a 50-year - old , 168 cm , 68 kg man without significant past medical history , was admitted to emergency room following a slip - down accident . on admission , neurologic examination confirmed a glasgow coma scale ( gcs ) of 15 , and the pupils were symmetrical and reactive . emergent skull x - ray series , facial computerized tomography ( ct ) and forearm x - ray revealed fracture of the frontal sinus , skull base , and right distal radius fracture . computed tomography ( ct ) of the brain showed multiple small subdural pneumocephalus ( fig . emergent lumbar drainage was performed to manage csf rhinorrhea and empirical prophylactic antibiotic treatment was given . the patient 's post - traumatic symptoms improved gradually in the surgical intensive care unit . at post - trauma 8 days , following trauma , the patient underwent orthopedic surgery for distal radius fracture under general anesthesia . anesthesia was induced with intravenous thiopental 300 mg and 0.5 g / kg / min remifentanil infusion . endotracheal intubation was performed after administering 50 mg rocuronium injection with 100% oxygen mask ventilation for 3 min without any difficulties . anesthesia was maintained with oxygen ( 2 l / min)-air ( 2 l / min)-sevoflurane ( 1 - 1.5 vol% ) , continuous infusion of 0.125 - 0.5 g / kg / min remifentanil and 10 - 15 mg / h of rocuronium . tidal volume and respiratory rate were adjusted to maintain end - tidal carbon dioxide tension at 30 - 35 mmhg . following surgery , the patient was extubated in the operation room after gaining consciousness and spontaneous ventilation . he was then transferred to the post - anesthesia care unit where he recovered fully without complications . ten hours later , the patient complained of severe , increasing , headache and exhibited abrupt deterioration in mental state . in view of his clinical aggravation , neurologic examination demonstrated a gcs 11 and emergent brain ct showed large quantity of both frontal and right occipital pneumocephalus ( fig . high flow ( 8 l / min ) oxygen via a partial non - rebreathing mask was administered in conjunction with supportive care for 2 days . no infectious neuromeningeal complications occurred during hospitalization , and the patient was discharged at post - trauma day 32 . it develops mostly from acute and subacute complications of head trauma , or as late complications during the recovery phase of head injury . subarachnoid or subdural air accumulation is the most common form of pneumocephalus , and intracerebral pneumocephalus can occur albeit rarely . intracranial air is accumulated as a result of communications between paranasal sinuses , mastoid air cells and the cranial fossa , associated with dural tear . the other mechanism of air penetration is a ball - valve effect like sudden increase of nasopharyngeal pressure , such as during coughing and sneezing , forcing air into the cranial cavity which subsequently remained trapped . injuries of the paranasal sinuses , which are closely contiguous to bony structures , the dura mater and the brain frequently accompany head traumas . 75 - 90% of pneumocephalus are posttraumatic and the incidence of pneumocephalus secondary to head injury range from 0.5% to 13.2% . other causes include facial tumors that eroded through the skull , gas - forming bacterial infections , paranasal sinusitis and neurosurgical and facial procedures . pneumocephalus is mostly asymptomatic and self - limiting , because gas is not irritating to the surrounding brain . intracerebral pneumocephalus have usually become sizable when it is confirmed by simple skull x - ray or brain ct . tension pneumocephalus caused by large amounts air can evoke sudden or insidious mass effects capable of shifting midline structures , causing major neurological deficits . representable iatrogenic pneumocephalus are related to positive pressure ventilation in the upper airway , such as nasal continuous positive airway pressure , face mask ventilation and even nasal oxygen cannulae . it is well known that positive airway pressure can result in pneumothorax , pneumomediastinum and subcutaneous emphysema . it is difficult to predict which head trauma patients who do not initially develop pneumocephalus will experience iatrogenic pnemocephalus during positive pressure oxygen therapies . the mechanism of air delivered via manually operated mask tracking into the cranial cavities appears to be identical to that in traumatic pneumocephalus . because csf leakage is usually a result of osteomeningeal fistula , csf rhinorrhea is commonly associated with pneumocephaus , as demonstrated in this patient . his initial primary pneumocephalus accompanied by rhinorrhea was completely subsided following lumbar drainage and general supportive care , but post - anesthetic secondary pneumocephalus probably developed during anesthesia induction using ppmv . therefore , avoidance of excessive positive pressure during mask ventilation is recommended to prevent pneumocephalus . because most mild pneumocephalus usually recover spontaneously within one week , its management includes strict bed rest in the semi - fowler position , analgesia and antibiotics . prevention of intracranial pressure elevation by avoiding the valsalva maneuvers , coughing , sneezing , nose blowing , and excessive physical activities is important to avoid pneumocephalus aggravation . because severe headache , personality change , disorientation , and mass effect associated with midline structure shift are the symptoms and signs of tension pneumocephalus , emergent surgical procedures , such as subdural drainage to decrease intracranial pressure , should be considered immediately after confirming the diagnosis with x - rays or brain ct . when the patient experienced severe headache and became rapidly lethargic , analgesia , antibiotic and high flow , high fio2 oxygen via a partial non - rebreathing reservoired mask were administered under a presumed diagnosis of impending tension pneumocephalus . the management principle is as follows : high fio2 oxygen reduces blood and brain tissue nitrogen concentration , thereby increases the nitrogen concentration gradient that promotes pneumocephalus gas absorption . to avoid tension pneumocephalus in head trauma patients , lma or tracheostomy tube intubation in addition , anesthesiologists should be aware of potential complications caused by low intracranial pressure during anesthesia in head trauma patients . in theory , hypotension , hypovolemia , excessive hypercapnia and head - up position during anesthesia can reduce intracranial pressure that facilitates air influx through open osteomeningeal fistulae secondary to head trauma , causing pneumocephalus . in conclusion , anesthesiologists and surgeons should be aware of pneumocephalus as a potential complication during positive pressure mask ventilation for facial trauma , secondary to air invasion through osteomeningeal fistulae . close monitoring for pneumocephalus development should be mandatory following general anesthesia or during respiratory care with continuous positive airway pressure in head trauma patients .
pneumocephalus is a condition which usually results from head trauma . 
 it has been known that iatrogenic pneumocephalus can occur as a complication of positive pressure mask ventilation during induction of anesthesia or ventilatory care for head trauma patients . 
 we report a case of mask ventilation during anesthesia induction in a 50-year - old male patient with head trauma . 
 initial pneumocephalus associated with cerebrospinal fluid leakage was diagnosed immediate following head injury involving facial sinuses . 
 he was managed with emergent lumbar drainage and supportive care . 
 pneumocephalus recurred following positive pressure mask ventilation ( ppmv ) during anesthesia induction for surgery on the right arm . 
 recurred pneumocephalus was managed with high flow oxygen and supportive care . 
 anesthesiologists should be aware of pneumocephalus as a potential complication of ppmv in head trauma patients , even after resolution of previous pneumocephalus .