Exam 6: Neuro Flashcards
Most critical part of clinical neurology
neuroanatomic diagnosis
No conscious proprioception in pelvic limb, no voluntary movement of pelvic limb, but normal patellar and withdrawal reflexes, thoracic limbs normal: which spinal cord segments?
T3 - L3 spinal segments
Acute Spinal Diseases: most common causes
- Trauma (external)
- Neoplasia
- Myelitis/meningitis
- Intervertebral Disk Disease
- Vascular
Don’t forget…
Look where you localize!!!
Things to note when considering neurological abnormalities:
Look for abnormalities of:
- Posture
- Appearance
What is a hyperkeratotic pad (“Hard Pad”) associated with?
Distemper has been associated w/ hyperkeratotic pad
Physiological causes of Muscle Atrophy
- Disuse (takes time, usually bilateral)
- Neurogenic (can be acute; 3-5 days after damage to a nerve)
- Primary myopathic
Paraspinal Muscle Atrophy
Often caused by discospondylitis
asymmetry of face
1) palpebral fissure differences
2) nasal filtrum deviation
(cranial nerve seven-facial nerve controls this)
opisthotinus
spasm of the muscles causing backward arching of the head, neck, and spine, as in severe tetanus, some kinds of meningitis, and strychnine poisoning.
Decerebrate rigidity
1) opisthotinus
2) extensor rigidity
3) stupor or coma
PATHOGNOMONIC for disease in the midbrain
CLINICAL signs suggest location, not specific disease
(cerebellar disease can look like this but they remain conscious since cerebellum doesn’t involve consciousness. They may do extensor movements intermittently.)
Decerebrate rigidity
Pathognomonic for MIDBRAIN LESION
- rare for animals to recover at this point
- could be heartworm thrombosis, Toxoplasma, FIP
Postural abnormalities
extended or flexed!!
Remember: decerebrate rigidity
Is pathognomonic for midbrain lesion!
But remember tetanus can also look like this. You would want to look immediately for a wound.
But remember spinal cord disease may also disrupt balance between flexors and extensors (i.e. cervical disc problem)
Muscle fibrosis ==> contraction
We can see extensor problems with damage to muscle (i.e. femoral fracture causing fibrosis of quadriceps)
Cushing’s disease and heavily muscled?
Being heavily muscled may cause a stiff stilted short and choppy gait, which is an extensor posture and gait. (Cushing’s disease may cause heavy muscling)
Shiff-Sherrington Posture
1) usually occurs with acute lesions in thoracolumbar area (i.e. fracture of T13-L1 area)
2) front limbs extended, pelvic limbs neutral or slightly flexed (not actively)
Extended Postures
1) neurologic disease (usually central)
2) muscle (skeletal?)
(Also consider tetanus)
Gastrocnemius muscle
Extends hock and is innervated by the sciatic nerve
-may see over flexion of the hock when something is wrong with the gastrocnemius muscle or the sciatic nerve (note if flexion is when they put weight on the limb or not weight on the limb)
Problem with gastrocnemius tendon
1) the superficial digital flexor tendon may be allowed to over-tense the toes
- the toes may be knuckled under and you may see over flexion of the hock at weight-bearing
Gastrocnemius tendon rupture
1) superficial digital flexor over-flexes
- causes knuckling of toes
Cranial tibial muscle
1) flexes the hock
2) is innervated by the sciatic nerve
3) it’s not common to get nerve avulsion with this muscle group
Decreased tone in the pelvic limb
1) indicates damage more likely is present in peripheral nerves
2) sciatic nerve arises from L6, L7, S1, and maybe S2
Fibrotic myopathy
PATHOGNOMONIC GAIT (it's like the only one in vet med neuro!) -The hock turns inward at the height of its elevation
1) semimemnranosus, semitendinosus, and sometimes gracilis muscles become fibrotic and prevent normal movement of the limb
2) German shepherds are over-represented with this disease
3) it’s musculoskeletal disease!! It’s not neurologic disease
4) it likely occurred due to damage of the muscle
Flexed limb postures (when on the ground)
1) neurologic disease (peripheral)
2) muscle (skeletal?)
Flexed limb postures
1) most common pathophysiologic cause: PAIN
2) flexed limb postures are traditionally called “nerve root signature”
If the pelvic limb is affected
DO A RECTAL EXAM
-check for masses etc.
Flexed limb postures (non-weightbearing)
1) PAIN-most common pathophysiologic cause, arising from a structure around the leg
2) neurologic?
3) musculoskeletal?
Ataxia
Lack of an axis
Scoliosis
1) posture of the spine: SIDEWAYS curvature of spine
2) often associated with nervous system problem
- often is in innervation problem to paraspinal muscles, which leads to bone problems in the developing adolescent
Syringomyelia
1) a chronic progressive disease in which longitudinal cavities form in the cervical region of the spinal cord. This characteristically results in wasting of the muscles and a loss of sensation
2) the Cavalier King Charles spaniel have this disease very, very commonly-they are the poster child for this disease!!
Kyphosis
refers to an exaggerated rounding of the back
Ventral neck flexion in the
It is associated with a variety of diseases:
1 electrolyte (potassium) abnormalities
2) hyperthyroidism
3) thiamine deficiencies
4) myasthenia gravis
5) organophosphate toxicities (they also often assume a praying position)
6) a number of other causes..
Short and choppy gait
Usually means one of two things:
1) they are painful
2) they have weakness
What is the tragic facial expression often associated with?
HYPOTHYROIDISM
-often due to muscle weakness
Cranial cruciate ligament rupture
May also cause over-flexion of the stifle
lordosis
Is commonly seen, but usually this is a wasting muscle weakness
1) often associated with Cushing’s disease (hyperadrenocorticiscm)
2) not usually associated with pain
Patient keeping their head down?
It usually indicates there’s pain somewhere (dogs with cervical pain often present with a codified posture and thoracic lumbar area)
Flexure posture with no weight-bearing
Often associated with pain
Flexor posture with weight-bearing
Often associated with musculoskeletal issue
Extensor posture
CNS problem and/or fibrosis of muscle