NF is an extremely variable disorder. The severity of NF ranges from extremely mild cases in which the only signs of the disorder in adulthood may be multiple café-au-lait spots and a few dermal neurofibromas, to more severe cases in which one or more serious complications may develop. The complications of NF are discussed below. There is no way to predict who will have a mild case and who will develop serious complications. The majority of people with NF (probably 60%) have mild forms of the disorder. Another 20% have correctable problems and another 20% have serious and persistent problems. Many of the serious problems in NF mentioned below are evident at birth or develop prior to adolescence. These may include congenital defects of the bone, scoliosis, optic glioma and neurological impairment leading to learning disabilities. People with NF who have reached adulthood without having these problems are unlikely to develop them.

Complications of NF1

Affects on physical appearance
NF1 can result in changes to the physical appearance in a number of ways. Skin neurofibromas may develop on the face or on exposed areas of the arms or legs. The generally larger and deeper plexiform neurofibromas may grow around the eye or eyelid, or affect growth of one side of the face. Scoliosis, or curvature of the spine (see below), can affect appearance when it is severe. Growths can occur around the nipple (periareolar neurofibromas) which may be distressing. Rarely, an overgrowth of skin or bone causes enlargement of an arm or leg.

In some people, the size or number of neurofibromas increases during puberty and pregnancy, reflecting a possible hormonal effect.

There is no evidence that diet, exercise or vitamins affect the growth of neurofibromas.

While the skin and physical manifestations are often major concerns for those with NF1, not everyone reacts the same way to complications that affect appearance. Some people find that café-au-lait spots or a minimum number of skin neurofibromas are hard to live with, while others are able to tolerate more severe involvement. Those who are upset by the problems of disfigurement often find support and discussion groups to be helpful. If surgery is desired, primarily to improve appearance, a plastic surgeon may be consulted to determine whether a particular tumour can be removed. Plexiform neurofibromas around the eye are often managed jointly by an eye (ophthalmic) surgeon and a plastic surgeon.

Lateral curvature of the spine, known as scoliosis, affects about 20% of people with  NF1. In most cases it is mild and does not require surgery. More severe forms of scoliosis usually appear in early childhood (5-10 years). The milder forms appear during the adolescent growth spurt. A child with scoliosis will need periodic spine X-rays and physical examinations to determine whether corrective measures are needed. In some cases, a brace may be used to prevent progression of the problem. More serious cases may require corrective surgery.

Learning Disabilities
Learning disabilities, often first noticed when the child starts school, are specific problems with reading, writing and the use of numbers which occur in children who have intelligence within the normal range. Learning disabilities are more common in children with NF1 than in other children, and may be associated with hyperactivity. A child suspected of having a learning disability should be evaluated by a psychologist, child neurologist or professional with special knowledge of this problem. Many school systems provide referrals to specialists in these fields. About 6% of children with NF1 have intellectual delay with IQ scores falling below the normal range (less than 70).

Large Heads
About 50% of children and adults with NF1  have large head circumference, which usually does not indicate any significant medical problem. Very rarely, large head circumference results from hydrocephalus, a serious problem which may require surgery. This is usually associated with accelerated growth of the head, and if this occurs,  imaging of the brain with CT scan or MRI can help determine if head enlargement is serious or not. Only a few patients with NF1 will need to have a brain scan because of increasing head circumference. Head circumference in children with NF1 should be measured periodically to monitor that head growth is occurring at an appropriate rate.

Short stature

About 30% of children and adults will have short stature relative to other family members. This is usually only mild and usually does not require therapy.
Optic Gliomas
An optic glioma is a tumour of the optic nerve (the nerve which controls vision). These tumours become symptomatic in 5-7% of children with NF1,  usually appear in childhood and may be  first noticed because of poor or failing vision, bulging of the eye, or rapid increase in height. On the other hand, many children who have optic gliomas remain asymptomatic. Children with NF1 should have routine eye examinations by an ophthalmologist, neurologist or physician familiar with this problem. Treatment for this condition in childhood usually involves chemotherapy. Surgery is very occasionally necessary, and radiotherapy  should be generally avoided for optic gliomas because of late side effects of the treatment, including delays in cognative development and increase risk of damage to blood vessels.

Congenital Defects of Bone
The variety of bone defects seen in NF1 are usually evident at birth. Most are uncommon and affect 1-3% of children. Defects can occur in almost any bone, but are seen most often in the skull and limbs. They include:

Congenital absence of the orbital wall, the bone normally surrounding the eye. Its absence may cause slight bulging of the skin around the eye. This is usually associated with a local plexiform neurofibroma.
Bowing of the leg bones below the knee (tibia or fibula). These bones may be thinner than normal and bowed. If a fracture occurs, healing may be slow or incomplete. Incomplete healing, called pseudoarthrosis, may also affect the bones in the forearm (radius or ulna), but this occurs very rarely. This is a difficult problem, which requires the supervision of an orthopaedic surgeon, and may require both surgery and medical intervention to improve bone formation.

High Blood Pressure (Hypertension)
People with NF1 can have hypertension for reasons completely unrelated to NF1. However, two rare problems associated with NF1 may result in hypertension: renal artery stenosis (narrowing of the artery to the kidney), and pheochromocytoma, a rare and usually benign tumour of the adrenal gland. Both of these problems are treatable. Because of these possible problems, it is important that routine physical exams for children and adults with NF1 include blood pressure checks.

Rare Complications of NF1
The complications mentioned below occur in 1%, or less, of people with NF1. The listing is intended to inform you of the rare complications possible in NF1, but it should be emphasized that very few people with NF1 will experience any of these symptoms.

  • Early or late onset of puberty
  • Epilepsy (seizure disorder)
  • People with NF1 may have a somewhat higher risk for certain rare malignant tumours that occur in the brain, nerves or spinal cord (known as malignant peripheral nerve sheath tumours or MPNSTs), but probably have the same risk for “common” cancers (such as lung, breast, stomach, etc.) as the general population
  • Brain tumours (other than optic glioma)
  • Cerebrovascular occlusion (stroke). This refers to blockage of the blood vessels supplying the brain
  • Hormonal Effects on Neurofibromatosis

A number of patients request information on the effects of hormones on the symptoms of NF. There have been numerous reports of worsening of symptoms as patients experience the hormonal changes associated with puberty. In addition, patients report increases in the number and size of neurofibromas during pregnancy. Changes may also occur as a patient enters menopause. Patients wonder about the effects of birth control pills or hormone replacement therapy on their NF symptoms. There has NOT been a systematic research study to accurately describe or quantify the effect of hormones on tumours or other symptoms of NF. If you experience any changes and are concerned about the role hormones may play in your specific case of NF, you should discuss these concerns with your physician or contact a nearby NF Clinic.

Information and content provided courtesy of The Children’s Tumor Foundation