An 87 y.o. male fell forward while gardening, he presented with epistaxis.
What do you notice on his CT?
Our patient had a lamina papyracea fracture and cribriform plate fracture resulting in extensive pneumocephalus. The lamina papyracea is the medial wall of the orbit and the lateral surface of the ethmoid air cells. The cribriform plate is the portion of the ethmoid bone that forms the roof of the nasal cavity. It is perforated by numerous holes which allow olfactory nerves to transmit odors to the brain.
looking down at the skull, the cribriform plate is a series of holes.
There are several complications of these frontal base of the skull fractures.
1. CSF leak- is the most common complication . CSF leak is diagnosed by analysis of the nasal fluid for a protein called beta-2 transferrin. A CT cisternogram can also be done by injecting contrast during a spinal tap.
2. Tension pneumocephalus can develop which is a neurosurgical emergency.The subdural air can cause a mass effect over the brain parnechyma often from a ball-valve effect allowing one way entry of air into the subdural space. The presence of air between the frontal tips suggests that the pressure of the air is at least greater than that of the the surface tension of CSF between the frontal lobes. This is known as the Mt Fuji sign and can be seen on CT.
The Mount Fuji sign refers to the “V” shape between the frontal lobes.
3. Long term problems – following fractures pseudoanursym of the internal carotid or carotid cavernous fistula, meningitis, anosmia, or optic nerve ischemia can develop.
BEWARE THE CRIBRIFORM P:LATE: it may be fractured during trauma and lead to intracranial placement of an NG tube.
Causes of pneumocephalus include:
TRAUMA- with a base of the skull fracture
RECENT SURGERY- It is estimated 2.5% of patients will develop pneumocephalus after a chronic subdural evacuation
TUMORS OF THE PARANASAL SINUSES- even pituitary tumors that regress with treatment can cause a connection between the subdural space and the nasal cavity.
INFECTIONS
THE USE OF NITROUS OXIDE- NO dissolves into blood and enters the subdural space , expanding the pre-exisitng gaseous volume during anesthesia.
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Himeno T, Takeshima S, Kubo S, et al. Tension pneumocephalus complicated from bacterial meningitis- a report of case presenting “Mount Fuji sign” in brain CT. Case Reports 2013;53(6):478-81. In this case a fistula developed between the infected sphenoid sinus and the subdural space.
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