Pneumocephalus
Encyclopedia
Pneumocephalus is the presence of air or gas within the cranial cavity
. It is usually associated with disruption of the skull
: after head and facial trauma
, tumors of the skull base, after neurosurgery
or otorhinolaryngology, and rarely, spontaneously. Pneumocephalus can occur in scuba diving, but is very rare in this context.
If there is a valve mechanism which allows air to enter the skull but prevents it from escaping, a tension pneumocephalus can occur (similar to what can happen in a tension pneumothorax).
CT scans of patients with a tension pneumocephalus typically show air that compresses the frontal lobes of the brain, which results in a tented appearance of the brain in the skull known as the Mount Fuji sign.
The name is derived from the resemblance of the brain to Mount Fuji
in Japan
, a volcano known for its symmetrical cone. In typical cases, there is a symmetrical depression near the midline (such as the crater of a volcano), due to intact bridging veins. Its occurrence seems to be limited to tension pneumocephalus (not occurring in pneumocephalus without tension). The sign was first described by a team of Japanese neurosurgeons.
Cranial cavity
The cranial cavity, or intracranial space, is the space formed inside the skull. The brain occupies the cranial cavity, which is lined by the meninges and which contains cerebrospinal fluid to cushion blows....
. It is usually associated with disruption of the skull
Human skull
The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...
: after head and facial trauma
Facial trauma
Facial trauma, also called maxillofacial trauma, is any physical trauma to the face. Facial trauma can involve soft tissue injuries such as burns, lacerations and bruises, or fractures of the facial bones such as nasal fractures and fractures of the jaw, as well as trauma such as eye injuries...
, tumors of the skull base, after neurosurgery
Neurosurgery
Neurosurgery is the medical specialty concerned with the prevention, diagnosis, treatment, and rehabilitation of disorders which affect any portion of the nervous system including the brain, spine, spinal cord, peripheral nerves, and extra-cranial cerebrovascular system.-In the United States:In...
or otorhinolaryngology, and rarely, spontaneously. Pneumocephalus can occur in scuba diving, but is very rare in this context.
If there is a valve mechanism which allows air to enter the skull but prevents it from escaping, a tension pneumocephalus can occur (similar to what can happen in a tension pneumothorax).
CT scans of patients with a tension pneumocephalus typically show air that compresses the frontal lobes of the brain, which results in a tented appearance of the brain in the skull known as the Mount Fuji sign.
The name is derived from the resemblance of the brain to Mount Fuji
Mount Fuji
is the highest mountain in Japan at . An active stratovolcano that last erupted in 1707–08, Mount Fuji lies about south-west of Tokyo, and can be seen from there on a clear day. Mount Fuji's exceptionally symmetrical cone is a well-known symbol of Japan and it is frequently depicted in art and...
in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, a volcano known for its symmetrical cone. In typical cases, there is a symmetrical depression near the midline (such as the crater of a volcano), due to intact bridging veins. Its occurrence seems to be limited to tension pneumocephalus (not occurring in pneumocephalus without tension). The sign was first described by a team of Japanese neurosurgeons.