Scientific collaboration between Professor Marco Toscani and Dr. Pasquale Fino, Chair of Plastic, Reconstructive and Aesthetic Surgery, Umberto I Health Center – “Sapienza” University of Rome.
The life cycle of hair and its subsequent growth occur at a speed of 1-1.5 cm per month. Hair is a living element that follows a follicle cycle with an average duration of 2-6 years. In humans, unlike other mammals that are subject to a periodic change, this cyclic evolution is not synchronous (therefore each hair is independent from the others). A physiological loss of hair up to a maximum of 100 per day is considered normal. Hair grows cyclically following three phases: A growth phase called the anagen phase, a regression phase called the catagen phase and a resting phase called the telogen phase.
With regards to the different lengths of the various phases of the hair growth cycle and in normal conditions, hair in the anagen phase represents 80-90% of the total, that in the catagen phase 1% and that in the telogen phase 10-20%.
There are six sub-phases in the anagen phase. The first five sub-phases last for a very short period of time and consist of the proliferative phase, while the sixth phase is the longest, and is characterized by a phase of differentiation. The duration of the anagen phase differs between men and women. It is recognized that for men it usually lasts 2-4 years, while for women 3-6 years.
The catagen phase represents the moment in which the follicle starts to diminish and slowly ceases mitosis. It has a duration of around 7-21 days. It is difficult to find hair in a trichogram during the catagen phase.
The telogen phase is the resting phase of the follicle and lasts about 3 months, during which the follicular sac that contains the hair bulb climbs towards the epidermis. This climb occurs at the cost of the lower segment of the follicle. In this phase, the bulb assumes its typical clubbed aspect due to the retraction of all the follicular sheaths. Once the climb is complete, the bulb is projected externally and upon the first pull (while shampooing or brushing), it leaves the follicular seat, where the anagen cycle for new hair has probably already started.
In humans, the hair cycle of the various follicles of the scalp is more asynchronous compared to that of mammals that undergo a periodic change. Nevertheless, during the course of the year, in humans we can observe two periods in which hair falls out in the telogen phase. This occurs in the spring and more visibly in the fall. This rhythm seems to obey and submit to the various natural cyclic phenomena, such as the length of the day and the change in temperature in the various days of the year.
Scalp pain and irritation (or trichodynia) are pathological conditions that affect both women (in a greater percentage) and men (in a lower percentage). The pain felt on the scalp, spontaneous or caused by treatment, and in particular around the roots of the hair, may be more or less intense, alternating at times between periods of disappearance, associated with burning, tingling or itching.
Brittle hair is hair that appears opaque and without shininess. It is characterized by glaringly visible damage and deterioration of the shaft.
The causes that lead to the problem of brittle hair may be of endogenous and exogenous origin.
Trichotillomania is a type of hair loss due to voluntary pulling by the patient which often ends up breaking the hair shaft. In general, the patient twists the hair around a finger.
The gesture is occasional when going to sleep or concentrating on a task, but may become repetitive or obsessive.
Greasy hair appears dirty, greasy, oily, shiny and often has an unpleasant odor.
Individuals who have greasy hair often also have other areas of the skin (nose, forehead, chin) that are quite greasy (called “seborrheic” skin).
The term Telogen Effluvium was introduced for the first time by Kligman (*) in 1961 to introduce an acute hair loss of benign origin that follows an intense and short period of stress of different types. Subsequently, Rebora (**) introduced the concept of chronic Telogen Effluvium.
Both men and women of any age may have dry hair. This situation is endured not only as an aesthetic problem, but in time may represent a problem concerning hair health. Dry hair often appears weak, fragile and tends to become brittle and to break.
Dry hair often has split ends and other forms of damage to the shaft.
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