a 22-year - old , stuporous , but previously healthy man , 182 cm in height and 70 kg in weight , was admitted to the emergency room with an accidental injury from a fall .
an emergent brain ct demonstrated acute traumatic subdural hematoma , thus an emergent decompressive craniectomy and hematoma removal was performed under general anesthesia without any remarkable incidences .
after the first operation , the patient had not made favorable progresses , therefore several further operations such as brain abscess drainage , external ventricular drainage catheter insertion , cerebral lobectomy , ventriculoperitoneal shunt were performed during a 4 month period .
the vital signs of the patient scheduled for cranioplasty were a systolic / diastolic blood pressure of 110/70 mmhg , heart rate 104 bpm , respiratory rate via tracheostomy 20 /min and the patient was still in a stuporous state .
preoperative laboratory data were within the normal range , and the chest x - ray revealed improvement of focal pneumonia and an arterial blood gas analysis in the tolerable range ( abga ; ph 7.418/paco2 39.5 mmhg / pao2 104 mmhg with 2 l / min oxygen inhalation ) .
an electrocardiogram ( ecg ) performed before the surgery showed sinus tachycardia , and transthoracic echocardiography revealed a preserved global left ventricular systolic function ( ejection fraction ; 69% ) .
the preoperative brain ct sacn showed a marked shrinkage of the left cerebral hemisphere and an increase in ventricular size ( fig .
the general anesthesia was induced with 125 mg thiopental sodium and 50 mg rocuronium , without any premedication .
the vital signs were monitored using noninvasive blood pressure ( nibp ) , ecg and a pulse oximeter .
the tracheostomy tube was changed for a 7.5 mm cuffed tracheostomy tube . following the induction of anesthesia ,
the right dorsalis pedis artery was cannulated with a 22 gauge catheter , and the right femoral vein was cannulated with an 18 gauge catheter .
general anesthesia was maintained with balanced anesthesia using oxygen - air - sevoflurane ( 0.51.5% ) and supplementary remifentanil ( 46 g / kg / h ) infusion .
cranioplasty was carried out under controlled ventilation , keeping within 10% fluctuation of the vital signs and etco2 with intermittent injections of ephedrine , phenylephrine and esmolol .
the abga was checked immediately after skin incision , and the results were a ph of 7.436 , paco2 35.1 mmhg , pao2 219.1 mmhg , and base excess 0.5 . intravenous fluid replacement consisted of 500 ml plasma solution and 50 ml lactated ringer solution , and the estimated blood loss was 200 ml .
after 2 hours of operation , the dura was closed , and the bony fragment was wired into place .
subsequently , drainage catheters were introduced into both the subgaleal and epidural spaces . by the time the scalp sutures were completed , a closed negative
approximately 30 seconds after suction drainage , sudden asystole of ecg , the disappearance of etco2 wave and a flat line arterial wave form were noticed .
instantly , the suction drainage was stopped , and we started external cardiac massage for approximately 20 seconds .
two times injections of 500 g epinephrine were administered under the diagnosis of cardiac arrest .
the cardiac rhythm was resumed to 120 bpm , and systolic blood pressure was regained to 150 mmhg immediately .
the abga was checked after resuscitation , and the results were in the normal range ( ph 7.418 , paco2 39.5 mmhg , pao2 103.3 mmhg and base excess 0.2 ) .
he went into a coma and showed partial spastic movement of extremities , suggesting a sudden increase in intracranial pressure ( icp ) .
2 ) revealed extensive diffuse brain swelling . due to the fact that there were no specific causes of brain edema during the operation or general anesthesia , the negative vacuum suction drainage was presumed to be the main cause , resulting in the patient being diagnosed with phbs .
the patient received agents to reduce icp , in addition to general supportive care with controlled ventilation .
he improved gradually in the nicu , and reached a stuporous state with self - respiration 3 months postoperatively .
van roost et al .   reported phbs as a newly defined complication after uneventful brain surgery .
the main clinical characteristic that appear on brain ct scans include brainstem dysfunction and diffuse brain swelling , especially involving the bilateral basal ganglia and thalami .
the main pathomechanism of phbs is assumed to be a decrease in icp due to sudden excessive depletion of cerebrospinal fluid ( csf ) .
an increase in icp can cause the cushing response , characterized by the occurrence of hypertension , bradycardia , and respiratory irregularities , resulting from the stimulus of pressure on the brainstem .
the opposite of the cushing response , intracranial hypotension , is also though to be a possible cause of circulatory changes such as bradycardia , hypotension and even cardiac arrest .
it is known that intracranial hypotension , induced by an extradural suction drainage system for the prevention of postoperative hematoma formation , may occur in neurosurgical procedures .
this iatrogenic intracranial hypotension may develop during or after variable neurosurgical procedures when applying negative suction pressure to extradural or epicranial drainage after craniotomy , after sudden decompression of hydrocephalus , or after spine surgery related to csf loss during the operation .
because the burr hole trephination and cranial bone incisions are not water proof , negative pressure subgaleal suction may provoke acute loss of the csf and a decrease in icp .
a rapid fatal case has been reported following a drainage volume of 100-ml csf . however
, a small loss of csf by gravity can cause phbs . after a loss of csf
, the brain can expand to fill up free space that was previously filled with gas and fluid including csf and exsanguinated blood .
the pathomechanism of bradycardic rhythm disturbances following intracranial hypotension was reported as a consequence of rostral migration of the brain or brainstem .
the pressure changes of the brainstem and hypothalamus can be caused by alteration of sympathetic outflow to induce lethal bradycardia , hypotension , or both . in the present case ,
firstly , there were no specific events during the entire anesthesia or operation , however , sudden severe bradycardia and cardiac standstill were noticed immediately after initiation of suction drainage through the subgaleal and epidural catheter . the exact amount of csf was not calculated . secondly , the postoperative brain ct scan showed diffuse brain swelling .
this patient already had shrunken brain hemispheres and a widened intraventricular space , and the negative suction pressure increased the free space after cranioplasty and could evoke a more diffuse brain swelling . we could postulate that this was the reason why severe phbs happened in this case . in conclusion , unexpected circulatory collapses such as hypotension , severe bradycardia , and cardiac arrest can develop following intracranial hypotension due to loss of csf through the negative suction drainage in variable neurosurgical procedures .
anesthesiologists and neurosurgeons should consider , be alert , and cope with potential perioperative circulatory collapses or clinical deteriorations related to phbs following intracranial hypotension in uneventful brain surgery .
 pseudohypoxic brain swelling ( phbs ) is known to be an uncommon event that may occur during and following an uneventful brain surgery , when negative suction drainage is used . 
 the cerebrospinal fluid loss related to suction drainage can evoke intracranial hypotension that progress to phbs . 
 the main presentations of phbs are sudden unexpected circulatory collapses , such as severe bradycardia , hypotension , cardiac arrest , consciousness deterioration and diffuse brain swelling as seen with brain computerized tomography ( ct ) . 
 we present a stuporous 22-year - old patient who underwent cranioplasty under general anesthesia . 
 the entire course of the general anesthesia and operation progressed favorably . however , the time of scalp suture completion , sudden bradycardia and hypotension occurred , followed by cardiac arrest immediately after initiation of subgaleal and epidural suction drainage . 
 after successful resuscitation , the comatose patient was transferred to the neurosurgical intensive care unit and phbs was confirmed using brain ct . 
Case Report
Discussion