Congenital hemiatrophy of the brain.

Hemiatrophy of the brain may occur in adults and in old age as a result of degenerative or vascular disorders, but the name is more commonly applied to the congenital or the infantile variety of the condition. It was proposed by Alpers and Dear (1939) that the two varieties be designated secondary and primary respectively. The condition is, however, always secondary in the sense that it is due to some cause which is frequently ascertainable. It is therefore better to speak of the adult and of the congenital (or infantile) varieties of hemiatrophy. The object of this report is to present a case and to discuss some pathological aspects of such congenital hemiatrophy. The reduction in size of the brain in such cases is caused by loss of nerve tissue and its replacement by glial scars. The replacement is, in some cases, inadequate, and foci of acellular necrosis as well as cysts are frequently found. The larger cysts are usually filled with clear fluid, while the smaller ones may contain debris with fat and blood pigment phagocytes. Concomitant findings may include granular atrophy of gyri, ulegyria, status spongiosus, status marmoratus, thickening of blood vessels, mesenchymal proliferation, meningeal fibrosis, and hydrocephalus. The extent and severity of the lesions are, by definition, more marked on one side, but the condition is seldom, if ever, strictly unilateral, some degree of scarring being also present in the second hemisphere. The basal ganglia may likewise be reduced in size on the affected side and this is accompanied by a crossed cerebellar atrophy. This association enabled Mott and Tredgold (1900) to deduce that such cerebellar atrophy depends on the involvement of the basal ganglia. Glial scars may also be found in the brain stem. It was suggested by Schob (1930) that cerebral hemiatrophy comprises two distinct conditions: a variety of lobar scarring or ulegyria in which the lesions extend beyond a single lobe to affect a whole hemisphere and, secondly, progressive sclerosing hemiatrophy. Parenchymal loss is more uniform and usually less severe in the second condition, and the lesions are found chiefly in one of the cortical laminae, especially the third. Areas of focal destruction are uncommon. Blood pigment and fat-laden phagocytes are less numerous and are scattered more diffusely through the cortex, while the gliosis affects chiefly the digital white matter and is restricted in the cortex to its margin and the third lamina. Clinically, the condition is characterized by a more progressive mental deterioration and epilepsy. The existence of this distinct variety of hemiatrophy has been endorsed by Toppich (1935) and by Josephy (1945). One of the earliest cases of cerebral hemiatrophy was reported by Charcot and Turner (1852). They found it in a mentally defective epileptic woman aged 20, and quoted Cazanviech and Calmiel as originators of the term 'atrophie ou agenesie cerebrale' which they themselves used to designate this condition. By 1861, when the Dutch anatomist Schroeder van der Kolk contributed a scholarly description of a case, which, in the manner of his time, was both long and detailed, there were already 29 similar cases on record. Later contributions included those of Howden (1875), Major (1879), Mott and Tredgold (1900). Kdppen (1905), Spielmeyer (1906), Boyd (1912), Bielschowsky (1917), Stroh (1925), Brushfield and Wyatt (1927), Pekelsky (1932), Hassin (1935), Casamajor and Laidlow (1939), Alpers and Dear (1939), Liber (1940), Moore (1943), and Josephy (1945). Most of the patients described in the literature have been mental defectives, others were cases of Little's disease, of hemiplegia, with or without extrapyramidal signs, and of epilepsy. Many cases have been diagnosed correctly during life and such diagnosis usually rested on the history, the neurological and psychiatric signs, and the radiological findings. The latter have been the subject of