intracranial foreign bodies frequently result from trauma , including penetrating injury , and rarely involve wooden materials compared with metallic materials .
when intracranial penetrations of wooden objects occur through the transnasal or transorbital route , physical examinations may reveal no abnormalities , and the objects may be difficult to visualize with conventional radiography .
we present a case involving the transnasal intracranial penetration of a wooden branch that resulted in a delayed intracranial infection due to initial misdiagnosis .
a 48-year - old man presented to the emergency department with complaints of headache the day before .
two days earlier , he fell to the ground in a drunken state , and he could not clearly remember the incident . at the emergency department , no neurological or physical abnormalities , such as external contusions or cerebrospinal fluid rhinorrhea , were observed .
computed tomography ( ct ) that was performed upon admission showed a round hypodense signal in the left frontal area , which suggested pneumocephalus , and a small amount acute subdural hematoma in the left frontotemporoparietal area ( figure 2 and 3 ) .
the patient was admitted to the neurosurgical department for close observation , and prophylactic antibiotics were administered for the pneumocephalus .
brain magnetic resonance imaging ( mri ) revealed a fistula from the left nasal cavity to the frontal lobe with enhancement along the tract and ventricular lining ( figure 4 ) .
the foreign body was a wooden branch ( 11 cm long and 0.7 cm wide ) covered with brain tissue ( figure 5 ) .
after the operation , the patient received intravenous antibiotics ( ceftriaxone plus vancomycin ) for over 2 months . a microbiologic culture study on the foreign body showed gram - positive cocci ( s. aureus ) .
intracranial penetrating injuries by foreign bodies represent only 0.4% of all head injuries and usually occur in children because of falls.17 ) intracranial foreign bodies that cause severe intracranial infections can be fatal.8 ) miller et al.7 ) reviewed 42 cases with intracranial penetrating injuries and found that 64% developed central nervous system infections , 45% had additional brain abscesses , and the death rate was 25% . generally , the time from the injury to the clinical intracranial infection presentation is long , but it can vary from a few days to several years.5 ) therefore , careful history taking and thorough physical and radiologic examinations are essential . however , intracranial wooden foreign bodies are difficult to detect with plain radiographic techniques and distinguish from periorbital fat and air in the nasal cavity on ct images.48 ) the ct attenuation values of wooden foreign bodies vary depending on their water content .
freshly cut wood has a relatively high physical density because of its high water content ; therefore , it is difficult to distinguish it from soft tissues , such as muscle and vitreous.3 ) conversely , when wood dries , the water is gradually replaced by gas , and its density is difficult to distinguish from that of fat or air.3 ) consequently , intracranial wooden foreign bodies have variable densities over time and are difficult to distinguish from the surrounding structures .
tasneem et al.11 ) described a case involving a radiolucent intracranial wooden foreign body and the usefulness of the lung window setting for detecting wooden foreign bodies on ct images .
careful review of ct images with the lung window setting can be helpful for detecting a wooden foreign body . unlike ct images , mri is more useful for detecting wooden foreign bodies that appear hypointense on t1- and t2-weighted mri scans and that can be distinguished from air or fat.69 ) in addition , infected lesions exhibit gadolinium enhancement .
the initial ct image of the patient showed a single area of air in the frontal lobe .
steudel and hacker10 ) reviewed 508 cases with acute head injuries and found that 49 ( 9.7% ) had a pneumocephalus on brain ct scans , with 5 ( 1% ) showing a single air bubble and 6 ( 1.1% ) having an intracerebral or intraventricular location .
however , they did not experience a case involving a single air bubble with an intracerebral or intraventricular location .
these findings suggest that patients with a pneumocephalus with a rare presentation need to be examined more carefully .
patients with retained intracranial wooden foreign bodies frequently develop delayed infectious complications , and surgical removal is necessary , even in the absence of symptoms.178 ) our patient experienced late - onset seizures , which could have been secondary to gradual gliosis , progressive granulomatous changes , or delayed abscess formation , as has been noted in cases with retained foreign bodies.2 ) therefore , if intracranial injury from a wooden foreign body is suspected , careful history taking and imaging are very important .
once the diagnosis of an intracranial foreign body is confirmed , surgical removal of the foreign body is required .
the present case illustrates the necessity for special attention to patients suspected of having pneumocephalus with a rare presentation during the initial examination . early surgical removal of the intracranial foreign body is necessary to prevent complications .
 intracranial wooden foreign bodies are rare . in addition , such objects are difficult to identify with conventional radiographic techniques , such as x - ray radiography or brain computed tomography . a 48-year - old man presented to our emergency room with a headache . 
 even though he had a history of trauma , he had no external wounds and showed no neurological deficits at the initial examination . 
 he was initially diagnosed with trauma - related pneumocephalus . 
 he developed a delayed intracranial infection and underwent surgery to remove the wooden foreign body . 
 the present case illustrates the necessity for special attention to patients suspected of having pneumocephalus with a rare presentation during the initial examination . 
 early surgical removal of the intracranial foreign body is necessary to prevent complications . 