Neurofibromatosis type 1 and type 2 both occur in mosaic forms. Mosaicism results from somatic mutations. Early somatic mutations cause generalized disease, clinically indistinguishable from nonmosaic forms. Later somatic mutation gives rise to localized disease often described as segmental. In individuals with mosaic or localized manifestations of neurofibromatosis type 1 (segmental neurofibromatosis type 1), disease features are limited to the affected area, which varies from a narrow strip to one quadrant and occasionally to one half of the body. Distribution is usually unilateral but can be bilateral, either in a symmetric or asymmetrical arrangement. Patients with localized neurofibromatosis type 2 have disease-related tumors localized to one part of the nervous system; for example a unilateral vestibular schwannoma with ipsilateral meningiomas or multiple schwannomas in one part of the peripheral nervous system. The recognition of mosaic phenotypes is important. Individuals with the mosaic form, even with a generalized phenotype, are less likely to have severe disease. They also have lower offspring recurrence risk than individuals with the nonmosaic form. The mosaic forms of neurofibromatosis provide a good example of the effects of somatic mutation. It is increasingly recognized that mild and unusual forms of many dominantly inherited disorders are caused by the same mechanism.

Since its first clinical description (on his son) by William James West (1793–1848) in 1841, and the definition of the classical triad of (1) infantile spasms; (2) hypsarrhythmia, and (3) developmental arrest or regression as “West syndrome”, new and relevant advances have been recorded in this uncommon disorder. New approaches include terminology of clinical spasms (e.g., infantile (IS) vs. epileptic spasms (ES)), variety of clinical and electroencephalographic (EEG) features (e.g., typical ictal phenomena without EEG abnormalities), burden of developmental delay, spectrum of associated genetic abnormalities, pathogenesis, treatment options, and related outcome and prognosis. Aside the classical manifestations, IS or ES may present with atypical electroclinical phenotypes (e.g., subtle spasms; modified hypsarrhythmia) and may have their onset outside infancy. An increasing number of genes, proteins, and signaling pathways play crucial roles in the pathogenesis. This condition is currently regarded as a spectrum of disorders: the so-called infantile spasm syndrome (ISs), in association with other causal factors, including structural, infectious, metabolic, syndromic, and immunologic events, all acting on a genetic predisposing background. Hormonal therapy and ketogenic diet are widely used also in combination with (classical and recent) pharmacological drugs. Biologically targeted and gene therapies are increasingly studied. The present narrative review searched in seven electronic databases (primary MeSH terms/keywords included West syndrome, infantile spasms and infantile spasms syndrome and were coupled to 25 secondary clinical, EEG, therapeutic, outcomes, and associated conditions terms) including MEDLINE, Embase, Cochrane Central, Web of Sciences, Pubmed, Scopus, and OMIM to highlight the past knowledge and more recent advances.

Background: Neurofibromatosis type 2 (NF2) is an autosomal dominant disease characterised by the development of multiple nervous system tumours, ocular abnormalities, and skin tumours. Although classically considered a disease of adults, initial signs and/or symptoms may be evident in childhood and are often unrecognised. Objectives: The aim of this study was to identify the earliest clinical presentations of NF2 and to characterise the clinical course and outcome in children with NF2. Methods: We have performed a retrospective (years 1990 - 1998) and prospective (years 1998 - 2004) study of 24 patients (10 males, 14 females; currently aged 4 to 22 years) fulfilling the revised (Manchester) NF2 criteria seen at the Universities of Catania and Rome, Italy. Results: Causes of referral prior to a definitive diagnosis of NF2 were: 1) Ophthalmologic problems: early onset lens opacities (n = 3); strabismus (n = 3) and amblyopia (n = 3) (due to underlying cranial nerves and/or brain tumours); 2) Otolaryngology problems: hearing loss and tinnitus (n = 2) in early teens disregarded or treated as ear infections; hoarse (n = 1) or bitonal (n = 1) voice; 3) Neurological dysfunction: seizures secondary to intracranial meningioma (n = 1) or vestibular schwannomas (VS) (n = 1), neurological dysfunction related to brainstem and/or spinal cord tumours (n = 7), isolated and multiple cranial nerve deficits (n = 10), and peripheral neuropathy secondary to schwannomas (n = 4); 4) Skin manifestations: schwannomas misdiagnosed as neurofibromas because of associated café-au-lait spots (n = 2); café-au-lait spots (n = 8) and skin tumours (n = 3). A family history was relevant in 20 % of the patients. Molecular genetic analysis of the NF2 gene revealed typical truncating mutations in all the 5 familial cases and in 2/10 sporadic cases analysed. Conclusions: Children with NF2 often first come to medical attention because of ocular, subtle skin, or neurological problems the significance of which is realised when they later present with more classical symptoms due to bilateral VS or other intracranial tumours. The clinical course at this young age is highly variable, depending on tumour burden, early surgical intervention, surgical outcome after tumour resection, and complications. 1 This work was done at the Departments of Pediatrics, University of Catania and Division of Child Neurology, Department of Pediatrics, University of Rome “La Sapienza”, Italy. Presented in part at the 5th European Pediatric Neurology Society (EPNS) Meeting held in Taormina, Italy, 22 - 25 October 2003 (Eur J Pediatr Neurol 2003; 7: 359)