---

Discussion

Dyke-Davidoff-Masson syndrome was described as skull radiographic and pneumatoencephalographic changes in a series of 9patients whose clinical characteristics included hemiparesis, seizures, facial-asymmetry, and mental retardation in 1933 by Dyke-Davidoff and Masson [5].

Clinically it is characterized by seizures, facial asymmetry,contralateral hemiplegia or hemiparesis and mental retardation. However, mental retardation is not always present and seizures may appear months or years after the onset of hemi paresis. The clinical findings may be of variable degree according to the extent of the brain injury [1,6]. Both sexes and any of the hemispheres may be affected but male gender and left hemisphere involvement are more frequent [2]. This condition is usually diagnosed in childhood but rarely diagnosis can be made in teenagers and young adults [2].

The etiology of cerebral hemiatrophy may be classified into twogroups:

Congenital or Primary

Acquired or Secondary

In the congenital type, cerebral damage which usually has avascular origin, occurs during intrauterine life and symptoms appear at birth or shortly thereafter.

In the acquired or secondary type, cerebral insults occur duringthe perinatal period or later. The main etiologic factors involved aretrauma, infection, vascular abnormalities of the cerebral circulation,ischemic and hemorrhagic states, and in premature infants, subependymal germinal matrix and intraventricular haemorrhage [3,4]. In-utero gestational vascular occlusion involving middle cerebralvascular territory or coarctation of mid-aortic arch may decrease carotid arterial flow [1,7].

The involved hemisphere will have prominent sulcal spaces if thevascular insult occurs after birth or after sulcation is complete. On theother hand, if the vascular ischaemia occurs during intrauterine life,when the formation of gyri and sulci is incomplete, no prominentsulci will be present.

There may be variable extent of hypoplasia/atrophy of thecerebral peduncle, thalamus abnormal myelination and contralateral/ipsilateral cerebellar atrophy on the affected side. Encephalomalacia,gliosis, porencephaly, loss of white and gray matter substance, ipsilateral ventricular enlargement and midline shift may also be present in the hemiatrophic brain [3,4].

The brain reaches half of its adult size during the first year of life and reaches three-fourths of that size by the end of third year. As it enlarges, the brain presses outward on the bony tables and ispartly responsible for the gradual enlargement and general shape of the adult head. When the brain fails to grow properly, the other structures tend to direct their growth inward, thus accounting for the enlargement of the frontal sinus, the increased width of the diploic space and the elevations of the greater wing of sphenoid and the petrous ridge on the affected side [8]. These change can occur onlywhen brain damage is sustained before three years of age however, such changes may become evident as soon as nine-months after brain damage was sustained [9]. CT is preferred to conventionalradiography in DDMS as changes on skull plain radiographs may be so subtle and overlooked.

Shen et al., described three patterns of MRI showing cerebralhemiatrophy: MRI pattern I corresponds to diffuse cortical and subcortical atrophy; pattern II corresponds to diffuse cortical atrophycoupled with porencephalic cysts and pattern III corresponds to previous infarction with gliosis in middle cerebral artery territory [10].

Less common than ipsilateral cerebellar atrophy, contralateral or crossed cerebellar atrophy has also been described in the cerebral hemiatrophy syndrome and it is associated with long-standing, extensive and unilateral cerebral lesions with onset during infancy or early childhood [11].

Important differential diagnosis is Sturge Weber Syndrome,Rasmussen Encephalitis, Hemiconvulsion-Hemiplegia-Epilepsy Syndrome (HHE), Silver symdrome and some brain tumour [8,3]].

The treatment for DDMS is symptomatic and includesmanagement of seizures, hemiplegia or hemiparesis. The prognosis for the disease is better for patients who develop hemiparesis beyond the age of two years and also if there is no history of prolonged or recurrent seizures [12]. Children with intractable disabling seizures and hemiplegia are the potential candidates for hemispherectomy with a success rate of 85% in carefully selected cases [13].

In the present case, the classical features of the acquired type of cerebral hemiatrophy were found. The findings of dilated sulci and ventricle in the left hemisphere reflect a late onset of brain insult which was the consequence of premature delivery.

The prognosis in our patient is expected to be good as he had a long seizure free interval after the initial episode and that he was able to carry out his daily activities and functioning.