2/Calvarium & sinuses act as important protectors of your intracranial contents, most importantly, your brain. They are like a built in helmet to protect you from linebackers of life
3/The sinuses are actually even better than a helmet. They are like the crumple zone of a car, but for your brain. They can be crushed inwards, absorbing energy and keeping it from impacting your brain
4/The crumple zone of the frontal sinus is like a sandwich. First, the top bread, is the anterior wall. The meat/filling is the sinus itself & sinus drainage pathway. Finally, the bottom bread is the posterior wall. Each of these can be affected by trauma.
5/First is the anterior wall. Usually, a significant trauma is required to break the anterior wall of the frontal sinus, as it forms the frontal bar, supporting the facial buttresses.
6/You can think of an anterior wall fx like a fender bender. The front of the car is damaged, but everything else is intact. Fixing a fender bender is all about cosmetics. Anterior wall fxs are fixed if they are depressed bc having a dent in your forehead is very noticeable.
7/Next is a fx that affects the meat, or the sinus itself. Any medial fx that affects the ability of the sinus to drain into the ethmoids or significantly disrupts the muscosal elements will make the sinus unable to drain and susceptible to mucocele formation.
8/Fxs that obstruct the drainage pathway or mucosal elements are like car accidents that wreck your engine. A car needs to drive & a sinus needs to drain. If they can’t, they are worthless. So a car goes to the junk yard & a sinus gets obliterated. Tx is sinus obliteration.
9/Finally, posterior wall fxs. Posterior wall fxs are dangerous if they disrupt the dura & therefore cause a communication between the brain & the outside—bc this can cause infection. Signs that the dura have been violated are extra-axial blood or pneumocephalus.
10/Posterior wall fxs are like an accident that breaks your windshield. Now all that air is free to flow into the car—like the air from the sinus, potentially containing bacteria, can flow into the intracranial compartment
11/You will never get that seal back. The treatment is cranialization—kind of like turning the car into a convertible.
12/Here is the algorithm for treating frontal sinus fxs.
Anterior wall only = fixation for cosmetic.
Fx affecting sinus drainage = junk the sinus/obliteration.
Fx of the posterior wall w/risk for infxn = take the top off/cranialization.
13/Based on the treatment algorithm, radiology reports must reflect findings that change management.
Depression/comminution of ant wall fx=need for ORIF
Findings of violation of the dura=need for cranialization
Findings of nasofrontal duct obstruction=need for obliteration
14/So here is a summary of the frontal sinus fractures and their management. Hopefully, when it comes to frontal sinus fractures, this tweetorial will help you save face and stay a head of the game!
• • •
Missing some Tweet in this thread? You can try to
force a refresh
2/When it comes to brachial plexus injuries, the most important distinction to make is whether it is a pre or post ganglionic injury. Pre ganglionic injuries are nerve root avulsions from the spinal cord and cannot be repaired, while most post ganglionic injuries can be repaired
3/It’s like repairing a house. If there’s a structural flaw at the beginning, before you’ve even built it, you won’t even try to build it, you’ll just scrap the design (preganglionic). But if there’s damage after the house is built, you can salvage it w/repair (postganglionic)
2/Brachial plexus is how the cervical nerves reach the arm. In the coronal plane, it looks like a slide, guiding nerves downward. Bc nerves are traveling laterally, sagittal MRI plane is our plane of choice to cut the nerves in cross section & see down the barrel of the nerves
3/But it’s more than a slide, it’s a complex highway, w/nerves joining & dividing—like highway off ramps & on ramps. If you want to know more about this intrinsic anatomy, see my first brachial plexus tweetorial here:
2/Everyone has a mnemonic to remember brachial plexus anatomy. I’m a radiologist, so I remember one about Rad Techs. But just remembering the names & their order isn’t enough. That is just the starting point--let’s really understand it
3/From the mnemonic, we start with the roots—the cervical nerve roots. I remember which roots make up the brachial plexus by remembering that it supplies the hand. You have 5 fingers on your hand so we start with C5 & we take 5 nerve roots (C5-T1).
1/ Talk about dangerous liaisons! Abnormal brain vascular connections can be dangerous
A #tweetorial about an important abnormal connection: dural arteriovenous fistulas (dural AVF) in collaboration w/ @SVINJournal!
2/Dural sinuses sit inside dural leaflets. Arteries that feed the dura also feed the walls of sinuses, like vasa vasorum. Arteries in the walls of veins are a natural connection between the veins and arteries—but these connections are usually closed in normal pts.
3/Whether these connections are open depends on pressure. Like a hose w/a hole in it, at normal pressures, abnormal connections are not open. But if pressure is increased w/thrombosis or stenosis, the connections open, like high pressure water squirting out through a hole.
1/Sometimes the tiniest thing can be the biggest pain—that’s microvascular compression of the trigeminal nerve! But seeing such a tiny finding can be hard!
2/The most important thing to remember is that the nerve is 3D so you have to look for compression in all 3 planes. Let’s start w/the axial plane. On a normal axial, the trigeminal nerves should look like the arms of an alien sticking out of the pons.
3/Compression in the axial plane usually will deviate the nerve laterally—making it so that the Alien looks like he is flexing one of his arms. So if you see the Alien trying to show his guns—that’s microvascular compression!
2/A is for alignment. Normal spinal alignment is perfectly in balance, resulting in the minimal energy needed for erect posture. Even subtle changes in alignment need compensatory changes to maintain posture, resulting in more work/energy expenditure & pain.
3/The goals for alignment on imaging: (1) look for unstable injuries & (2) look for malalignment that causes early degenerative change. Abnormal motion causes spinal elements to abnormally move against each other, like grinding teeth wears down teeth—this wears down the spine