Intro to Neurology Flashcards
1
Q
What are the Upper Motor Neurons? origin? pathway? function?
A
- Origin: Cerebrum or brainstem
- Pathway: Spinal cord to connect the brain to the lower motor neurons
- Function: synapse with lower motor neurons that innervate muscles
- AKA - “long tracts’
2
Q
What happens when the UPN are damaged?
A
- Increased muscle tone (hypertonus)
- Exaggerated spinal reflexes (hyperreflexia
3
Q
What are the Lower Motor Neurons?
A
- Origin: CNS
- Pathway: exits CNS to form the cranial nerves and peripheral nerves
- LMN for the forelimbs and pelvic limbs arise from the cervical intumescence (C6 - T2, “cervicothoracic spinal cord”) and lumbar intumescence (L4 - S2, “lumbosacral spinal cord”)
- Function: final pathway to innervation and activation of muscular activity
4
Q
What happens when LMN are damaged?
A
- Decreased muscle tone (hypotonus)
- Diminished or absent spinal reflexes (areflexia or hyporeflexia)
5
Q
What is “ipsilateral”
A
- Lesion on the same side of the body as the neurological deficit
6
Q
What is “contralateral”
A
- Lesion on the opposite side of the body as the neurological deficit
7
Q
Why is there “sidedness” in neurologic issues?
A
- A function of decussation - crossing of nerve fibers over midline from one side of the body to the other
8
Q
What is the ascending tracts of the spinal cord? Functions?
A
- Resonsible for proprioception and various forms of sensory input, including pain
- Sensory tracts designated by the prefix “spino-” although the dorsal white column is also sensory
- Proprioception:
- dorsal white column - contralateral cerebrum
- spinocerebellar tracts - ipsilateral cerebellum
- Spinothalamic tracts are involved in pain, temp, and pressure sensation
- Lateral spinothalamic tract - “superficial” pain sensation
- Ventral spinothalamic tract - “deep” pain sensation
9
Q
What are the functions of the Descending Tracts of the Spinal Cord?
A
- Corticospinal tracts - conscious motor control over skeletal muscles
- Vestibulospinal - controls muscles for posture and balance
- Tectospinal - responsible for responses to startling visual or auditory input
- Reticulospinal - activates respiratory muscles
- Rubrospinal - controls flexor and extensor tone
10
Q
When the spinal cord is compressed what senses are lost first? which are regained
A
- When external force is being applied the larger fibers are easier to compress and lose function first.
- Senses lost in this order
- Proprioception is lost first
- Conscious motor
- Superficial pain
- deep pain
- severe spinal cord injury, prognosis for recovery is grave (<5% chance)
- Functions regained in the opposite direction
- In the picture:
- smallest red circle = reticulospinal tract, its size explains why respiratory control is not lost with cervical and thoracic spinal cord lesions and would only happen after deep pain is lost
11
Q
define paralysis
A
- complete loss of function
- suffix “-plegia”
12
Q
define paresis
A
- Muscular weakness associated with neurological dysfunction
13
Q
what prefixes can be used to modify “-plegia” or “-paresis” that describe how the body is affected?
A
- “tetra-“ affecting all 4 limbs
- “Hemi-” affecting the front and rear limbs on one side of the body
- “para-” affecting only the rear limbs
14
Q
What are the goals of an initial neurology examination?
A
- Determine if the patient has neurological disease
- Localize the lesion
- Create a reasonable list of differential diagnoses (broad or specific)
- Determine level of therapeutic intervention prior to a diagnosis
- Select appropriate diagnostics
15
Q
What is a “time course of disease”
A
- Progression of clinical signs in a patient as they move further away from their normal
- A sudden (peracute) change is described as “lights on/lights off”
- Traumatic
- Vascular
- Toxicity
- Idiopathic cause
- Progressive deterioration in a patient’s neurological status is typically caused by infectious disease, immune-mediated disease, neoplasia, and degenerative conditions, although the speed of decline would be different for each of these
16
Q
what is Mental status controlled by? how is it described?
A
- Mental status is under the control of the cerebrum and ascending reticular activating system (RAS)
- Basic descriptors of mental status:
- Alert: implies a normal state of consciousness. “normal” varies due to different behavioral responses to situations
-
Inappropriate: all-inclusive term for abnormal mental function that fits somewhere between normal and stupor/coma
- Depressed: quite and unwilling to perform normally but responds to environmental stimuli
- Obtunded: dull and relatively nonresponsive but conscious
- Demented: unrecoverable loss of higher brain functions
- Delirious: temporary disturbance of higher brain functions characterized by inappropriate responses by behaviors
- Stuporous: unconscious in the presence of normal environmental stimuli, but can be roused with more intense stimuli
- Comatose: unconscious regardless of the intensity of the stimulus applied
17
Q
What gait abnormalities are common with neurological issues? what locations are associated with these abnormalities?
