subdural hygroma is a subdural body of cerebrospinal fluid ( csf ) collection , without blood .
they can be caused by leakage of csf following minor trauma in the setting of cerebral atrophy , following meningitis in children or more commonly after ventricular shunting .
however , some of them can be large and cause compression and secondary neurological symptoms .
hence , it is important to detect the secondary effects of subdural hygroma on adjacent normal brain parenchyma early and intervene before it causes permanent damage .
we here present the case of a child with post meningitis subdural hygroma and highlight the role tc - ehylene cysteine dimer ( tc - ecd ) hybrid spect / computed tomography ( ct ) can play in such a scenario .
the child had a history of bacterial meningitis 2 year back for which he was treated and declared cured .
magnetic resonance imaging ( mri ) findings revealed bilateral frontal subdural csf collections , suggestive of hygroma , more marked on the left side [ figure 1 ] .
similar collection was also noted in relation to the right cerebellum [ figure 1c and f ] . as subdural hygroma
are known to resolve spontaneously and there was no associated hydrocephalus , the clinician decided for a conservative medical management . because of the parents concern the child was referred to department of nuclear medicine for evaluation of cerebral perfusion .
the child was injected 185 mbq ( 5 mci ) of tc - ecd intravenously and rested in a quiet room .
the spect / ct images confirmed the subdural hygroma [ figure 2a  c ] .
in addition , it also revealed hypoperfusion in bilateral frontal , parietal and temporal cortices [ figure 2d  i ] .
the occipital cortex and cerebellum showed preserved perfusion while the basal ganglia showed relative hyperperfusion .
based on the combination of spect / ct findings and clinical signs , the patient underwent drainage of the subdural hygroma with significant clinical improvement .
trans - axial t1 weighted images ( a , b ) reveal hypointense subdural collection in bilateral fronto - parietal region ( arrows ) , more marked on the left side .
furthermore , noted is the hypointense subdural collection over the right cerebellum ( c , arrow ) .
transaxial t2w image shows hyperintense collections in the same corresponding areas ( d - f , arrows ) .
the ventricles are normal in size and there is no midline shift transaxial tc - ehylene cysteine dimer ( tc - ecd ) hybrid single photon emission tomography / computed tomography ( spect / ct ) images .
the non - contrast transaxial ct images ( a - c ) confirms the subdural hygroma ( arrows ) seen on mri .
transaxial spect ( d - f ) and spect - ct ( g - i ) images demonstrates hypoperfusion involving bilateral frontal , parietal , and temporal cortices ( arrows ) .
contrary to the subdural hygroma , the hypoperfusion is more marked on the right side .
the occipital cortex and the cerebellum show preserved perfusion , while the basal ganglia demonstrate relative hyperperfusion , more marked on the left ( e )
subdural hygroma is subdural accumulation of csf , most commonly seen following head trauma or decompressive craniotomy .
it has also been found to be associated with meningitis , the cause in present patient , and intrathecal chemotherapy .
the factors contributing to the development of subdural hygroma are unknown , but there is probably an underlying disturbance of normal csf absorption or an alteration of the dynamics of csf circulation .
various theories have been proposed to outline the pathogenesis of subdural hygroma including , arachnoid rupture , arachnoid flap , blood - brain - barrier failure , and brain atrophy .
the general consensus is on that of due to arachnoid membrane rupture or arachnoid flap leading to csf accumulation in the subdural space .
subdural hygroma can be seen on ct ; however , the differentiation form subdural hematoma or cerebral atrophy is not always possible .
however , conventional mri is not able to assess the impact of the subdural hygroma on underlying brain parenchyma .
functional imaging in the form of perfusion spect has been shown to be useful to assess these changes secondary to extracerebral fluid collection .
spect with tc - ecd is an established method for assessment of cerebral perfusion , especially for detection of early changes . in the present patient ,
tc - ecd brain perfusion spect showed hypoperfusion in bilateral frontal , parietal , and temporal cortices and provided the imaging correlate for patient symptoms .
in addition , hybrid spect / ct can provide both structural and functional information in a single setting , as in the present case , thereby avoiding the need for a dedicated ct examination .
however , a subset of patients who develop compression symptoms will require surgical intervention to avoid permanent neurological sequelae .
combined structural and functional imaging in the form of tc - ecd brain spect / ct may be especially advantageous for guiding surgical therapy .
these include transfontanel percutaneous aspiration , subdural drains , placement of bur hole(s ) with or without a subdural drain , and shunting .
while shunt placement typically provides good long - term success it has well - known early and late complications .
the minicraniotomy technique may be superior to the burr - hole method , especially in children and was employed in the present case .
the present report highlights the potential role of tc - ecd brain perfusion spect / ct in a case of post meningitis subdural hygroma .
integration of tc - ecd brain perfusion spect / ct in management of such patients can help in decision making with respect to conservative versus surgical management .
 subdural hygroma is the collection of cerebrospinal fluid in the subdural space . 
 most often these resolve spontaneously . 
 however , in cases with neurological complications surgical drainage may be needed . 
 we here , present the case of an 8-year - old boy with post meningitis subdural hygroma . 
 99mtc - ehylene cysteine dimer ( 99mtc - ecd ) hybrid single photon emission tomography / computed tomography ( spect / ct ) carried out in this patient , demonstrated the subdural hygroma as well as the associated cerebral hypoperfusion . 
 if 99mtc - ecd spect / ct is integrated into management of these patients , it can help in decision making with respect to conservative versus surgical management . 
INTRODUCTION
CASE REPORT
DISCUSSION