurinomas of peripheral nerves and neurofibromas in the form of subcutaneous nodules. Tumors can be localized on the trunk, neck, head, limbs. They have a rounded shape, are mobile and painless when probing. The size of such formations is on average 1-2 cm, but in some cases they reach a significant size with a weight of about 2 kg. The skin above the tumors is often more pigmented, hair growth may occur at the top of the formation.
When neurinomas appear on the terminal branches of nerve trunks, it leads to difficulty in lymph outflow and the development of “elephantiasis” (lymphedema), which is manifested by an increase in the volume of the limb, part of the face, and tongue. Often NF1 is combined with anomalies of skeletal development: scoliosis, asymmetry of the skull, non-hardening of the vertebral arches, etc. A specific sign of neurofibromatosis type 1 is the detection of a whitish spot on the patient’s iris — a Lisch nodule. This sign occurs in 94% of patients with NF1.
The central form of neurofibromatosis type 1 is characterized by meningiomas or gliomas affecting spinal roots and cranial nerves, less often localized inside the spinal canal or skull. The symptoms of central nervous system damage depend on the location of the tumor and the degree of compression of the spinal cord or brain. These may be headache, loss of sensitivity, balance disorders, signs of damage to the craniofacial nerves, speech disorders. At the same time, as a rule, there are no violations of motor function.
About a fifth of patients often have a lesion of the visual analyzer, manifested by the development of neurofibromas of the membranes of the eye, glaucoma, exophthalmos, a tumor of the optic nerve. Most often, with NF2, bilateral hearing loss is observed due to the development of neurinomas of both auditory nerves. In some cases, this is the only manifestation of the disease. Disease can be accompanied by mental retardation, epileptic seizures, gynecomastia, premature puberty.
Diagnostics
Pigmented spots of various sizes are found in most children. However, a large number of such spots is a reason to consult a dermatologist. The doctor will examine not only the pigmented formations, but also the whole child to identify other signs of neurofibromatosis type 1. Early diagnosis is the possibility of timely treatment before the development of complications from overgrown tumor formations.
To determine the localization of tumors in neurofibromatosis type 1, CT and MRI of the spine, MRI and CT of the brain are performed. Diagnosis of skeletal abnormalities is carried out by radiography of the spine and skull. In the diagnosis of NF2, a hearing examination is mandatory: audiometry, Weber test, impedancometry, electrocochleography, study of evoked auditory potentials.
Since neurofibromatosis type 1 is associated with damage to the nervous system, a neurologist’s consultation is necessary. If skeletal abnormalities are detected, the patient should be examined by an orthopedist. The decision on surgical treatment is carried out by a neurosurgeon.
Treatment
Unfortunately, to date, medicine does not have effective ways to treat neurofibromatosis type 1. Patients are undergoing symptomatic therapy. With a large size of peripheral tumors, the development of neurological disorders, the appearance of signs of compression of the brain, operations are performed to remove tumors. Neurofibromas can be removed for cosmetic purposes. With their malignancy (3-5% of cases), the removal of the tumor is supplemented with courses of chemotherapy and radiation therapy.
Treatment of hearing disorders is carried out with the use of hearing aids. However, after surgery for the removal of an auditory nerve neurinoma, hearing replacement is possible only with the help of cochlear implantation.
