EMG and NCS - Review

Hello there!

Today we'll see some important points on Electromyography (EMG) and Nerve conduction studies (NCS).

EMG evaluates abnormal electrical activity in muscles, and NCS investigates how electricity flows through a nerve.

They help to locate and determine the causes of diseases that affect muscles and peripheral nerves.

Procedure:
In EMG, a small needle is inserted into a muscle, to measure its electrical activity. In NCS, electrodes are placed on the skin overlying a nerve, and other recording electrodes are attached at a different point over the same nerve and a small shock is applied, and the electrical impulse is recorded​.

Understanding the terminologies and results of these tests-

 Amplitude: The electrical signal is represented as a wave, and the amplitude is its height.

ConductionVelocity (CV): The conduction velocity describes the speed at which the electrical impulse travels along the nerve.D

Duration This describes the width of an electrical wave.

ConductionBlock: The diminution of signal across an anatomical region such as the wrist. This suggests nerve entrapment.

So when a nerve stimulates a muscle to contract, there is a brief burst of electrical activity called a motor unit action potential (MUP).

Some of the abnormal responses seen are:

1)Fibrillations & positive sharp waves on the monitor seen in diseases of peripheral nerves.

Muscles sometimes start having spontaneous activity on their own.

2)Fasciculations: Sometimes the abnormality causes visible muscle twitches.

3)Abnormally large MUPS : These are seen If a nerve has been injured and then regrows.

 On regeneration the nerve tends to branch out to include a wider area of the muscle and hence we get large motor unit potentials on the screen.

4) Abnormally small MUPS: When they're  abnormally small or brief it suggests the presence of a disease of a muscle (a myopathy) where the muscle is unable to contract to and fails to provide the normal amplitude of the wave.

5)"Recruitment pattern":  As a muscle is contracted, nerve fibers signal more and more bits of muscle (called motor units) to join in and help. 

In a neuropathic disorder, the amplitude of different motor units is strong, but there are fewer of them because the nerve is unable to connect to as many units.

 In myopathies, the number of motor units is normal, but the amplitude is smaller

You may never come across an actual EMG for an interpretation,but it is always good to know the investigation.

The interpretation of EMG and NCSs is not always straightforward and may not always lead to just one possible diagnosis — but the tests can reduce the number of diagnostic possibilities.

Hope this was helpful!

Let's Learn Together!

-Medha.

New TB Risk Factor

People with low levels of vitamin A who live with individuals who were sick with tuberculosis were 10 times more likely to develop the disease than people with high levels of the nutrient, according to research led by investigators at Harvard Medical School.

Vit A rich foods: Liver, fish, hard-boiled egg(not omelette), cheese, butter, cheddar etc

And now some vegetables: Sweet potato, Carrot, Squash, Spinach, Lettuce

Some fruits: Mango, Papaya, Guava, Watermelon, Apricot, Passion fruit

Another reason to love Mango!

-VM

Research update: Statins may increase risk of Parkinsons' disease

Hey Awesomites

A new research by neuroscientists has updated our knowledge about the association between high cholesterol levels in people and prevalence of neurodegenerative diseases such as the Parkinson's.

Mind - wandering : How your body reacts to it?

Hey Awesomites

First lets have a word about mind - wandering.. "Mind- wandering (or task-unrelated thoughts) is an experience of thoughts which are totally unrelated to the task you are doing right now, especially when it demands attention. It involves activities such as reading, driving, attending lectures, etc."

Dibucaine Number.

Hello !
Let's see what this Dibucaine number is.

So Dibucaine is a local anesthetic.

Dibucaine inhibits 80% of the normal Pseudocholinesterase enzyme and 20% of the Atypical enzyme.

The number is determined by measuring the percentage of Pseudocholinesterase enzyme that remains unchanged in the blood of individuals administered a standard dose of Dibucaine intravenously.

Normal Dibucaine number is 70-80% i.e 70-80%of normal enzyme is inhibited by Dibucaine.
If there is a point mutation in the enzyme making it a Atypical Pseudocholinesterase then Dibucaine will not be able to inhibit it and the number will decrease.

This number is used to measure the activity of Atypical Pseudocholinesterase,and to assess the likely hood of prolonged apnea after succinylcholine administration.

