 5. Performance status: Patients 16 years of age must have a Karnofsky performance level of 70, and children 16 years old must have a Lansky performance of 70 Error! Reference source not found.. Patients who are wheelchair bound because of paralysis secondary to a plexiform neurofibroma should be considered ambulatory when they are up in their wheelchair. Similarly, patients with limited mobility secondary to need for mechanical support such as an airway PN requiring tracheostomy or CPAP will also be considered ambulatory for the purpose of the study. 