Case No. :	46
Month :	October
Year :	2002
Contributor :	Dr. Joseph Lazar

This is a case of a 23-year lady who had come for a routine antenatal obstetric scan at 32 weeks of gestation. Clinical examination and routine antenatal investigations were normal.

On ultrasonography, an axial section of the fetal head revealed intracranial calcifications confirming to a periventriclur location (Fig 1 & 2).

Fig.1	Fig.2

There was mild hydrocephalus. The ventricle/hemisphere ratio was 0.4. There was also a well-defined, cystic structure posterosuperior to the third ventricle.

Since the most common cause of intracranial calcifications is intrauterine infection and since the calcifications were distributed in a periventricular location, a diagnosis of 'TORCH' infection was made. The cystic structure posterosuperior to the third ventricle was diagnosed as cavum vergae.

The lady delivered two weeks following the scan. A lateral radiograph (Fig. 3) of the neonate's skull revealed foci of calcifications extending along the periventricular regions.

Fig.3

Fig.4	Fig.5

Fig.6	Fig.7

It also revealed calcific foci in both basal ganglia. Meanwhile reports of serum titers came positive for cytomegalovirus and taxoplasmosis confirming the diagnosis.

DISCUSSION:

The TORCH group of infections are the most common cause of intracranial calcifications which can detected in utero. They comprise toxoplasmosis, rubella, cytomegalovirus and herpes. Of these, cytomegalovirus is the most common followed by toxoplasmosis, rubella and herpes.

Cytomegalovirus has a particular affinity for affecting the developing germinal matrix, which is followed by dystrophic calcification. This results in the typical periventricular location of the calcifications. Other radiological abnormalities, which can be seen, are migrational anomalies, hydrocephalus, encephalomalacia, delayed myelination and subependymal cysts and calcifications.

Toxoplasmosis is caused by Toxoplasma gondi which causes calcifications in the cerebral cortex and basal ganglia in contrast to CMV which causes periventricular calcifications. It also causes hydrocephalus as a result of periaqueductal necrosis causing periaqueductal stenosis.

Rubella shows subependymal cysts in the caudate nucleus and the striothalamic regions, echogenic foci in the basal ganglia and cortex representing mineralizing vasculitis and delayed myelination due to oligodendroglia.

Herpes infections presents as focal or diffuse white matter lucencies causing relative hyperdensity of the cerebral cortex. In the long term, it can cause diffuse atrophy and encephalomalacic changes.

Other causes of antenatally detected intracranial calcifications are tuberous sclerosis, Sturge-Weber syndrome, teratomas and venous sinus thrombosis.

Tuberous sclerosis shows calcific foci in the subependymal regions and in the striothalamate groove. Teratomas appear as mixed echogenic masses with foci of calcification within. Sturge weber syndrome presents as curvilinear gyral calcifications seen typically in the posterior parietal and occipital regions.

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