Sodium Fluoride can also be used in place of Dibucaine.

If you know more on it Add to this information.

Let's learn Together!
-Medha.

Contraindications for Noninvasive Ventilation Mnemonic

Hey guys

This is one of my rare mnemonic posts. I don't post much on this coz most of my mnemonics are kinda personal if not socially inappropriate :p

So Noninvasive ventilation, imagine having a mask on ur face, all air tight, almost strangulating and as if this isn't enough, with multiple tiny outlets giving jets of air which are titillating your highly itchable nasal area.

Unpleasant, right?

Talking of unpleasant, you do remember Hitler, right?
He GAAASED the Jews, since that's not a possibility for us since we all love Zuckerberg let's think about something on a similar note.

"GAAAS the HOEs"

G- GI bleeding
A- Aspiration
A- Angina( including MI)
A- Arrest( Cardiac and Respiratory)
S- Surgery on ur face

H- Haemodynamic instability
O- Obstruction ( in upper airway)
E- Encephalopathy ( Severe)
S- _____

I've left the last one blank for the reader to fill up. Hint: It has something to do with​ obstruction of the lower airways.

Hope this is helpful!

-VM

Study Group Discussion: Salisbury Phenomenon

Whats Salisbury effect?

It's a very interesting phenomenon.

It states that when coronary collaterals develop in the face of myocardial ischemia, they improve the blood supply. However they physically restrict left ventricular dilation and thereby raise LVEDP(LV end diastolic pressure) and reduce LV compliance.
This is because they act like tendrils/scaffold which prevent ventricular dilation.

Nice one!

-VM

Ductus Arteriosus : Review of Key Points

Hi everyone ! Just a short review on Ductus Arteriosus.

- Ductus Arteriosus is basically a communication between the Pulmonary trunk and the Systemic Aorta.
- This communication is between pulmonary trunk and the end of Arch of aorta. Just after the Brachiocephalic trunk , and Left Common carotid and Subclavian have branched off.
- In embryonic life this communication helps transport blood from RV- Pulmonary artery to the Systemic circulation.

So ,
Remember :
Prostaglandins Persist

-Prostaglandins, especially PGE1 , act on the Ductal muscle tissue and keep it Open.
-So the Ductus arteriosus stays open.

-This is important in certain Duct dependent lesions
- Duct dependent heart lesions are those which need the presence of an Open ductus to receive blood in systemic / Pulmonary circulation.

- For example -->
✓ Duct dependent lesions for Systemic Circulation are those that cause obstruction to the Left side heart to pump blood into the aorta. These include :

- Coarctation of Aorta ( especially pre Ductal ) : Here there is a constriction of the aorta just before the ductus Arteriosus. So , a persistent Ductus would transport blood from pulmonary circulation into the systemic. 
If ductus gets closed , there would be minimal blood flow to the Lower limbs and abdomen.

- Critical Aortic stenosis.
- Left side Hypoplastic heart.

~~~~~~~~~~~~~~~~~~~~~~~~~

✓ Duct dependent lesions for pulmonary circulation
-These are lesions where pulmonary blood flow would be severely reduced due to some RV- Outflow tract Abnormality and the only source to the lungs would be through the ductus shunting some blood from aorta into the pulmonary vein.

- These include : 

- Critical Pulmonary Stenosis
- Hypoplastic Right heart syndrome
- Tetrology of Fallot
- Tricuspid Atresia
- Ebstein Anomaly

Another important disease is Transposition of the great vessels where this sort of corrects the defect.
~~~~~~~~~~~~~~~~~~~~~~~~~

So. We've seen in what conditions we'd like to keep the Ductus Arteriosus open / persistent.
Normally this Ductus closes functionally within 24 hours of birth. And anatomically between 10 and 14 days post natally.

If this persists on its own for a long time it causes a Congenital Heart Disease called Patent Ductus Arteriosus.
This defect is characterised by shunting of blood into the pulmonary trunk constantly during systole and diastole causing a Continuous murmur.

To close this ductus , we could try using Indomethacin / Ibuprofen especially in preterm children.
These drugs inhibit Prostaglandin synthesis , thus causing Ductus Smooth muscle to constrict and eventually close.

So that's all about the ductus !

Happy studying !
And Stay Awesome !

