this study reports a rare patient of a rapid spontaneously resolving acute subdural hematoma . in addition , an analysis of potential clues for the phenomenon is presented with a review of the literature . a 1-year - and-2-month - old boy fell from a height of approximately 2 m. the patient was in a superficial coma with a glasgow coma scale of 8 when he was transferred to the authors hospital . computed tomography revealed the presence of an acute subdural hematoma with a midline shift beyond 1  cm . repeat imaging after 15  hours showed the evident resolution of the hematoma and midline reversion . progressive magnetic resonance imaging demonstrated the complete resolution of the hematoma , without redistribution to a remote site . even though this phenomenon has a low incidence , the probability of a rapid spontaneously resolving acute subdural hematoma should be considered when patients present with the following characteristics : children or elderly individuals suffering from mild to moderate head trauma ; stable or rapidly recovered consciousness ; and simple acute subdural hematoma with a moderate thickness and a particularly low - density band in computed tomography scans . a 1-year - and-2-month - old boy fell from a height of approximately 2 m and lost consciousness after he experienced head trauma . the patient was sent to a local hospital immediately . during the interval emergent computed tomography ( ct ) , the patient vomited several times . 1a ) revealed a right frontotemporal asdh that was approximately 9  mm in size with a subarachnoid hemorrhage in the longitudinal fissure and midline shift beyond 10  mm . he was in a superficial coma with the same gcs score that was documented in previous medical records . both of the patient 's pupils were equal in size 2  mm but exhibited a blunted response to light . 1b ) showed a decrease in hematoma density and diffuse cerebral edema with obviously squeezed ventricles ; the midline was still deviated compared with the first ct scan . given his consciousness and imaging findings , intracranial pressure monitoring was preferred . even though the laboratory features were not surgical contraindications , the boy 's guardians refused the placement of an intracranial pressure probe or a craniotomy . general monitoring aimed to maintain sao2 at > 95% , mean systolic blood pressure at > 90 mm hg , temperature at < 37c , and paco2 at 35 to 40 mm hg . owing to the lack of an accurate intracranial pressure assessment , mannitol was administered empirically at 0.5  g / kg every 6  hours . the third ct scan ( fig . 1c ) revealed evident resolution of the hematoma and midline shift improvement , with only a subarachnoid hemorrhage present in the posterior longitudinal fissure 24  hours after the trauma . after he had received 2 days of conservative management , the boy regained consciousness . c ) showed that the asdh was almost completely resolved on the fourth day after admission , without redistribution to the upper cervical spinal cord . ( a ) initial ct scan revealed right frontotemporal acute subdural hematoma ( arrow to show ) , with sah in anterior longitudinal fissure and midline shift exceeding 10  mm . ( b ) a second ct scan showed the decrease of hematoma ( arrow to show ) with obvious diffusion cerebral edema . ( c ) a third ct scan was taken after 24  hours of the injury revealed an evident resolution of hematoma ( arrow to show ) and midline revert with only sah left in posterior longitudinal fissure . ct , computed tomography ; sah , subarachnoid hemorrhage . magnetic resonance imaging on the fourth day of conservative management . transverse ( a ) , sagittal ( b ) , and coronal ( c ) planes were performed which revealed acute subdural hematoma complete resolution without redistribution to upper cervical spinal cord . the following 2 possible explanations were proposed : the asdh was diluted and washed out by cerebrospinal fluid ( csf ) after the tearing of the arachnoid membrane and the hematoma was redistributed to the subdural space . wong et al measured the hounsfield units of the subarachnoid space , which was close to normal , and confirmed the redistribution of a hematoma to the subdural space then to the subarachnoid space . the theory was based on the flow of liquefied blood , which was thought to be driven by the change in intraparenchymal pressure . in those patients without available definitive evidence of blood redistribution , csf flushing seems more likely . based on table 1 , rapid resolution occurred more frequently in children , less frequently in elders , and least often in middle - age individuals . in children and elders , asdh is often caused by mild or moderate injuries , such as falling or slipping . in elderly individuals , brain atrophy and a wide cavum of the subarachnoid space can cause an arachnoid membrane slit under external force . for middle - age individuals , well - developed brain tissue and narrow compensatory space results in an arachnoid membrane that is comparatively difficult to tear with a mild injury . wen et al proposed that gcs was higher than 8 in patients who exhibited this phenomenon . however , in table 1 , 7 of 18 patients exhibited a gcs score of less than 8 , and the minimum was 5 . in the process of the clinical evaluation , the dynamic change in consciousness is a more heavily weighted factor to consider than the initial gcs score . according to a review of all patients ( table 1 ) , most of those patients regained consciousness quickly . although some of those patients did not regain consciousness quickly , their conditions were stable . in our case , the patient 's consciousness improvement was even slower than the time of resolution according to the ct scan . thus , by comparing the initial gcs score after head trauma , we inferred that a rapid recovery or relative stabilization of consciousness is more persuasive in these patients . the evaluation of images from ct scans that were performed during different phases of our patient clearly demonstrated the rapid transition of hematoma density from a high density to a mixed density . some authors agreed that the potential sign in early ct of a rapid resolution was the presence of a low - density band . in our patient 's second ct scan ( fig . 1b ) , it was observed that remarkable cerebral edema could squeeze , in some way , the diluted hematoma . kuroiwa et al suggested that diffuse cerebral edema was necessary for the spontaneous resolution of a hematoma . we speculate that cerebral edema leads to resolution via both mechanisms , but it may not be the prerequisite for hematoma rapid resolution . indeed , in most patients , the diffuse edema was not even observed ( table 1 ) . we propose that the slice or middle thickness hematoma ( < 1.5  cm ) would be suitable in the consideration of rapid resolution . lee et al reported a patient with a hematoma thickness that was larger than 2.5  cm , yet it finally converted to a chronic subdural hematoma . the presence of simple asdh without contusion appears to be associated with rapid resolution . we suspect that this effect is due to the mass effect of the contusion , which impeded the flow of csf in the limited space . this patient has been reported because of clear evidence of csf dilution and a flush effect that led to resolution of the hematoma , and the finding that a distinctly swollen brain probably accelerated the process . there is no need for the deliberate evaluation of the phenomenon as a coincidence during treatment . we suggest that asdh rapid resolution should be considered when patients present with the following characteristics : children or elders suffering from mild to moderate head trauma ; stable or rapidly recovered consciousness ; and simple asdh with moderate thickness and a particularly low - density band in ct scan images .
introduction : this study reports a rare patient of a rapid spontaneously resolving acute subdural hematoma . in addition , an analysis of potential clues for the phenomenon is presented with a review of the literature.patient presentation : a 1-year - and-2-month - old boy fell from a height of approximately 2 m. the patient was in a superficial coma with a glasgow coma scale of 8 when he was transferred to the authors hospital . 
 computed tomography revealed the presence of an acute subdural hematoma with a midline shift beyond 1  cm . 
 his guardians refused invasive interventions and chose conservative treatment . 
 repeat imaging after 15  hours showed the evident resolution of the hematoma and midline reversion . 
 progressive magnetic resonance imaging demonstrated the complete resolution of the hematoma , without redistribution to a remote site.conclusions:even though this phenomenon has a low incidence , the probability of a rapid spontaneously resolving acute subdural hematoma should be considered when patients present with the following characteristics : children or elderly individuals suffering from mild to moderate head trauma ; stable or rapidly recovered consciousness ; and simple acute subdural hematoma with a moderate thickness and a particularly low - density band in computed tomography scans .