A
- Ataxia - sensory, cerebellar, vestibular
- Hypermetria (dysmetria) - Cerebellum or cerebellar pathways
- Circling - cerebral, cerebellar, vestibular
18
Q
What are the different forms of ataxia? areas of the nervous system are the source?
A
- Ataxia - loss of muscular coordination
- instability when walking
- falling or swaying from side to side
- Crossing limbs when walking
-
Sensory (proprioceptive) Ataxia
- Origins: Peripheral nerves, spinal cord, brainstem, cerebrum
- Visual cues can help with compensation
-
Vestibular Ataxia
- Origins: Peripheral or central vestibular
- Central vestibular disease may have components of sensory and vestibular ataxia
-
Cerebellar ataxia
- can be present without loss of motor function
19
Q
What is proprioception?
A
- Perception or awareness of the position and movement of the body
- Orientation in relation to gravity
- Orientation of a joint (to prevent hyperflexion or hyperextension) or body parts in relation to each other
- Proprioceptive deficits involve disruption of the sensory pathway from peripheral nerve, through spinal cord, brainstem, midbrain and to central recognition (cerebrum) of perception
- An animal can be ataxic (cerebellar or peripheral vestibular) and still have proprioception, although the ability to place may be affected
20
Q
What are the differences between “big” and “small” circling
A
- “Big” circles:
- Characteristic of cerebral disease
- Generally circle in the direction of where the mass is located
- The patient will overstep with the thoracic limb contralateral (on the opposite side) of the mass
- On occasion dogs may circle in the direction opposite to the side of the mass (confuses localization
- “small” circles:
- Associated with disease of the vestibular system and cerebellum (or cerebellar pathways)
- Other findings
- Head tilt in the direction of the circling
- Nystagmus
- Cranial nerve 7 deficits (peripheral vestibular)
- Multiple cranial nerve deficits and limb deficits (central vestibular disease)
21
Q
What is a head tilt?
A
- Abnormal posture of the head in which one ear is held ventral (lower) than the opposite ear
- The nose continues to point straight ahead
- Most often caused by disease of the vestibular or cerebellar systems
- The tilt (down) is generally towards the lesion
- In paradoxical vestibular syndrome, the head tilt is in the direction opposite the lesion (sometimes seen with disease of the cerebellum)
22
Q
What is a head turn?
A
- Abnormal posture in which the plane of the ears remains parallel to the ground
- The nose is deviated toward the caudal aspect of the body
- Most often associated with a cerebral lesion
- Head turn is usually toward the side of the lesion
- Circling may also be associated with the head turn
- In some patients with caudal brainstem lesions a component of head turn and head tilt can be seen
23
Q
How is Conscious proprioception evaluated?
A
- Technique:
- Place the paw where a footfall would land with the dorsal surface of the paw on the ground
- Support the pet’s weight (hand under the pelvis or cheat)
- If the patient fails to replace the paw in the appropriate position, there is no need to perform additional tests to evaluate proprioception
- If the pet has an ataxic gait (or deficits are suspected) but the patient rapidly returns the paw to the appropriate position, then additional tests are performed to detect more subtle deficits in proprioception
- Tips:
- Severe pain may produce pseudo-deficits
- Brusque or excessive movement ⇒ additional pain/pressure and proprioceptors may be fired, making subtle abnormalities difficult to identify
- Cats don’t participate in this postural reaction
24
Q
What is the hopping test?
A
- Technique:
- Slightly lift the leg opposite to the one being examined
- Use this hold to push the dog toward the limb to be examined
- As the paw goes toward midline the patient will hop the limb laterally to maintain balance
- Pivot point are the paired limbs- not examined
- Paper slide test (modified hopping)
25
Q
What is the Wheelbarrowing Test?
A
- Technique:
- performed by lifting the pelvic limbs off the ground and walking the patient forward
- The head can be elevated (and eyes covered) to remove visual cues and detect subtle deficits
- Cats aren’t fans
26
Q
What is the Hemiwalking Test?
A
- Techniques:
- Performed by lifting the limbs (fore and rear) on one side of the body and pushing the dog towards the other limbs
- The limbs will correct to keep the patient from losing balance and falling
- Cats don’t like
27
Q
What is the test for the Extensor Postural Reaction?
