Amenorrhea is the absence of a menstrual period in a woman of reproductive age. Physiological states of amenorrhoea are seen, most commonly, during pregnancy and lactation (breastfeeding). Outside the reproductive years, there is absence of menses during childhood and after menopause.Amenorrhoea is a symptom with many potential causes. Primary amenorrhea is defined as an absence of secondary sexual characteristics by age 13 with no menarche or normal secondary sexual characteristics but no menarche by 15 years of age. It may be caused by developmental problems, such as the congenital absence of the uterus, failure of the ovary to receive or maintain egg cells, or delay in pubertal development. Secondary amenorrhoea, ceasing of menstrual cycles after menarche, is defined as the absence of menses for three months in a woman with previously normal menstruation, or six months for women with a history of oligomenorrhoea. It is often caused by hormonal disturbances from the hypothalamus and the pituitary gland, premature menopause, intrauterine scar formation, or eating disorders. Pathophysiology
Although amenorrhea has multiple potential causes, ultimately, it is the result of hormonal imbalance or an anatomical abnormality.Physiologically, menstruation is controlled by the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus. GnRH acts on the pituitary to stimulate the release of follicle stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH then act on the ovaries to stimulate the production of estrogen and progesterone which, respectively, control the proliferative and secretary phases of the menstrual cycle.
The observable clinical manifestations may consist of rapid, hyperkinetic movements as well as tonic/dystonic posturing of the limbs. Other potential manifestations include brief arousals from sleep or wandering ambulatory behavior. Non-motor manifestations (such as sensory or emotional phenomenon) are common and retained awareness during seizures may occur. Seizures usually occur during non-REM sleep. The frequency of seizures can be very high and as many as dozens may occur every night which results in poor sleep quality. In addition, many patients with SHE suffer from cognitive impairment and have behavioral/psychological problems. There are many risks associated with nocturnal seizures including concussion, suffocation and sudden unexpected death (SUDEP). Cause
Approximately 86% of SHE cases are sporadic, 14% of patients have a family history of epilepsy and 5% are inherited in an autosomal dominant manner (i.e. autosomal dominant sleep-related hypermotor epilepsy). Both genetic, structural and multifactorial etiologies can occur. In structural cases, the most common pathology is focal cortical dysplasia.The first described mutation in SHE was found in genes coding for the neuronal nicotinic acetylcholine receptor. Since then multiple other genes have been identified including KCNT1, DEPDC5, NPRL2, NPRL3, PRIMA1, CABP4, CRH and others. In some cases, structural and genetic etiologies can coexist such as with mutations in DEPDC5. Diagnosis
The condition may be difficult to diagnose and misdiagnosis is common. The subject may be unaware they have a seizure disorder. To others, the involuntary movements made during sleep may appear no different from those typical of normal sleep.