Neurofibromatosis Type 1 (von Recklinghausen Disease, NF1)

Airway tumors, not skin lesions - Cutaneous neurofibromas are cosmetic. Plexiform neurofibromas are the airway problem: they arise from nerve fascicles, infiltrate surrounding structures, are present from birth and occur in 25% to 30% of patients. A cervicofacial or mediastinal lesion distorts or compresses the airway from outside, and internal neurofibromas are described around the eye, retroperitoneally, along the GI tract and in the mediastinum. These patients already have MRI — read it, along with prior anesthetic records, before you commit to an airway plan.

Pheochromocytoma changes the whole anesthetic - This is the highest-stakes NF1 finding. Catecholamine release produces paroxysmal hypertensive crisis, and an unrecognized tumor turns a routine case into one. Screen when the picture fits — episodic hypertension with palpitations, headache and postural hypotension in a patient with neurofibromatosis stigmata — using plasma or urinary metanephrines, then CT or MRI to localize. A positive screen means the elective case waits for medical optimization and endocrine referral, not a careful induction.

Hypertension has three causes here - There is no single valve lesion that travels with NF1; hypertension is the cardiovascular finding, and it is pheochromocytoma, renovascular disease, or essential. NF1 is among the disorders associated with fibromuscular dysplasia of the renal and craniocervical arteries. Check pressures in both arms and send metanephrines before you write off hypertension in a young NF1 patient as essential.

Vasculopathy and vascular access - NF1 carries a documented vasculopathy alongside its bone and cognitive features, and the craniocervical vessels can be dysplastic. Factor that into arterial and central line placement, and use ultrasound rather than landmarks.

Scoliosis and the chest - Scoliosis and long bone dysplasia are part of the syndrome, and severe NF1-associated curves are described. In a child, early-onset scoliosis restricts a thorax and lungs that are still developing, so the curve is a respiratory question as much as a positioning one. Look at the most recent spine films and at exercise tolerance before a long prone case.

Positioning around fragile bone - Long bone dysplasia and congenital pseudarthrosis of the tibia, which is associated with NF1, mean a limb may already be deformed or fragile. Support and pad the affected limb rather than forcing it into a standard frame.

Document neurology before you block - Plexiform neurofibromas, spinal deformity and malignant transformation all produce baseline deficits. Record the motor and sensory exam preoperatively so a postoperative deficit is not attributed to your regional block or your positioning.

Malignant transformation - Plexiform neurofibromas carry an 8% to 13% risk of becoming a malignant peripheral nerve sheath tumor. The warning signs are pain lasting more than a month, a new neurologic deficit, a lesion turning from soft to hard, or rapid growth. If the plan is wide local excision of a plexiform lesion, expect a longer and larger case than the skin suggests.

Ask what treatment they are on - Optic glioma occurs in about 15%, and there is increased risk of rhabdomyosarcoma and myeloid leukemia. Chemotherapy is first-line for optic glioma and imatinib is used to shrink plexiform neurofibromas, so recent myelosuppression is worth a CBC before an elective case.

Learning difficulty and ADHD - Both are part of NF1, and cognitive dysfunction has been associated with the T2 bright spots and megalencephaly seen on brain MRI. Plan the induction around it — premedication and a caregiver present beats an argument at the door.

Do not import NF2 assumptions - These are different diseases. NF1 is linked to unilateral acoustic neuroma; bilateral vestibular schwannoma, meningioma and the raised intracranial pressure that goes with them belong to NF2. Lisch nodules, present in 90% to 100% of NF1 adults over 20, do not affect vision and do not affect your anesthetic.

Neurofibromatosis type 1 (NF1), or von Recklinghausen disease, is an autosomal dominant loss-of-function mutation in the NF1 gene at 17q11.2, which encodes neurofibromin — a GTPase-activating protein that normally restrains the RAS pathway. Lose it and RAS/MAPK and mTOR signaling run unchecked, driving tumors along nerve sheaths. Prevalence is about 1 in 2,600 to 3,000; penetrance is complete but expressivity varies widely, and half of cases are sporadic. NF1 accounts for roughly 96% of all neurofibromatosis.

What matters at the board is that this is a tumor and vasculopathy syndrome rather than a skin one. Plexiform neurofibromas arise from nerve fascicles and infiltrate surrounding structures; scoliosis and long bone dysplasia deform the spine and chest; the arteries are dysplastic; and there is a real, anesthetic-changing association with pheochromocytoma.