Neuropathic Pain and Enlarged Nerves in Adult Noonan Syndrome and Noonan Syndrome With Multiple Lentigines: Health‐Related Quality of Life and Neurologic Symptoms

Noonan syndrome (NS) and the clinically related Noonan syndrome with multiple lentigines (NSML) belong to the group of RASopathies. Although pain is not mentioned as a characteristic feature, it has recently been reported as a clinically significant problem. This pain is likely multifactorial in origin, with a significant contribution from neuropathic mechanisms. Patients with NS also have a high chance of having multifocally enlarged nerves, and sometimes show clinical features of neuropathy. The relationship between these nerve findings, pain, health-related quality of life and neurological symptoms remains unclear. This case series aims to provide more insight into the perceived health-related quality of life and neurological symptoms in nine adults with NS or NSML who reported neuropathic pain and had enlarged nerves. Features of some of these patients were already reported in an earlier article. The perceived health-related quality of life was markedly below average. All patients reported somatosensory symptoms consistent with peripheral neuropathy. Six of nine patients reported muscle weakness. Sensory testing was abnormal in five patients, but muscle strength was normal in all patients. Electrodiagnostic testing was consistent with peroneal neuropathy in one patient, muscle and nerve ultrasound imaging confirmed neuromuscular involvement in five of the six patients who reported muscle weakness. No muscle ultrasound imaging was performed in the sixth patient. This study thus shows that adults with NS and NSML with neuropathic pain and enlarged nerves have a significantly impaired perceived health-related quality of life with a variable clinical neurologic phenotype.