Hemihypertrophy

HEMIHYPERTROPHY (from the Greek hemi- half and hypertrophy), hypertrophy extending to one half of an organ, one half of the face, the body, or a part of the body. This rare phenomenon depends on a disturbance of the functions of the autonomic centers or pathways on one side. Hemihypertrophy can extend to all tissues, both soft—skin, subcutaneous tissue, muscles—and dense—bones, teeth. Various pathological processes can be the cause of its development; it is sometimes encountered in syringomyelia and can also develop after certain infectious diseases. Hemihypertrophy is sometimes congenital. The pathological anatomy and pathogenesis of this phenomenon have not yet been sufficiently clarified. Hemihypertrophy of the face is characterized by the excessive development of one half of the face; it is both congenital and acquired, but there exists a transitional form between these, where at birth only the hypertrophy of a separate part of the face is noted, while subsequently (see Figure 1) the process extends to the entire half of the face (Stier). In some cases, hemihypertrophy is limited to the skin and subcutaneous tissue, while in others it extends to the bones, which is confirmed by radiographs. In some cases, the muscles also undergo hypertrophy (Cassirer). Hemihypertrophy usually develops unevenly. Of the bones, the zygomatic arch and the upper jaw are most severely affected, and of the soft parts, the cheek and upper lip. Unlike hemiatrophy (see Hemiatrophy), which affects the left side predominantly, hemihypertrophy is observed on the right side in the majority of cases (according to Stier, out of 75 right-sided cases of hemihypertrophy, 45 were left-sided).

Figure 1. Hypertrophy of the right half of the face.

On the affected side, premature hair growth or hypertrichosis is often noted. In the majority of cases, deviations in the development of teeth are noted; sometimes teeth erupt earlier on the affected side, and in other cases, their size is larger or their number is even increased. The fact that, like hemiatrophy, hemihypertrophy can be complicated by scleroderma deserves special attention. In the majority of cases, hemihypertrophy develops without a visible cause, but cases have been described where its development was preceded by injuries or other local pathological processes, and sometimes the disease was preceded by infectious diseases. Levin was the first to express the opinion that hemihypertrophy is a trophoneurosis; this view is also supported by Cassirer. Hoffmann, on the basis of cases of hemihypertrophy combined with organic diseases (syringomyelia, acromegaly, etc.), expresses the assumption of damage to trophic centers. Stier also speaks in favor of a central localization, while believing that it can be not only subcortical but also cortical (a point of view that is hardly correct). In the opinion of Müller, hemihypertrophy, like hemiatrophy, depends on a disease of the sympathetic nerve, its trophic fibers, and can be of both peripheral and central origin. Hemihypertrophy is sometimes not limited to the face and, like hemiatrophy, affects the neck, shoulder girdle, upper limb (see Figure 2), or the entire half of the body (total hemihypertrophy). General hemihypertrophy is more often congenital. Lenstrup published 8 cases observed over a short time in Copenhagen. Reed described congenital hemihypertrophy in a brother and sister. Cases of total hemihypertrophy speak in favor of localization in the brain: the trophic centers of the subcortical ganglia are affected. Similar to the crossed form of hemiatrophy (see Hemiatrophy, hemiatrophy cruciata), isolated, extremely rare cases of crossed hemihypertrophy have been described.