Question: What is the characteristic feature of the Dyke-Davidoff-Masson syndrome.

Context:
Dyke-Davidoff-Masson syndrome is a rare condition characterized by cerebral hemiatrophy, calvarial thickening, skull and facial asymmetry, contralateral hemiparesis, cognitive impairment and seizures.
Dyke-Davidoff-Masson syndrome refers to atrophy of one cerebral hemisphere (hemiatrophy) due to an insult to the brain in fetal or early childhood period. 
Acquired cerebral hemiatrophy: Dyke-Davidoff-Masson Syndrome - a case report.
CT and MRI scan of the head showed hemiatrophic cerebral parenchyma with prominent sulci and encephalomalacia.
CT of the brain revealed characteristic features diagnostic of infantile type of cerebral hemiatrophy or Dyke-Davidoff-Masson syndrome.
Magnetic resonance imaging (MRI) of brain revealed atrophic of left cerebral hemisphere with mildly ventricular dilatation, prominent paranasal and mastoid air cells, suggestive of Dyke-Davidoff-Masson syndrome (DDMS).
Imaging showed resolution of the infection and features of Dyke-Davidoff-Masson syndrome (cerebral hemiatrophy). 
Dyke-Davidoff-Masson syndrome (DDMS) is a rare epilepsy syndrome that is characterized by cerebral hemiatrophy, homolateral skull hyperplasia, hyperpneumatization of the paranasal sinuses, seizures with or without mental retardation, and contralateral hemiparesis. 
Brain MRI showed prominent atrophy in the left frontal dorsal and lateral regions and mild atrophy of the left superior temporal gyrus and left parietal gyri.
A 15-year-old female presented with seizures, right-sided hemiparesis, hemiatrophy of the right side of the body and mental retardation. 
Described here is the case of a girl with a reticulated capillary malformation on the right side of her face, along with Dyke-Davidoff-Masson syndrome, as evidenced by microphthalmia and severe associated anomalies in the right eye, and right cerebral hemispheric atrophy and cerebral arteries malformations.
The purpose of this study was to retrospectively evaluate the cognitive and electroclinical characteristics of right cerebral hemiatrophy (Dyke-Davidoff-Masson syndrome [DDMS]). 
The CHA of childhood or Dyke-Davidoff-Masson syndrome, is originated by intrauterine or perinatal insults that affect the perfusion of a single cerebral hemisphere, manifesting clinically by variable mental retardation, refractory epilepsy, facial asymmetry, hemiplegia/hemiparesis or abnormal movements of the contralateral extremities and by imaging studies, loss of volume in one cerebral hemisphere and ipsilateral compensatory cranial changes such as skull vault thickening, elevation of the orbital roof and petreous ridge, also hyperpneumatization of the frontal sinus and mastoid cells.
Dyke-Davidoff-Masson syndrome is a disorder involving hemiatrophy or hypoplasia of 1 cerebral hemisphere secondary to an insult in the developing brain. Often this will manifest with seizures, hemiparesis, mental retardation, and facial changes. Associated with this pathology are the radiologically evident changes, such as thickening of the calvarium, hyperpneumatization of the sinuses, and dilation of the ipsilateral lateral ventricle among others.
Dyke-Davidoff-Masson syndrome, or cerebral hemiatrophy, is a pre- or perinatally acquired entity characterized by predominantly neurologic symptoms, such as seizures, facial asymmetry, contralateral hemiplegia, and mental retardation. 
The Dyke-Davidoff-Masson syndrome is characterized by various symptoms related to hemiatrophy of the cerebrum and hypertrophy of the ipsilateral calvarium and paranasal sinuses. Clinical findings include hemiparesis or hemiplegia, seizures and/or mental retardation. 
Asymmetry of cerebral hemispheric growth with atrophy on one side, ipsilateral osseous hypertrophy and hyper-pneumatization of sinuses with contralateral paresis are features of Dyke Davidoff Masson Syndrome (DDMS). 
Dyke Davidoff Masson syndrome (DDMS) is characterized by seizures, facial asymmetry, contralateral hemiplegia and mental retardation. The characteristic radiologic features are cerebral hemiatrophy with homolateral hypertrophy of the skull and sinuses. We report a case of DDMS in an 18-month-old girl who presented with right sided focal seizures, hemiparesis of the same side, and delayed milestones.
Cerebral hemiatrophy (Dyke-Davidoff-Masson syndrome) in childhood: clinicoradiological analysis of 19 cases.
The so-called Dyke-Davidoff-Masson syndrome (DDMS) is a rare disorder of cerebral hemiatrophy. The clinical presentation may consist of facial asymmetry, contralateral atrophy (including the trunk, and the extremities) and hemiparesis, speech difficulties, mental retardation, and epilepsy.
