Cerebral Hemiatrophy (CHA) or unilateral brain atrophy is the end-stage of various pathologies culminating in atrophy or hypoplasia of a single cerebral hemisphere [9].
Cognitive derangement,
behavioural change,
hemiplegia,
seizures and emotional deficits are possible functional implications [16].
Radiologically,
there is cerebral hemiatrophy with contralateral thickening of calvarium ,
ipsilateral hyperpneumatization of paranasal air sinuses,
elevation of petrous ridge and associated parenchymal changes.
Cerebral hemiatrophy is infrequently encountered in paediatric clinical practice.
However it exists and could be primary or secondary.
The primary (congenital) CHA could be interwoven or aptly called cerebral hemi-hypoplasia or unilateral cerebral hypoplasia as it could actually be de-novo lack of cerebral development.
Here,
the insult occurs in-utero,
with consequent shift of midline structures towards the side of the disease and absence of sulcal prominence.
These features differentiate it from secondary CHA which could originate from cerebrovascular lesion,
inflammatory process or cranial trauma [2,7,14].
Possible aetiologies of cerebral hemiatrophy are as follows:
(A) Congenital
o Idiopathic
o Intrauterine vascular injury
(B) Acquired
o Birth trauma
o Perinatal intracranial haemorrhage
o Rasmussen's encephalitis
o Postictal cerebral hemiatrophy,
Prolonged febirile seizures
o Infections like Herpes Encephalitis,
TORCH syndrome,
HIV
o Vascular/Haematological abnormalities like Dyke Davidson Masson syndrome,
Sturge-Weber syndrome,
Crossed Cerebral Cerebellar Diaschiasis,
Diaschiasis Commisuralis,
Hemiplegia-Hemiatrophy Hemiconvulsion syndrome
o Ischaemia
o Neoplasia like basal ganglial germinoma
o Radiation
o Phakomatosis ( Neurofibromatosis)
o Miscellaneous-Linear Nevus syndrome,
Fishman syndrome,
Silver-Russell syndrome,
Infantile hemiplegia syndrome,
Congenital malformation,
Intrauterine coactation of aorta,
Perinatal anoxia/hypoxia; Mitochondrial encephalopathy,
lactic acidosis,
and stroke-like episodes (MELAS) [1,5,7,14,15].
CT & MRI are the preferred modalities in assessment of the aetiology and lesion extent of cerebral parenchyma in atrophy,
seizures,
hemiparesis/plegia,
and craniofacial asymmetry [3].
Pathologic accompaniment in brainstem and cerebellar hemisphere are further elaborated by MRI [13].
Role of imaging is to throw light on the characteristic radiological findings associated with diverse pathologic conditions causing cerebral hemiatrophy so as to aid etiological stratification,
which is further imperative for choosing therapeutic modalities such as surgical intervention or medical treatment.
Since CT and M.R.I.
imaging features of many of these lesions overlap & are often non-specific,
we will highlight those imaging features that allow one to formulate a reasonable differential diagnosis.