[West's syndrome. Analysis, aetiological factors and therapeutic options]

West's syndrome (WS), which is also known as infantile myoclonic encephalopathy with hypsarrhythmia, is one of the generalized epileptic syndromes with a cryptogenic or symptomatic origin. It is an age-dependent epileptic syndrome. The latest neuroimaging techniques have enabled us to gain a better understanding of its physiopathology and to identify new aetiological factors responsible for the clinical symptoms. WS can be due to a number of aetiologies, the most notable of which are congenital errors of metabolism. The incidence of cases due to phenylketonuria or hypoglycaemia is currently diminishing, yet, there is a rise in the number of new metabolic diseases that are responsible for the symptoms of WS. These include the carbohydrate-deficient glycoprotein syndromes or biotinidase deficiency. In all cases, and especially so in those that are idiopathic, it is wise to conduct exhaustive aetiological studies, since on some occasions metabolic diseases will be shown to be responsible, and this will then modify the prognosis, therapy and genetic counselling. It is important to have a protocol for both study and therapy available for this syndrome. The therapeutic options available can be implemented after ruling out a neurometabolic disease as being responsible for the syndrome and quickly beginning treatment with vigabatrine, sodium valproate plus pyridoxine, ACTH or hydrocortisone. If there is no response then topiramate can be used. Other therapeutic options, such as the use of zonisamide, a ketogenic diet or even surgical treatment, are also analyzed.