Course of Sudden Hair Loss Telogen Effluvium
Acute telogen effluvium has an abrupt onset. The active shedding lasts 1 to 4 months and can lead to thinning of the hair over the entire scalp. The bitemporal areas may be most obviously thinned. Once the daily shedding returns to normal, it may take several months for the scalp hair to regain its normal density. The patient’s hair goes back to normal within 1 year of onset of TE in 95% of people. A specific trigger can be found in approximately 75% of patients with acute TE.
Chronic TE is defined as increased shedding lasting at least 6 months, but usually greater than one year. Chronic TE can last for many years with fluctuating severity. Its onset may be abrupt or gradual. A definite trigger is often not identified in patients with chronic TE. Chronic TE usually affects middle-aged women, many of whom give a history of extremely thick hair prior to the onset of their problem.
Women with chronic TE may have normal-appearing hair (albeit thinner than the patient’s normal hair) or may show shorter frontal hairs or bitemporal thinning. Women with chronic TE often state that they have lost half or one third of their hair. A woman with chronic TE may complain that she is unable to grow her hair as long as she could in the past. Unlike in FPHL, the occipital and crown part widths are approximately the same in patients with both acute and chronic TE.