SINUSITIS



The sinuses are bubbles in the bones of our skull. They make our voices deeper. Mucus is also made inside of them, which drains into our nose. If the drainage pipe gets clogged up (often from a viral URI, or from allergies), the mucus pressure builds inside the sinus. That hurts. Stagnant fluid always gets infected, and the sinus is no exception. So they have a fever. 


Most sinuses have drainage holes at the bottom of the bubble; however, the maxillary sinus is the exception. Its ostia is at the top, so it has to fight against gravity to feed mucus into the nose. It drains through the middle meatus (the superior meatus drains the sphenoid/ethmoid, the middle meatus drains the maxillary/frontal/ethmoid, and the inferior meatus drains the nasolacrimal duct). Interestingly, humans have evolved a relatively flat face that makes maxillary drainage difficult, hence our predisposition to sinusitis. 


Sinusitis can be either viral or bacterial. You should suspect a bacterial cause if the infection (a) has lasted over 10 days, (b) has gross yellowish snot and (c) has a fever. The most common bugs are Strep pneumoniae (most common), H. influenzae and M. catarrhalis. After waiting through 10 days of symptoms, you should treat with Amoxicillin (for the first infection) or Amoxicillin / Clavulanate (if the Amoxicillin doesn’t work). 


The sinuses are adjacent to the orbit and brain. Serious untreated infections can sneak into those places, causing orbital cellulitis, cavernous sinus syndrome or meningitis.  

Left maxillary sinusitis on a CT scan




UPPER RESPIRATORY INFECTION

A common cold


A URI is a loosely defined term referring to an infection of any respiratory tract tissue above the trachea (nose, throat, larynx).  Usually viral. 

Here are some symptoms that most URIs share: fever, chills, congestion, sore throat, fatigue and malaise. URIs are mild, benign conditions. They typically improve in a few days. The only one we treat with antibiotics is strep throat, because we want to prevent rheumatic fever. Usually, the causative virus is never identified. But it’s common practice to test for COVID, influenza, mononucleosis and strep throat, as these four illnesses possess possible complications. 


You can break down a URI into the different types of tissue of the ENT system. 


Rhinitis is an infection in the nasopharynx. Aka the common cold. It can commonly spread to the sinuses, and when it does, the infection becomes “rhinosinusitis.” Rhinitis causes a runny nose and sneezing. The nasal congestion can drip down the back of the throat, and for some reason this irritates the throat, and causes a mild sore throat. Causative agents include Rhinovirus (duh), Influenza virus, RSV, Parainfluenza virus, Adenovirus and some Bacteria (Strep pneumo, H influenzae, Moraxella catarrhalis, Staph aureus).


Pharyngitis refers to a sore throat. Rhinovirus, Coronavirus and EBV are common viral causes (75% viral). Strep pyogenes is the most common bacterial agent (strep throat). It causes an isolated sore throat and fever, plus a red inflamed throat coated in while exudative plaques. 


Tonsillitis is a tonsil infection. Clinically it is quite similar to pharyngitis, although on exam the inflammation is located on the tonsils more than the throat.


Laryngitis is an infection of the larynx (voice box). Usually viral. Laryngitis causes a hoarse voice and dry cough. 

EPISTAXIS

Nose bleed


There are two kinds of nose bleeds. Ones that bleed backwards down the throat (posterior) and ones that only bleed out of the nostrils (anterior). 


Anterior nosebleeds are better. They’re easier to treat and rarely have any serious complications. They usually occur at a vascular plexus in the nose called Keisselbach’s Plexus. Since this structure is pretty close to the nostrils, you can staunch the flow of blood by pinching your nose. 


Posterior nosebleeds are kind of a big deal. They’re difficult to treat and can cause aspiration (when the blood pours down the throat). They usually start at the Sphenopalatine artery (a branch of the Maxillary artery). You can’t stop the blood flow by pinching your nose. Patients must be advised to lean their heads forward, else the blood drips down their throat and into their stomach or lungs. Treatment involves some complicated tools to either compress (balloon) or cauterize (silver sticks) the source. 



