Keywords
acute subdural hematoma - resolution - spontaneous - conservative management - midline
shift
Introduction
Posttraumatic acute subdural hematoma (PTASDH) is a neurosurgical emergency with mortality
as high as 60 to 80%. Most of these patients, undergo urgent neurosurgical intervention
except for those with poor general condition or with irreversible brain damage. The
natural history of the ASDH is not fully understood because of the early surgical
intervention.
Slow and progressive resolution of SDH occurs in patients treated conservatively.
Rapid resolution of acute SDH is rare and many mechanisms have been proposed for it.
We report a rare case of rapid resolution of acute SDH in a 2-year-old girl with an
associated fracture overlying the SDH.
Case Report
A 2-year-old girl suffered with a blunt head injury due to fall from 14 ft height
and presented with loss of consciousness and vomiting at the emergency department
of a nearby hospital. She was comatose with a score of 9/13 on the Glasgow coma scale
(pediatric) and had left hemiparesis with normal size reacting pupils. Skull X-ray
and computed tomography (CT) scan (2 hour postinjury) demonstrated a right frontal
bone fracture with right frontotemporoparietal acute subdural hematoma and midline
shift of about 1 cm ([Figs. 1] and [2]). Patient was given a loading dose of fosphenytoin and was transferred to our hospital
for further management within next 6 hours. When she was admitted to our emergency
department she was comatose with Glasgow coma scale of E3M5V2. A large subgaleal hematoma
was found over the scalp at the right temporoparietal region. No motor deficits or
pupillary abnormalities were noted. Because the scan was done at other hospital, it
was repeated as per our protocols. Repeat CT scan at 9 hours of injury on the same
day showed that the acute subdural hematoma seen on previous CT scan had resolved
significantly with reduction of the mass effect ([Fig. 3]). It was decided, therefore, to manage the patient conservatively under close observation
in the neurointensive care unit. Repeat CT scans obtained after 12 hours again revealed
the same findings. Of importance was presence of overlying right frontal fracture,
with subgaleal hematoma in both repeat scans. The patient was managed conservatively
and later discharged in satisfactory condition. Repeat scan done just before discharge
showed same findings with appearance of thin subdural hygroma ([Fig. 4]).
Fig. 1 CT brain plain at admission, 2 hours after trauma. CT, computed tomography.
Fig. 2 CT brain plain (bone window) showing the fracture. CT, computed tomography.
Fig. 3 CT brain plain done 9 hours later showing resolution of acute SDH. CT, computed tomography;
SDH, subdural hematoma.
Fig. 4 CT brain 12 hours after second scan showing complete disappearance of SDH. CT, computed
tomography; SDH, subdural hemataoma.
Discussion
An acute PTASDH is defined as a collection of fresh blood under the dura. It is a
common occurrence in severely head-injured patients (10—20% of major head trauma cases)
and is a significant cause of morbidity and mortality.[1] Simple SDHs are hematomas where there is no injury to the brain parenchyma. Successful,
early evacuation of these lesions generally results in rapid recovery, and these patients
have the highest likelihood of a good outcome. On the other hand, complicated SDHs
are associated with surface lacerations, intracerebral hematomas, and parenchymal
contusions.[1] An ASDH with significant midline shift and deteriorated Glasgow coma scale is a
neurosurgical emergency. Spontaneous resolution of ASDH is rare and there are few
case reports in literature. Wen et al reviewed the literature and identified 19 cases
of spontaneous rapid resolution of ASDH. Based on their review, most patients who
developed rapid resolution shared five characteristics[1]
[2]
[3]:
-
Transitory coma lasting no longer than 12 hours,
-
Exclusion of cerebral contusion,
-
Band of low density between the skull and the hematoma on (CT) imaging,
-
Thin width which is widely distributed, and
-
Glasgow Coma Scale >8 on admission.
The mechanism of the PTASDH resolution has been attributed to intracranial redistribution
of the hematoma rather than disappearance in the subdural space. Also, washing out
of the hematoma by cerebrospinal fluid through the torn arachnoid membrane has been
proposed by Nagao et al.[2] A similar phenomenon has also been reported by Matsuyama et al and was believed
to be due to cerebrospinal fluid dilution in the subdural space.[2]
Aoki emphasized the potential for communication between intracranial and epicranial
hematoma through a fracture.[2] Cerebral atrophy may facilitate accommodation and redistribution of ASDH. Liu et
al discussed these hypotheses and also proposed what they call the “Piston theory.”[2] They propose that fluctuation of intraparenchymal cerebral pressure related to agitation
or vomiting acts as a piston to redistribute the ASDH.[2]
In our report, this patient had a linear right frontal bone fracture with PTASDH.
The linear fracture might have facilitated the redistribution of the ASDH and improvement
of the brain shift. This process may be explained by the prolapse of dura mater in
to the fracture sites by the force of the SDH. This phenomenon in turn could have
caused tearing of the arachnoid, and washing out of the hematoma by cerebrospinal
fluid. Another possibility is that diploic veins at the fracture sites might have
drained the subdural space with anatomical connections between the diploae and dural
sinuses.[2]
Conclusion
It is well noted that a large ASDH and a deteriorated neurological examination should
lead to emergent craniotomy. Spontaneous resolution of ASDH is a rare phenomenon with
only a few reported cases in the literature, such as the one illustrated here. Predicting
which patient may have a spontaneous rapid resolution of ASDH, thus preventing emergent
surgical evacuation, can be challenging. In our case patient's weakness on one side
had improved, and CT showed resolution of ASDH as a result craniotomy was avoided.
This further highlights the need of periodic neurological assessment in ASDH patients.
