1.8 Small Animal Neurological Exam Flashcards
List the spinal cord segments and the number of vertebrae in each.
dog and cat:
- Cervical (7)
- Thoracic (13)
- Lumbar (7)
- Sacral (3)
- Variable number of caudal (tail)
What are the functional groups of the spinal cord?
- C1- C5
- C6 - T2: forelimb issue
- T3 - L3
- L4 - S3: hindlimb issue
What are the main groups of neuropathology (localization)?
- encephalopathy (CNS - brain)
- myelopathy (SNC - spinal cord)
- neuropathy (peripheral nerve)
- junctionopathy (NMJ)
- myopathy (muscle)
What is the 5 finger rule for a neurological exam?
- onset (when did it start)
- clincal course (progression, duration, evolution)
- lateralization
- pain
- neuroatomical localization
(the wrist is signalment, because it supports the entire hand - all information should go though the filter of signalment)
What does the hands off neurological exam comprise of?
detailed information to come
- mental status and behavior
- obtunded (conscious but less interest in environment)
- unconscious (stuporous vs comatose)
- abnormal behavior (disoriented, circling, head pressing, hemi-neglect)
- posture and body position at rest
- head tilt
- head turn
- wide base stance
- trunk abnormalities (scoliosis/kyphosis/lordosis)
- limb abnormality (spontaneous knuckling, nerve root signature)
- rigidity (schiff-sherrington)
- gait analysis
- coordinated or uncoordinated (ataxia)
- loss of motor function (paresis vs plegia)
- lame (orthopedic vs neurologic)
What does the hands on neurological exam comprise of?
detailed information to come
- postural reaction testing (requires forebrain)
- knuckling test
- hopping test
- extensor postural thrust
- spinal reflexes, muscle mass, and tone
- withdrawl reflex
- extensor carpi radialis
- patellar reflex
- perianal reflex
- cutaneous trunci reflex
- cranial nerve assessment
- PLR
- menace response
- fixating response
- vestibulo-ocular reflex
- palpebral reflex
- corneal reflex
- facial sensation
- gag reflex
- palpation (areas of pain / discomfort)
- test nociception (deep pain different than superficial sensation of touch)
What do spinal reflexes test?
Spinal reflexes test the integrity of sensory AND motor components of the reflex arc and the influence of descending motor pathways on the reflex
- an absent or depressed reflex indicates complete or partial loss of either the sensory or motor nerves responsible for the reflex (LMN)
- a normal reflex indices that sensory and motor nerves are intact
- an exaggerated reflex indicates an abnormality in the descending pathways from the brain and spinal cord that normally inhibit the reflex (UMN)
in general, forelimb reflexes are not as reliable for localizing lesions as rear limb reflexes
What is the withdrawl reflex?
the most reliable SC localization test: examiner pinches both medial and lateral toes, and the limb should withdraw
- the forelimb tests the musculocutaneous, median, ulnar, radial, and axillary nerves and associated spinal cord segments C6-T2
- the hindlimb tests the sciatic nerve and associated SC segments L4-S1
What is the patellar reflex?
- tapping the patellar tendon
- a positive response is stifle extension
- this reflex assesses the femoral nerve and its associated spinal cord segments L4-L6
What is the extensor carpi radialis (ERC) reflex?
the forelimb version of patellar reflex: tests C7-T2
- performed with the animal in lateral recumbency
- the limb is supported under the radius; the elbow is fully extended and the entire leg drawn caudally
- the ECR tendon is struck with a reflex hammer at its insertion
- normal response is slight extension of the carpus.
What is the perianal reflex?
- touching or pinching the perineal region, with contraction of the anal sphincter seen with a positive response
- lack of an contraction of the anal sphincter may be seen with a spinal cord lesion in the S1-S3 segment or associated nerves
What is the cutaneous trunci reflex?
elicited by pin-prick stimulus to the skin over the back, beginning at the lumbosacral region and continuing cranially
- normal response is twitching of the cutaneous trunci muscle on both sides of the dorsal midline, at the point of stimulation and cranially
- if the response is absent or diminished, the spinal cord lesion is 1-2 vertebrae cranial to this level would be a concern (remember: the sensory nerves travel slightly cranially before synapsing)
What does each CN test examine?
- PLR: CNII → CNIII
- menace response: CNII → CNVII (+ cerebral cortex, cerebellum, rostral colliculi: learned response)
- fixating response: CNII → CNIII + CNIV + CNVI
- vestibulo-ocular reflex: CNVIII → CNIII + CNIV + CNVI (no visual input needed)
- palpebral reflex: CNV → CNVII (orbicularis oculi)
- corneal reflex: CNV → CNVII (closes eye) + CNVI (retracts eye)
- facial sensation: poke nose (decreased sensation occurs contralateral to lesion)
- gag reflex: IX + X
For the eye:
LR6, SO4, O3
Lateral rectus = CNVI
Superior Oblique = CNIV
Others = CNIII
Note CNVI also innervantes the retractor bulbi
What does DAMNITV stand for?
