Whereas other syndromes such as Noonan syndrome with multiple lentigines, for instance, do not. In cases where conditions that do not have diagnostic criteria are suspected, genetic testing is more likely to be necessary. Diagnostic criteria are not perfect as sensitivity and specificity is not 100%. Similarly, genetic testing can produce false negatives. For example, genetic testing is positive in only 75-90% of cases of tuberous sclerosis complex. Thus, clinicians must apply clinical judgement when evaluating an individual suspected to have a neurocutaneous syndrome. Treatment
The treatment of each neurocutaneous syndrome is unique. For some neurocutaneous syndromes such as neurofibromatosis 1 and tuberous sclerosis complex there are guidelines with recommendations for surveillance and management. For less common syndromes such guidelines are not yet available. Surveillance is a necessity for many neurocutaneous syndromes because new manifestations may develop over time which may only be detected with specific and focused testing. Thus, patients may be advised to obtain particular evaluations (e.g., MRI, ophthalmologic or dermatological examinations) within recommended intervals over time with the aim of detecting new manifestations of the syndrome early on. Most of the currently available treatments for neurocutaneous syndromes do not address the underlying genetic cause. For example, epilepsy surgery in tuberous sclerosis complex or vestibular schwannoma surgery in neurofibromatosis type 2. However, there are some treatments that do address the underlying cause such as the use of mTOR inhibitors in tuberous sclerosis complex.
They can also less commonly present with dizziness or balance impairment. It is estimated that schwannomas occur in over 90% of patients.Meningiomas are the second most common tumor in NF2. Approximately half of patients have an intracranial meningioma and extramedullary spinal meningiomas occur in one-fifth of patients. Relative to the general population, meningiomas in NF2 tend to occur at a younger age, are more likely to be multiple and are associated with increased mortality.Spinal cord ependymomas occur in 20-50% of patients but they are asymptomatic in the majority of cases. In cases that they are symptomatic the specific presentation will depend upon where they are located. Potential symptoms include back pain, weakness and sensory changes. Peripheral neuropathy eventually occurs in most patients with NF2. In some cases, a mononeuropathy affecting the facial nerve can occur as the first presenting symptom of NF2. Other potential manifestations include focal amyotrophy, mononeuropathy multiplex or a severe generalized polyneuropathy in 3-5% of patients.Ophthalmologic manifestations are also common with 60-80% of patients developing cataracts. Optic nerve meningiomas and retinal hamartomas can result in vision loss. Approximately, 70% of patients will have cutaneous manifestations but only 10% have more than 10 lesions. The majority of skin lesions are schwannomas but neurofibromas can also occur. Tuberous sclerosis (Bourneville syndrome)
Tuberous sclerosis complex (TSC) is a multisystemic disorder due to autosomal dominant mutations in either TSC1 or TSC2 which results in the impaired inhibition of the mechanistic target of rapamycin (mTOR) signaling pathway.