Periodic limb movement disorder (PLMD) is a sleep disorder where the patient moves limbs involuntarily and periodically during sleep, and has symptoms or problems related to the movement. PLMD should not be confused with restless legs syndrome (RLS). RLS is characterized by a voluntary response to an urge to move legs due to discomfort. PLMD on the other hand is involuntary, and the patient is often unaware of these movements altogether. Periodic limb movements (PLMS) occurring during daytime period can be found but are considered as a symptom of RLS. Only PLMS during sleep can suggest a diagnosis of PLMD.Periodic limb movement disorder is characterized by recurrent episodes of frequent limb movements while sleeping. It mostly happens in the lower parts of the body like the toes, ankles, knees and hips. It can also, in some cases, appear in the upper extremities of the body. These movements can lead the patient to wake up, and if so, sleep interruption can be the origin of excessive daytime sleepiness.PLMD is characterized by increased periodic limb movements during sleep (PLMS), which must coexist with a sleep disturbance or other functional impairment, in an explicit cause-effect relationship. Usually, these involuntary movements come from lower extremities (including toes, ankles, knees, and hips), although they can also be observed in upper extremities, occasionally. PLMS seem to be common features within many people, and identifying whether or not these movements are clinically relevant for a distinct diagnosis of PLMD remains a challenge for clinical and scientific fields.
Approximately 25% of patients will require corrective surgery.Skeletal muscle weakness and motor control deficits
Deficits in motor function in NF-1 have been long recognised and have been historically attributed to nerve dysfunction. In recent years however, studies suggest NF-1 is associated with a primary problem in muscle function (myopathy).Clinical findings in people with NF-1 include:

Reduced skeletal muscle size
Reduced exercise capacity
Muscle weakness (The most recent study reports between 30–50% reduced upper and lower limb muscle strength in NF-1 children compare with matched controls).Studies in genetically modified mice have thus far confirmed that the NF1 gene is vital for normal muscle development and metabolism. Knockout of the NF1 gene in muscle results in deregulated lipid metabolism and muscle weakness.NF-1 is a disease in the RASopathy family of diseases, which include Costello Syndrome, Noonan Syndrome, and Cardiofaciocutaneous syndrome. The RASopathies also present with skeletal muscle weakness. It is likely that impaired muscle function in these disorders is linked to altered Ras/MAPK signalling, however, the precise molecular mechanisms remain unknown. Facial bones and limbs
Bowing of a long bone with a tendency to fracture and not heal, yielding a pseudarthrosis. The most common bone to be affected is the tibia, causing congenital pseudarthrosis of the tibia or CPT. CPT occurs in 2–4% of individuals with NF-1. Treatment includes limb amputation or correction by Ilizarov method as a limb-sparing technique. Malformation of the facial bones or of the eye sockets (lambdoid suture defects, sphenoid dysplasia)
Unilateral overgrowth of a limb.