Dyke-Davidoff-Masson syndrome is clinically characterized by hemiparesis, hemiplegia, seizures, mental retardation, and facial asymmetry secondary to congenital or early childhood vascular insult. A 21-year-old man with Dyke-Davidoff-Masson syndrome presented with uncontrolled seizures.
Dyke-Davidoff-Masson syndrome is a condition characterized by seizures, facial asymmetry, contralateral hemiplegia or hemiparesis and mental retardation.
Brain MRI showed unilateral loss of cerebral volume with hypertrophy and hyperpneumatization of the paranasal sinuses and mastoid cells. 
Although radiological findings of cerebral hemiatrophy (Dyke-Davidoff-Masson Syndrome) are well known, there is no systematic study about the gender and the affected side in this syndrome.
The patient was a 19-year-old woman who presented with hemiatrophy and diminished superficial sensation on the left side of her body including her face. She had a past history of tonic-clonic seizures accompanied by left hemiparesis in late childhood. Brain CT demonstrated dilatation of the frontal sinus, calvarial thickening, cerebral hemiatrophy and dilatation of the lateral ventricle on the right side. Brain MRI showed atrophy of the right cerebrum and midbrain and dilatation of the lateral ventricle on T1-weighted images, as well as a high signal intensity area from the parietal to the occipital lobe on T2-weighted images. 
Cerebral hemiatrophy or Dyke-Davidoff-Masson syndrome is a condition characterized by seizures, facial asymmetry, contralateral hemiplegia or hemiparesis, and mental retardation. 
The radiological features are unilateral loss of cerebral volume and associated compensatory bone alterations in the calvarium, like thickening, hyperpneumatization of the paranasal sinuses and mastoid cells and elevation of the petrous ridge. 
We reported a 39-year-old man with Dyke-Davidoff-Masson syndrome presenting with total hemiatrophy. 
This paper presents an 18-year-old mentally retarded patient with cerebral hemiatrophy (Dyke-Davidoff-Masson syndrome) associated with a growing skull fracture in the ipsilateral hemicranium, in whom not only a dural tear but also the ipsilaterally displaced and dilated lateral ventricle due to the original disease apparently contributed to the development of growing skull fracture.
The magnetic resonance (MR) findings of three patients with cerebral hemiatrophy, the so-called Dyke-Davidoff-Masson syndrome, which is characterized by variable degrees of unilateral loss of cerebral volume and compensatory changes of the calvarium are presented.
MRI brain revealed characteristic features diagnostic of congenital type of cerebral hemiatrophy or Dyke-Davidoff-Masson syndrome.
Imaging showed resolution of the infection and features of Dyke-Davidoff-Masson syndrome (cerebral hemiatrophy).
Asymmetry of cerebral hemispheric growth with atrophy on one side, ipsilateral osseous hypertrophy and hyper-pneumatization of sinuses with contralateral paresis are features of Dyke Davidoff Masson Syndrome (DDMS).
CT of the brain revealed characteristic features diagnostic of infantile type of cerebral hemiatrophy or Dyke-Davidoff-Masson syndrome
Dyke-Davidoff-Masson syndrome refers to atrophy of one cerebral hemisphere (hemiatrophy) due to an insult to the brain in fetal or early childhood period
Magnetic resonance imaging (MRI) of brain revealed atrophic of left cerebral hemisphere with mildly ventricular dilatation, prominent paranasal and mastoid air cells, suggestive of Dyke-Davidoff-Masson syndrome (DDMS)
Dyke-Davidoff-Masson syndrome is a relatively rare syndrome with its typical clinical and radiological features including facial asymmetry, hemiplegia, cerebral hemiatrophy, mental retardation with calvarial thickening, hypertrophy of sinuses and elevated petrous ridge on imaging
Dyke Davidoff Masson syndrome (DDMS) refers to atrophy or hypoplasia of one cerebral hemisphere following a prior fetal or childhood insult
The purpose of this study was to retrospectively evaluate the cognitive and electroclinical characteristics of right cerebral hemiatrophy (Dyke-Davidoff-Masson syndrome [DDMS])
We describe a female infant with prenatal diagnosis of unilateral left ventriculomegaly in which early brain MRI and contrast enhanced-MRI angiography, showed cerebral left hemiatrophy associated with reduced caliber of the left middle cerebral artery revealing the characteristic findings of the Dyke-Davidoff-Masson syndrome

Answer: Cerebral hemiatrophy (atrophy of one cerebral hemisphere) is the characteristic feature of the Dyke-Davidoff-Masson syndrome. It develops due to an insult to the brain in fetal or early childhood period. Calvarial thickening, skull and facial asymmetry, contralateral hemiparesis, cognitive impairment and seizures are also characteristic to the Dyke-Davidoff-Masson syndrome.
.
Exact answer: cerebral hemiatrophy