Bahri, MD, H.P.

 A 15- month-old male patient brought by his parents with complains of one episode of focal seizure involving right side of body, developmental delay and disproportional increase in size of head (left>right). Birth history was normal: full term, vaginal delivery and unremarkable. His laboratory investigations were within normal limits.

. T2W axial images showed disproportionate enlargement of left cerebral hemisphere with shallow sulci and enlarged gyri as compared to right side. There was enlarged lateral ventricle with colpocephaly with contralateral displacement of posterior falx and occipital lobe (arrow).

. T1W axial images showed disproportionate enlargement of left cerebral hemisphere with shallow sulci and enlarged gyri as compared to right side. There was enlarged lateral ventricle with colpocephaly with contralateral displacement of posterior falx and occipital lobe (arrow).

. FLAIR axial images showed disproportionate enlargement of left cerebral hemisphere with shallow sulci and enlarged gyri as compared to right side. There was enlarged lateral ventricle with colpocephaly with contralateral displacement of posterior falx and occipital lobe.

. Gradient echo (GRE) and diffusion weighted (DWI) axial images showed similar findings as mentioned previously on T2W, T1W and FLAIR images, and no evidence of abnormal signal intensity of calcification or hemorrhage in GRE and abnormal restricted diffusion in DWI.

. T2W sagittal images showed normally developed corpus callosum and brain stem.

MRI of the brain was performed using T2W, T1W, FLAIR sequences in 1.5 Tesla Siemens Magnetom Essenza.

On T2W, T1W and FLAIR weighted images: Disproportionate enlargement of left cerebral hemisphere with shallow sulci and enlarged gyri as compared to right side. There was enlarged lateral ventricle with colpocephaly with contralateral displacement of posterior falx and occipital lobe. However, there was no evidence of abnormal calcification or associated developmental venous anomalies.

: Hemimegalencephaly is a rare congenital disorder of cortical malformation with hamartomatous overgrowth on all or a part of a cerebral hemisphere. This results from either increased proliferation or decreased apoptosis (or both) of developing neurons. The majority (90 percent) of patients is presented with focal and generalized infantile spasms and developmental delay, hemiparesis and hemianopia are usually also evident.

Hemimegalencephaly is divided into three forms:

1. Isolated form
2. Syndromic form: associated with a variety of syndromes typically including hemicorporal hypertrophy of the ipsilateral part of the body. Such associated syndromes include:

• Epidermal nevus syndrome
• Klippel-Trenaunay syndrome
• McCune-Albright syndrome
• Proteus syndrome
• Unilateral hypomelanosis of Ito
• Neurofibromatosis type 1 (NF1): rare
• Tuberous sclerosis: rare

3. Total hemimegalencephaly: hemihypertrophy also involves the brainstem and cerebellum
All modalities able to image the brain (ultrasound, CT and MRI) will be able to more or less identify the key features, although MRI will give the best imaging. Typical MRI features of the affected hemisphere include:

1. Increased lateral ventricle size, sometimes may be small
2. Shallow sulci enlarged gyri
3. Enlarged/thickened calvaria 4. Contralateral displacement of the posterior falx
5. White matter calcification
6. Associated with developmental venous anomalies (DVAs)
7. The cortex of the involved hemisphere may be normal, but often demonstrates polymicrogyria/ lissencephaly/agyria /pachygyria and grey matter heterotopia

Differential diagnoses include:
• Enlarged hemisphere
• Gliomatosis cerebri
• Small hemisphere, making the normal hemisphere appear large
• Rasmussen encephalitis
• Dyke-Davidoff-Masson syndrome
• Sturge-Weber syndrome
• Other neuronal migration anomalies without overgrowth
• Polymicrogyria/ lissencephaly/agyria/pachygyria


1. Broumandi DD, Hayward UM, Benzian JM, et al. Best cases from the AFIP. 

 2004;24:843–848.
2. Abdel Razek AA, Kandell AY, Elsorogy LG. Disorders of cortical formation: MR imaging features. 