Nose bleeds are usually caused by nose picking, dry air, or allergies. Less common causes include facial fractures, platelet disorders or nasal angiofibromas.




INFLUENZA

The flu


The Influenza virus causes the flu, an acute respiratory illness during the winter which is transmitted by respiratory secretions. The patient will complain of flu-like symptoms, including  a fever, chills, runny nose, cough, myalgias, malaise, sore throat and headache. Beyond the annoying symptoms, the flu itself is pretty benign. The problem is that the flu can stun the mucociliary elevator, and predispose to a superimposed pneumonia (classically Staph aureus). Secondary pneumonia can be fatal, especially in the elderly. The CDC estimates that the flu kills about 400,000 people every year (FYI coronavirus has killed 1,200,000 so far). 


Here’s a list of the random micro facts.


These H and N antigens are fairly mutagenic, and so they like to change. The gradual accumulation of genetic variations is called genetic drift. Although it doesn’t cause dramatic pandemics (like shifts do), drifting is really important because it prevents us from making a good vaccine against the flu, since it helps the flu gradually change year-to-year. That’s why getting the flu only protects you from the flu for the next 1 - 3 years. 


Antigenic shift is like a flu-Frankenstein. It happens when someone gets infected with two very different strains (swine flu AND human flu). There will be cells that are double-infected. As the infected cells synthesize and package up their virion progeny, they end up mixing the two virus segments together (this mixing is only possible because of segmentation). They create a virus strain that’s 50% swine flu and 50% human flu. This is a radically new virus, and no one in the world has antibodies to it yet. That’s why it can cause pandemics (like the Spanish Flu of 1918). Fun fact, Flu B can only infect humans and seals, so antigenic shifts don’t occur with B. So don’t eat any seal meat. 


Treat with Neuraminidase inhibitor (Oseltamivir). Oseltamivir doesn’t stop the virus from infecting cells or making new viron progeny, but it does block the release of progeny from the human cells -- essentially locking them inside like a prison. It only works if started within 48 hours of symptoms, and it may shorten the duration of symptoms by like 12 hours. Side rant - this drug doesn’t do shit. And it costs $300. Big pharma at its finest. Sources 1 and 2


Towards the end of every flu season, the WHO predicts which strain of the flu will be the biggest during next year’s season. Scientists spend the “offseason” developing vaccines to the most likely 5 - 10 strains. Since there’s an element of guesswork involved, the Flu Vaccine has variable effectiveness. Some years it works 90% of the time, other years only like 20% effective. But it is extremely safe. It’s grown in eggs. The killed vaccine is the standard “flu shot.” The live nasal spray vaccine is also available, though it’s much less popular. It’s a mutant flu strain that only replicates in the nose. Sometimes given to needle-phobic kids.  

CROUP

Viral laryngotracheobronchitis


Croup is a very distinctive URI that only occurs in kids 6 months - 3 years old. It’s pretty darn common. The child will present with an unmistakable brassy cough that sounds like a barking seal.  They also can have inspiratory stridor. Stridor is usually a medical emergency, but Croup is the one exception to that rule. Croup usually self-resolves, but severe cases can be treated with steroids. 


Croup is an infection of the upper trachea (as well as the larynx and bronchi) by the Parainfluenza virus, a member of the Paramyxovirus family along with RSV, Measles and Mumps. (Note - it’s called PARA-influenza because it also has Hemagglutinin and Neuraminidase antigens). Croup causes the upper trachea to narrow, and this can be seen on a CXR as a “steeple sign.”

Steeple sign - narrowing of the upper trachea




EPIGLOTTITIS

Throat flap infection


The Epiglottis is a flap in the throat separating the air hole (larynx and trachea) from the food hole (esophagus). When we breathe, it lifts up, exposing the larynx. When we eat, it descends, closing the entrance of the larynx. 


