Keywords
brainstem - hemorrhage - chronic - subdural
Chronic subdural hematoma is a common neurosurgical condition among elderly.[1] Treatment includes evacuation of hematoma by burr hole drainage.[2] Postoperative complications are usually rare and give gratifying postoperative results.
Although rare, unexpected complications may occur. Spontaneous brainstem hemorrhage
following evacuation of chronic subdural hematoma is extremely rare.[3] Literature review showed only five cases of brainstem hemorrhage following chronic
subdural hematoma evacuation of chronic subdural hematoma.
Pathogenesis of brainstem hemorrhage and other remote site hematoma following evacuation
of chronic subdural hematoma is not clear.[4]
[5] Rapid evacuation of hematoma increases the cerebral blood flow due to defective
autoregulation.[4]
[6] This along with massive brain shift and transtentorial herniation due to raised
intracranial pressure[7]
[8] damages fragile atherosclerotic intracerebral vessels[9] leading to remote hemorrhage.[10] Altered coagulation, massive air reflux through burr hole, and labile hypertension
are the other initiating risk factors.
Here we report an extremely rare case of dorsal midbrain hemorrhage and symptomatic
progression of contra lateral hematoma following evacuation of chronic subdural hematoma.
Possible mechanism of remote hemorrhage is discussed in detail after reviewing literature.
Case Report
Our patient, a 50-year-old man, with no comorbidities, was admitted to our hospital
with headache following alleged assault 3 weeks back. Preoperative coagulation profile
was normal. Computed tomography (CT) showed isodense subdural hematoma on the right-sided
frontoparietal region with mass effect to the left side ([Fig. 1]).
Fig. 1 Preoperative CT axial view: thick white arrow showing isodense subdural hematoma
on the right frontoparietal area with small high parietal isodense subdural hematoma
on the left side (thin white arrow).
The patient was taken up for burr hole craniectomy on the right side after obtaining
informed written consent. Two burr hole craniectomies were performed on the right
side in supine position under general anesthesia (GA). Dural opening revealed black
motor oil looking chronic subdural hematoma. Hematoma was evacuated. Irrigation was
done till effluents were clear. The patient was extubated and shifted to the intensive
care unit (ICU). He was drowsy following extubation and decerebrated 3 hours later,
and hence was reintubated and ventilated. Emergency CT scan was taken, which showed
contralateral frontoparietal acute on chronic subdural hematoma with mass effect to
the right side ([Fig. 2A]).There was associated dorsal midbrain hemorrhage with intraventricular extension
([Fig. 2B]). The patient was taken up for emergency burr hole craniectomy for evacuating the
left-sided subdural hematoma ([Fig. 3]). Two burr hole craniectomies were done. Dural opening revealed black motor oil
looking chronic subdural hematoma with fresh clots. Irrigation was done till effluents
are clear.
Fig. 2 (A) Postoperative CT scan showing progression of contralateral thin high parietal subdural
hematoma (white arrow). Black arrow showing drain. (B) Dorsal pons midbrain hemorrhage extending into the ventricular system with minimal
hydrocephalus (thick white arrow).
Fig. 3 Postoperative CT scan after evacuation of contralateral subdural hematoma.
Postoperatively, the patient was electively ventilated for 24 hours. He was weaned
off the ventilator to synchronized intermittent mandatory ventilation (SIMV) the next
day. The patient was localizing to pain with no asymmetry of limbs with the eye opening
on calling and making inappropriate words. There were vertical gaze palsy and truncal
ataxia. Next day, he started obeying commands with spontaneous eye opening and hence
extubated. After 6 weeks postoperative follow-up, he was able to sit with support
and communicate with minimal dysarthria. Six weeks postoperative follow-up showed
near-complete resolution of brainstem hemorrhage with no significant hydrocephalus
([Fig. 4]).
Fig. 4 Postoperative CT scan 2 weeks later showing resolving dorsal midbrain hemorrhage.
Discussion
Chronic subdural hematoma is a common neurosurgical condition among elderly.[1] Burr hole craniectomy is the safest and most effective treatment of chronic subdural
hematoma.[2] Postoperative complications such as residual hematoma, rebleeding, cerebral edema,
infection, seizures, and, rarely, remote intracerebral hemorrhage can occur.
Spontaneous intracranial hematoma associated with evacuation of chronic subdural hematoma
is uncommon and often associated with significant mortality and morbidity. Spontaneous
intracranial hemorrhage can occur on contralateral side and rarely infratentorial
sites such as cerebellum,[11] and intra-axial brainstem can get involved.[8]
Literature review showed only five cases of brainstem hemorrhage. Two cases were detected
following autopsy.[12] One patient succumbed and the fourth gradually improved[8] whereas the fifth died. Here we report an extremely rare case of dorsal midbrain
hemorrhage following evacuation of chronic subdural hematoma, who gradually improved
with conservative management.
Incidence of spontaneous intracerebral hematoma following evacuation of chronic subdural
hematoma is as low as 1 to 5%.[3]
[4]
[5] Pathophysiology of postoperative remote site hematoma following evacuation of chronic
subdural hematoma is not clear.[4]
[5] Rapid evacuation of hematoma increases the cerebral blood flow because of defective
autoregulation.[6] This along with massive brain shift and transtentorial herniation due to raised
intracranial pressure[7] damages fragile atherosclerotic intracranial vessels[9] producing remote site hematoma. Altered coagulation, massive air reflux through
burr hole, labile hypertension, and loss of carbon dioxide reactivity in ischemic
brain may be other initiating risk factors.[4]
[5]
[8]
[10]
Pathophysiology of brainstem hemorrhage following evacuation of chronic subdural hematoma
is difficult to study as it often causes immediate death. A previous animal study
suggested that brainstem hemorrhage was likely due to disruption of damaged atherosclerotic
fragile vessels following raised intracranial pressure.[8] In our case, blood vessels near the brainstem might be stretched and distorted due
to raised intracranial pressure that led to early vascular disruption. Physiologic
aging of cerebral vasculature is associated with poor tolerance of sudden variation
in cerebral blood flow due to defective autoregulation.[4]
[8] Thus the mechanism of brainstem hemorrhage in our patient who was elderly might
be due to mechanical disruption of small fragile intracranial blood vessels. We had
not ruled out secondary pathology such as arteriovenous malformation (AVM), cavernous
malformation, and neoplasm, considering the urgent nature of the condition. Dorsal
midbrain is an extremely rare site for remote hemorrhage following evacuation of chronic
subdural haematoma.[4]
[5]
[8]
The main surgical strategy to avoid the occurrence of remote hemorrhage following
evacuation of chronic subdural hematoma is to do a gradual decompression avoiding
rapid changes in cerebral blood flow. This can be accomplished by applying cotton
strips near the burr hole immediately after opening the outer membrane.[5]
[8] Copious irrigation during the procedure can prevent the sudden brain shift also.[5]
[8]
[10] Continuous closed-system drainage has also been proposed, as this allows the brain
to reexpand slowly to obliterate subdural space.[5]
[8] Head rotation should be minimized as flexion and hyperextension can obstruct the
cerebral venous flow, thus increasing the chance for remote hemorrhage.[4]
[8]
Conclusion
Although evacuation of subdural hematoma gives gratifying results, it is not free
from complications. This case report gives us an insight into the possible mechanism
of remote intracerebral hemorrhage following evacuation of chronic subdural hematoma.
The importance of careful slow decompression of chronic subdural hematoma to avoid
perioperative brain shift is stressed. The need for good postoperative monitoring
to detect early complications is also emphasized.