 2009;30:4–11.
3. Shrovan SD, Andermann F, Guerrini R, eds. The Causes of Epilepsy, Common and Uncommon Causes in Adults and Children. Cambridge: Cambridge University Press. 2011.

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Case History: 15-month-old with focal seizure, developmental delay, disproportionate increase in size of head.

Hemimegencephaly

 A 65 year old patient presented with complaint of sudden onset of left sided hemiparesis. He also had complaints of a headache for the past five months. He has a known case of diabetes mellitus and IHD and has had regular treatment. Review of family history was unremarkable. On examination, there was severe loss of motor function on the left side of his body. The patient was then subjected to radiographic investigations.

. Non contrast CT brain shows a large well-defined broad dural based extra axial solid (arrow) cystic lesion in right parietal region causing buckling of underlying cortex and white matter oedema.

. Post-contrast CT brain shows a large well-defined broad dural based extra axial solid cystic lesion in right parietal region causing buckling of underlying cortex and white matter oedema with intense homogenous enhancement of solid portion of the lesion (arrow) and multiple intratumoral vascular channels (small arrow).

. Non-contrast MRI brain shows a large well-defined broad dural based extra axial solid cystic lesion in right parietal region causing buckling of underlying cortex (arrow) and white matter oedema with midline shift of 6 mm towards left side. The lesion appears hyperintense on T2WI with internal dural based solid portion and septations and hypointense on T1WI.

. Post-contrast MRI coronal T1 fat sat images intense homogenous enhancement of broad dural based solid portion of the lesion (arrow) and multiple intratumoral vascular channels (small arrow) and internal enhancing septae.

Non-contrast brain CT revealed a large well-defined broad dural based extra axial solid cystic lesion in right parietal region causing buckling of underlying cortex (Figure 1). On post-contrast study, solid portion of the lesion shows intense homogenous enhancement and multiple intratumoral vascular channels (Figure 2). Further brain MRI showed large extra axial broad dural based solid cystic mass in right parietal causing buckling of underlying cortex and white matter edema with midline shift of 6 mm towards left side (Figure 3).On post-contrast MRI, similar enhancement of the solid part was seen as on the CT and multiple intratumoral vessels and enhancing septae were seen (Figure 4).

 Cystic meningioma is applied to both meningiomas with intratumoral degenerative cyst formation as well as those with peritumoral arachnoid cysts or reactive intraparenchymal cysts. Patients present clinically in the same way as patients with non-cystic meningiomas, with symptoms related to increased intracranial pressure (ICP), focal neurology or seizures.

 divided cystic meningiomas into four subtypes according to the location of the cyst with respect to the brain and meningioma:
Type 1: Intratumoral cyst(s), located centrally within the meningioma
Type 2: Intratumoral cyst(s), located peripherally within the meningioma but still surrounded by tumor
Type 3: Cyst(s) located within the adjacent brain
Type 4: Cyst(s) located between the meningioma and brain (arachnoid cyst)

The tumor itself has imaging features identical to non-cystic meningiomas. The cysts are of variable size and can be entirely surrounded by tumor (types 1 or 2) or clearly between tumor and brain (type 4) or within the adjacent brain (type 3). On imaging it is sometimes difficult to distinguish between these types.

The differential is dependent on the location of the tumor. For tumors around the base of skull, cystic schwannoma (eg, acoustic schwannoma, trigeminal schwannoma) are the main differential, as they share the bright contrast enhancement, and are commonly cystic when large.


1. Buetow MP, Buetow PC, Smirniotopoulos JG. Typical, atypical, and misleading features in meningioma. RadioGraphics 1991;11:1087-1106.
2. Drevelegas A. Imaging of brain tumors with histological correlations. Springer Verlag. 2010.
3. Nauta HJ, Tucker WS, Horsey WJ, et al. Xanthochromic cysts associated with meningioma. J Neurol Neurosurg Psychiatr 1979;42:529-535.

Case History: A 65-year-old patient presented with complaint of sudden onset of left sided hemiparesis.

Bahri, MD, H.P.

Articles

Hemimegencephaly

Cystic Meningioma