A
- Technique:
- Performed by holding the patient vertically and bringing them down to land on the pelvic limbs
- The patient will naturally step back so that they can land on their front feet
28
Q
What is the Tabletop placing test/
A
- Technique:
- Performed by holding the patient and brining their feet to the table top, individually or in pairs
- Avoid “deceleration reaching”
- Covering the eyes is important to remove visual cues
- One of the better tests for cats and small dogs
31
Q
What is the Quadriceps reflex?
A
- “Patellar Reflex”
- Most reliable reflex to interpret in dogs and cats
- Evaluates the L4-L6 spinal cord segment and the femoral nerve
- If patient is tense ⇢ reflex may be difficult to elicit
- The expected response is extension of the stifle
- Technique:
- Place a hand under the paw and flex and extend the leg to relax the pet prior to trying to elicit the reflex
- Another method is to gently support the leg and tap the patella tendon
- Evaluating the patellar reflex on the dependent leg (down leg)
- Less reliable in older dogs and dogs with severe, chronic stifle disease (DJD or Cruciate rupture)
33
Q
What is the cranial tibial reflex?
A
- Evaluates the L6-L7 spinal cord segment and the peroneal branch of the sciatic nerve
- The expected response is flexion of the hock
- Technique:
- The proximal aspect of the muscle belly is percussed
34
Q
What is the gastocnemius reflex?
A
- Evaluates the L7-S1 spinal cord segment and the tibial branch of the sciatic nerve
- 2 Techniques:
- Percuss the insertion of the tendon and look for extension of the hock
- Flex the hock to tense the tendon prior to percussion of the distal tendon and look for contraction of the gastrocnemius muscle
35
Q
What are the Flexor (‘withdrawal’) responses?
A
- Evaluates the sensory component, reflex arc, and motor component (w/ some contribution of voluntary flexion)
- Often dependent on the force applied and the nature of the patient (for the voluntary component
- The interpretation of this reflex is questionable at best
- A flexion response requires NO input from above and should be lost with a LMN lesion and present with an UMN lesion
- This does not require higher input and is often misinterpreted as the central recognition of pain
36
Q
What is the Biceps reflex?
A
- Evaluates the C6-C8 spinal cord segment and the musculocutaneous nerve
- Technique:
- Index finger is wrapped around the distal insertion of the biceps tendon
- Elbow is pulled slightly caudally to stretch the tendon
- The finger is tapped with the pleximeter (reflex hammer) and the examiner watches for contraction of the biceps muscle
- All forelimb reflexes are a bit difficult to elicit and interpret - you may be wrong
37
Q
What is the Triceps reflex?
A
- Evaluates the C7-T1 spinal cord segment and the radial nerve
- Technique:
- hold the forearm and pull the elbow slightly caudally and rotate the elbow outwardly to stretch the triceps tendon
- Percuss the tendon and examine for contraction of the triceps
- The index finger can also wrap around the triceps tendon to tension it further and the finger tapped with the pleximeter
- Alternate method:
- Tap the triceps tendon or muscle belly and look for extension of the elbow, although paradoxically this will sometimes elicit flexion of the elbow
38
Q
What is the Extensor carpi radialis reflex?
A
- Evaluates the C7-T1 spinal cord segment and the radial nerve
- Technique
- Percuss the proximal muscle belly of the extensor carpi radialis muscle
- Extension of the carpus. Limb is supported passively to elicit this reflex
39
Q
What is the Babinski reflex?
A
- Has no real bearing on the exam
- Normally absent in the neurologically intact patient
- Plantar or palmar surface of the paw is stroked in a proximal to distal direction
- Normal - Nothing or slight flexion of the foot and splaying of the toes
- UMN lesion to the limb - extension of the foot and splaying of the toes
44
Q
What is the Pupillary light reflex?
A
- Sensory Pathway: Optic nerve (CN2)
- Motor pathway: Parasympathetic nerve as a component of the oculomotor nerve (CN 3)
- Perform in dark room with very bright light
- PLR can be absent due to disease of the cornea, iris (iris atrophy), lens, anterior or posterior chamber, retina, optic nerve, midbrain, and oculomotor nerve pathway
- Evaluate direct and consensual responses to localize the lesion
53
Q
How is the Menace Response tested?
A
- Tests:
- Sensory pathway - CN2
- Motor pathway - CN 7
- When threatened or presened with somethin that suddenly appears close to the eyes/face, the patient will blink
- If create a breeze with the hand ⇢ sensory pathway of the cornea (CN5) can be elicited
- Generally easy to evaluate (absent in some cats and fairly young puppies and kittens)
- Patients with cerebellar disease may have an intact CN2 and CN7 and still not have a menace response
