Neuromuscular Disease

Question 1

Describe the 3 components of a motor unit

Answer 1

1. LMN
2. NMJ
3. Muscle effector

• Disease affecting any part of this functional unit = neuromuscular disease

Question 2

3 Types of Neuromuscular Disease

Answer 2

• Neuropathy
• Junctionopathy
• Myopathy

​these will often have a similar clinical manifestation –> neuromuscular manifestation

Question 3

dysphonia

Answer 3

difficulty in speaking due to a physical disorder of the mouth, tongue, throat, or vocal cords

Question 4

Myalgia

Answer 4

pain in a muscle or group of muscles

Question 5

Tetraparesis

Answer 5

Tetraparesis, or quadraparesis, is a condition in which all four limbs are weak

Question 6

Why do we see Cervical Ventroflexion in cats with weakness, but not dogs?

Answer 6

due to the passive support provided by the nuchal ligament

• this is not present in cats
• runs from T1 dorsal spinal process and inserts on C2 dorsal spinal process
• dog doesnt have to have inititated muscle contraction to keep their head up as they have passive support

Question 7

Eclampsia

Answer 7

• Eclampsia (hypocalcemia or puerperal tetany) is an emergency medical condition associated with a life-threatening drop in blood calcium levels that occurs in nursing mothers.
• Eclampsia most commonly occurs when the puppies are one to four weeks of age and the mother is producing the most milk

Question 8

Name the Main 8 Parts of a Neuro Exam

(what parts would expect to see abnormalities in an NMD patient?)

Answer 8

1. Mentation
2. Gait
3. Posture
4. Postural Reactions
5. Spinal Reflexes
6. Cranial Nerves
7. Palpation
8. +/- Nociception

• NMD patients will have most of these affected most likely besides mentation (brain stem isnt involved) and Nociception (predominantly talking about LMN, NMJ to muscle so we are going to affect sensation)

Question 9

what is an exapmle of a case where you would see ataxia without weakness?

Answer 9

cerebellar disease

Question 10

Spinal reflex deficit in Investigation of NMJ would indicate which localization?

Answer 10

• Neuropathy

Question 11

on PE we find we have reduced reflexes in both the front legs and back legs (LMN signs)

Answer 11

• would make us think about this being a generalised neuropathy or generalised neuromuscular condition
• if we have the CN’s involved as well, this makes us think about disease processes we know that involve the CN’s

Question 12

plantigrade/palmigrade stance in cat, muscle tone loss, muscle atrophy signs

what type of NMD would you be thinking of?

Answer 12

make you think neuropathy compared to the other two groups

Question 13

Spinal refelxes dampened but relatively intact, but marked exercise intolerance (5 min out of the cage becomes very weak)

what type of NMD would you be thinking of?

Answer 13

• junctionopathy
• spinal relflexes are not particularly decreased but there is marked exercise intolerance —> might think junctionopathy (animals that look relatively normal until you start to exercise them, animals that become very weak with just a bit of exercise) - primarily an exercise intolerance

Question 14

Polymyositis

Answer 14

• Polymyositis is one of the inflammatory myopathies, a group of muscle diseases that involves inflammation of the muscles or associated tissues, such as the blood vessels that supply the muscles.
• A myopathy is a muscle disease, and inflammation is response to cell damage.

Question 15

Muscular Dystrophy

Answer 15

• Muscular dystrophy (MD) is a group of musclediseases that results in increasing weakening and breakdown of skeletal muscles over time.
• The disorders differ in which muscles are primarily affected, the degree of weakness, how fast they worsen, and when symptoms begin

Question 16

Electromyography (EMG)

(first part of electrodiagnostic tests)

Answer 16

• Electromyography measures the electrical discharges produced in muscles.
• During the test, two thin needle electrodes are placed in different regions of the body and a third is placed in the muscle to be studied.
• An instrument records the electrical activity in the muscle at rest and as the muscle is stimulated to contract.
• The size, duration and frequency of these signals helps determine if there is damage to the muscle or to the nerves leading to the muscle.
• Ideally, an electromyography study is performed on an awake patient since the muscles communicate best when the muscle cells are “warm.”

