Nervous system Flashcards
General considerations
Is it necessary to use life-saving methods
Is it a nervous system problem or is it a kindey/ liver problem
Is it cerebral, spinal or a peripheral dysfunction
Acute or chronic
Infectious disease? herpes type 1, rabies, WNV
Types of neurological diagnosis
Functional or symptomatic
Anatomical
Pathological
Aetiological
The importance of history
Because of the limitations of the examination
Characteristic of neuropathies e.g epilepsy the clinical signs are not always present– put in cameras
Missing subjective info
Infectious diseases! vaccines and epidemics
The disturbing factors that could change the horses behaviour and therefore the clinical signs
Restraints
Sedatives
Environment
Methods of physical exam
Inspection Palpation Postural reactions Vertebral reflexes Cranial nerves Sensitivity Pain perception: supf vs deep
Ancillary diagnostic methods
Neuroradiography Nuclear scintigraphy Computed tomography MRI Electroencephalography Lab tests
Neuroradiography
Plain
Myelography- compression of SC
Angiography- bvs both cerebral and vertebral
Lab tests
Blood is NB to see if another organ system is involved
Urine
CSF!!! NB can do cultures and PCR
Structure of the physical exam
Head!! always start here and check: Behaviour Mental status Head posture and coordination Cranial nerves
Gait and posture Neck and forelimbs Trunk and hindlimbs Tail and anus Cerebrum Brain stem Cerebellum SC Peripheral nerves and the muscles they supply
Lesion at C1-C5
Tetraparesis and neck pain
Normal-exaggerated spinal reflexes
Lesion at C6-T2
Tetraparesis and neck pain
Decreased/absent thoracic limb spinal reflexes
Normal-exaggerated spinal cord reflexes on the pelvic limbs
Lesion at T3-L3
Paraparesis and back pain
Normal thoracic limb spinal reflexes
Normal- exaggerated pelvic limb spinal reflexes
Lesion at L4-S3
Paraparesis and lower back pain
Normal thoracic limb spinal reflexes
Decreased/absent spinal reflexes on the pelvic limbs
Caudal lesions
Paresis of tail
Decreased tail tone
Decreased tail sensation
Localisation of lesions
Use the foramen magnum as a gauge
Anything cranially will be a brain issue
Assume central lesion and look at clinical sign, check if they are explicable with lesions in front of the FM.. if not, go one level caudally and try again until you can explain the signs.
What can cranial nerve signs be an indication of?
Cerebral, cerebellar or brainstem disease
Cerebral disease
Seizures
Blindness
Dementia
Mild ataxia or weakness
Cerebellar disease
Hypermetria
Intention
Tremors
Weakness
Brainstem disease
Gait deficits
Altered consciousness
Tetraparesis
Head posture and coordination
Movements at the antlantooccipital joint
Control of the cerebrum, cerebellum and vestibular system
Head posture and coordination: vestibular lesion
Head tilt
Head posture and coordination: cerebral lesion
Deviation toward the side of the lesion
Head and neck are not in the body axis so there is circling
Head posture and coordination: cerebellar lesion
jerky movements during voluntary movements and fine tremor when at rest
What does a left head tilt usually indicate?
skull injury
Cranial nerves
Olfactory Optic Oculomotor Trigeminal Facial Vestibulocochlear Glossopharyngeal, vagus and acc Hypoglossal
Olfactory
use food to examine
Optic
Menace: rapidly approaching- should blink
Test for vision: different obstacles
Oculomotor
Pupillary light reflex
Simple: light in one eye and see how same pupil reacts
Consensual: light in one eye and check the pupil of the other eye, the nerve crossing the optic chiasm– anisocoria if different pupil sizes
Disturbances of the oculomotor nerve
Strabismus: abnormal position of the eyeball
Nystagmus: abnormal movement of the eye can be physio during movement of the head and superficial anaesthesia
Horner's syndrome: Damage of sympathetic nerves miosis ptosis (hanging upper lid) enophthalmos Localized sweating in the cervical area
What is the normal position of the eye
line btw medial and lateral canthus to angle of the pupil
Trigeminal nerve
Facial cutaneous sensation- stick fingers into nares
Palpebral reflex- the sensory component- touch upper eyelid
Corneal reflex- sensory- use cotton to touch
Chewing and movements of the jaw
Facial nerve
Facial symmetry and movement so paralysis is easy to see
Palpebral and corneal reflexes- the motor activity
Vestibulocochlear nerve
hearing and balance
Vagus group (glossopharyngeal, vagus and acc)
Swallowing reflex
Thoraco-laryngeal adductor test= slap test to diagnose laryngeal nerve paralysis
Slap withers on one side and then palpate larynx on the opposite side, more common left-sided paralysis
Hypoglossal nerve
Tongue function
Ataxia
lack of coordination
graded from 1-5, 5 being lateral recumbency
Dysmetria
hypo or hypermetria due to abnormal range or force of motion
Hypometria
voluntary movement shorter than intended goal
too little joint movement
dragging of hooves
Hypermetria
voluntary movements overreaching the intended goal
excessive joint movement
e.g WNV encephalitis with held-up tail
Paresis
muscle weakness resulting from neurologic dysfunction
Paralysis
cannot move voluntarily
Evaluation of the neck and forelimbs
- With food
- Cervicoauricular reflex- tap neck at C2 and ear on the same side moves
- Cervical cutaneous sensation- hemostat
- Deep pain perception- press coronary band- not reliable
- Sway reaction- lateral pressure on withers
- Dorsal pressure on withers- stability and balance
- Postural reactions/ Correction tests:
crossing limbs
put legs into wider stance
sideways hopping if safe! lift up one leg
Evaluation of the trunk and hind limbs
similar to forelimb!
Sway reaction- push tuber coxae laterally, if doing it while walking pull the tail
pressure on the lumbar region
Recumbent horses: forelimb tests
flexor reflex: thermostat pinching
biceps reflex: hammer in front of shoulder joint
Triceps reflex: just above olecranon
Recumbent horses: hindlimb flexors reflexes
Tibial- plantar aspect of the metatarsus
Peroneal- dorsal part of tarsus and metatarsus
Femoral- medial thigh
Patellar: lift leg a bit and tap on the ligament
Recumbent: ability to lift head, neck and limbs used for localization of the lesion
Can only lift head: cranial cervical region
Head and neck: caudal cervical region
‘Dog-sitting’- lesion in cervical cord
Functional thoracic limbs- caudal to T2
Deficit in trunk/hindlimbs- between T2 and S2
Localised sweating- desc symp tracts
