Investigation: When numerous fibers are affected, small white spots are easily seen on the hair with the naked eye and can be confirmed with a hand lens. Transmitted or plane polarized light microscopy shows characteristic focal burst along the fiber or brush breaks where the node has parted. Additional observations should be made of the apparently normal parts of the fiber to rule out any predisposing conditions, such as piliannulati or pilitorti, that may previously have gone unnoticed.
While it is important to exclude any underlying pathology or metabolic changes, it is unlikely that a patient who previously had normal hair will have developed significantly weaker hair. It must be remembered that where trichorrhexis nodes appear toward the tips on longer fibers, that part of the hair was actually formed many months before the patient presented with trichorrexhis nodosa. It is, therefore, unlikely that a fundamental fiber weakness has “grown in.” It is most probable that the trichorrehexis nodes are a result of cosmetic practices. These practices may create only minimal damage to the fiber. However, the combination of insults and insuffi cient care may result in catastrophic fiber damage. In order to understand the severity of a patient’s cosmetic regimen it may be useful to measure the distance from the scalp to the fi rst onset of trichorrhexis nodosa as an indication of how long the best part of the fiber can withstand the current level of trauma. It is probable that a chemical (permanent wave) or thermal (tongs) insult is indicated in the process. The current fashion trend for perfectly straight hair has spawned a number of treatments and straightening irons that claim to be good for the hair. The author has observed an increase in trichorrhexis nodosa among young females who are seemingly “wedded” to their straightening irons.