~ A.P.Burkholderia

Jaundice Syndromes : Mnemonic

Hey everyone. Just a short post on how to remember the Jaundice Syndromes.

So.

Remember :
CGI
(As in the CGI special effects in movies.)

C - Criggler Najjar Syndrome
G - Gilbert Syndrome
I  - Indirect Jaundice ( Unconjugated Bilirubin).

So this would make Dublin Johnson and Rotor Syndromes Direct Jaundice.

Another useful fact :
All are inherited as Autosomal recessive trait except Gilbert and Criggler Najjar 1.

Hope this helped !
Happy studying.
~ A.P.Burkholderia

Lowe syndrome mnemonic

Lowe Syndrome (Oculocerebrorenal dystrophy) mnemonic

Think of Lowe = Love and it'll make sense.

Lowe makes you blind (cataracts, glaucoma)

Lowe makes you HAPpy (High Alkaline Phosphatase along with normal calcium, low phosphate)

Lowe messes with your head (intellectual disability)

LoveR - Renal defects (proximal tubular acidosis, aminoaciduria, and low-molecular-weight proteinuria)

Lowes syndrome is a cause of Fanconi syndrome.

That's all!

-IkaN

Renal Cell Carcinoma Etiology : Summary

Hi everyone. Here's a short summary of the causes for Renal cell carcinoma !

Renal Cell Carcinoma ( or RCC) is a common tumor of the kidneys and is essentially an Adenocarcinoma.
It's quite often called as the 'great mimic' as it is relatively hard to diagnose.

Here's the list of causes of this tumor.

Remember :
CCCC or C4

C = Cigarette smoking and Tobacco usage.
C = Chronic Kidney Disease / Cystic (Acquired) Disease of kidneys.
C = Cadmium, Asbestos and other occupational Exposures.
C = Cancer Syndromes.
Important Cancer Syndromes =

- Von Hippel Lindau Syndrome :
3p mutation in VHL Gene which is a tumor suppressor --> Tumors seen include Cerebellar and Retinal Hemangioblastomas , Pheochromocytoma, RCC (Clear type) and various other Cystic tumors.

- Tuberous Sclerosis

- Birt Hogg Dube Syndrome : Associated with various weird skin changes and chromophobe type RCC.
Skin changes include --> Tumors of Hair disc (Tricho-discoma) , Tumors of Hair follicle - Fibrofolliculoma and Acrochordons ( skin tags).

- Hereditary Papillary Cancer : Associated with MET Gene mutations

- Hereditary Leiomyomatosis with RCC : Associated with multiple Fibroids in the uterus.

That's​ all for today!
Hope this helped.
Happy Studying !
And, as always , Stay awesome !

~ A.P.Burkholderia

Step 2 CK: Differentiating ileus from SBO

Hello! Short post.

SBO: Small bowel obstruction.

Both: Nausea, vomiting, abdominal distension

Ileus: Hypoactive bowel sounds
Dull and constant pain
Dilated bowel but no air fluid levels

SBO: Initially hyperactive, later hypoactive
Colicky abdominal pain
Air fluid levels seen

That's all!
Back to studying.
-IkaN

Neuroblastoma mnemonic

Hello!

The term neuroblastoma is commonly used to refer to a spectrum of neuroblastic tumors (including neuroblastomas, ganglioneuroblastomas, and ganglioneuromas) that arise from primitive sympathetic ganglion cells and, like paragangliomas and pheochromocytomas, have the capacity to synthesize and secrete catecholamines.

Remember the N myc mnemonic for neuroblastoma :

N - Neuroblastoma, N myc gene
M - Crosses midline (differentiates from Wilms)
MY - MYoclonus (Opoclonus myoclonus)
C - Calcifications in tumor present
C - Catecholamine secretion

You can also remember "High BP" for additional findings seen in neuroblastoma:

Horner syndrome
Heterochromia iridis (different colors of the iris or portions of the iris)
Hypertension
Homovanillic acid and vanillylmandelic acid elevated in urine
Bombesin positive
Back pain
Bone pain
Beckwith-wiedemann syndrome association
Posterior mediastinum or retroPeritoneal mass
Pseudorosette
Purple skin lesions
Proptosis
Periorbital ecchymoses

That's all!
-IkaN