Epiglottitis technically refers to any  inflammation of the flap, but in practice Epiglottitis always refers to a bacterial infection, usually in a child. Since the epiglottis routinely obstructs the airway during its normal functioning, you can imagine how an infection could be devastating. It would make the epiglottis swollen and stiff, which could block the trachea partially (stridor, hot-potato voice) or completely (asphyxiation). Also, there’s a high fever. They like to sit in the tripod position, because it pulls their tongue and epiglottis forward. 


Epiglottitis is a medical emergency. It starts fast and worsens rapidly. Your first priority is maintaining the airway, so call anesthesia so that they can intubate this kid. Tracheostomies / Cricothyroidotomies are other options. The second priority is rapid administration of antibiotics and steroids. 


Epiglottitis used to be a really common disease (it killed George Washington). The vast majority of cases were caused by type B Haemophilus influenzae, but thankfully, the Hib vaccine was created. It has nearly eliminated epiglottitis in the developed world (among vaccinated kids, at least). I say nearly, because sometimes non-type B H. influenzae can cause epiglottitis. Strep pyogenes can also infrequently cause it. 


The diagnosis is made with a lateral XR of the neck, looking for a swollen epiglottis (often described as having a thumb-like appearance). When you look at the epiglottis during intubation, the flap appears swollen and cherry red. 

Healthy Epiglottitis




SLEEP APNEA

Pauses in breathing


Sleep Apnea is exactly what it sounds like. You periodically stop breathing during sleep. 


What are the subtypes?

Obstructive - Obese patients have fat necks. When they sleep, the weight of their adipose tissue overwhelms their pharyngeal muscles and squishes their airway. Once their brain starts to starve, it screams at the pharyngeal muscles to open up, and the patient will have a loud, dramatic, snoring-like inhale. This often wakes patients up in the middle of the night, interrupting their march towards REM sleep. Then they’re sleepy during the day. It can also be caused by huge tonsils in kids. 


Central - Less common than Obstructive SA. It occurs when neurological pathways responsible for breathing are damaged (eg, brainstem damage) or sedated (eg, opioids). The brain fails to notice as their blood becomes hypoxic during the night. Look for Cheyne-Stokes respirations (a crescendo-decrescendo waveform breathing pattern)

Cheyne-Stokes respirations


Why is sleep apnea bad?

Because it makes you hypoxic. Then the hypoxia ramps up your Sympathetic drive. That increases your HR and BP. Combined with the lack of good sleep, this hypoxic damage and sympathetic overdrive can cause Hypertension. There’s a well-established correlation between sleep apnea and HTN, CHF, CAD, arrhythmias and increased mortality! 


Treatment?

Use a CPAP machine (Continuous Positive Airway Pressure) while they sleep. The CPAP machine maintains a positive pressure in the mouth, pharynx and trachea while you sleep. That prevents the throat from closing up. It’s cumbersome and uncomfortable, so many patients won’t use it.







Pickwickian Syndrome is seen in morbidly obese patients who have difficulty expanding their ribs to breathe day and night. They especially under-ventilate during the night, which can cause some sleep-apnea-like consequences. Their ABGs show hypercapnia and hypoxemia.



LARYNGOMALACIA

Laryngo- (larynx) -malacia (softening)


Laryngomalacia is a congenital softening of the voice box. Specifically the aryepiglottic folds are shortened. That pulls the epiglottis into an unhelpful omega shape. Additionally, all of the laryngeal tissue is floppy. So everytime the patient breathes in, the epiglottis is pulled down into the larynx (instead of covering it up). 


Laryngomalacia is one of the most common causes of inspiratory stridor in young children. Although the diagnosis peaks around 1 year old, it usually resolves spontaneously by the time the child turns 2 years old. No treatment is usually required, although surgery is sometimes indicated if it persists.




Notice how the Epiglottis is shaped like an upside down “U” or omega “Ω.”