Question 17

What would an EMG reading like this tell us?

Answer 17

• That the NMD is likely a myopathy or a Neuropathy
• this rules out junctionopathy
• this can help out map out the disease as well because you can then figure out WHICH muscles are affected

Question 18

Nerve Conduction Velocity (NCV) Studies

(Part 2 of Electrodiagnostics)

Answer 18

• once you have come down to it being a Myopathy or Neuropathy after EMG
• Nerve conduction velocity studies are performed by placing thin needle electrodes on the skin over particular nerves and the muscles that are innervated by those nerves. Electrical stimulation is applied to activate the nerve and see how it functions as the signal is sent along the nerve. An instrument records the velocity of the signal traveling along the nerve. This test is often performed after an EMG and is good for evaluating neuropathies caused by demyelination or axonal degeneration. Repetitive nerve stimulation may also lead to reduction of evoked potential as seen in myasthenia gravis

Question 19

if the EMG was abnormal, but the nerve stimulation was normal on NCS

Answer 19

• Tells us that we most likely have a muscle disease (myopathy)

Question 20

If both the EMG are abnormal and the NCS nerve stimulation are abnormal

Answer 20

• tells us that we have nerve disease (neuropathy)

Question 21

Myasthenia Gravis

Answer 21

• Myasthenia gravis is a chronic autoimmune neuromuscular disease that causes weakness in the skeletal muscles, which are responsible for breathing and moving parts of the body, including the arms and legs
• The hallmark of myasthenia gravis is muscle weakness that worsens after periods of activity and improves after periods of rest. Certain muscles such as those that control eye and eyelid movement, facial expression, chewing, talking, and swallowing are often (but not always) involved in the disorder.
• The muscles that control breathing and neck and limb movements may also be affected.

Question 22

DAMNITV System of Differentials in Neurology

Answer 22

Question 23

Good diagnostic test if you suspect Myasthenia Gravis

Answer 23

Question 24

Tetraplegia

Answer 24

• also known as quadriplegia, is paralysis caused by illness or injury that results in the partial or total loss of use of all four limbs and torso;
• paraplegia is similar but does not affect the forelimbs
• The loss is usually sensory and motor, which means that both sensation and control are lost
• ABSENCE OF VOLUNTARY MOVEMENT

Question 25

Should Proprioception be affected by a purely neuromuscular (LMN) Disease?

Answer 25

NO.

Question 26

acute canine polyradiculoneuritis

Answer 26

• Acute canine idiopathic polyradiculoneuritis (ACIP) is a creeping paralysis due to acute inflammation of the nerves.
• This disease is often seen in dogs that live in North America as well as in those areas where raccoons are present but overall incidence is quite low.
• Any breed is at risk, but dogs that regularly come into contact with raccoons are at increased risk, such as hunting dogs and dogs that live in rural or wooded areas.
• TOP DX: in any dog that is more a neuropathy case, acute onset, progressive, symmetrical, not necessarily painful

Question 27

Diabetic Neuropathy

Answer 27

• Diabetic neuropathy, which is more common in cats than in dogs, can develop at any time following a dog’s initial diagnosis of diabetes.
• Its main symptom is progressive weakness or paralysis in a dog’s hind legs, which is caused by excessive levels of glucose in the dog’s blood.
• The high glucose levels damage the sheaths, or coverings, on the nerves in your dog’s body, and the nerves in his hind legs are particularly vulnerable to damage.
• Both legs are affected equally in diabetic neuropathy.

Question 28

Most common acute, progressive, generalised NM weakness seen

Answer 28

acute canine polyradiculoneuritis

Question 29

most common cause of cervical ventroflexion and myopathy in a cat

Answer 29

Hypokalaemia