Bovine neurology: Lesion localization, neurologic exam, and why we care (Proceedings)

Question 1: Is it a primary neurological disease?

Question 2: Is it rostral or caudal to foramen magnum?

Etiologies

A. bacterial

B. viral

C. toxic

D. metabolic/nutritional

E. traumatic

F. neoplastic

G. congenital or hereditary

H. degenerative

History

A. Very important!

B. Environment ie: hogs nearby?, junkyard?, plants?, feeding practices?, silage?

C. Past disease? ie: pneumonia?, diarrhea?, navel infection?, BVD?

D. Age of onset

E. Breed ie: Brown Swiss, Charolais, Saler

F. Length of illness

G. Therapy and response

H. Past vaccinations, dehorning, castrations, spraying

Signs associated with lesions in the head

Cerebrum

Diffuse or Local

A. Seizures

B. Depression –Reticular Activating System

C. Change in mentation

D. Cortical blindness (normal PLR)

E. Compulsive circling

F. Opisthotonus

G. Head pressing

H. Yawning

I. Bellowing (abnormal vocalization)

Cerebellum

A. Ataxia w/o paresis

B. Intention tremors

C. Wide based stance

D. Hypermetria

E. Strong muscle tone

F. Falling over backwards

G. No conscious proprioception (CP) deficits

H. May lack menace reflex, but have normal vision (swelling in the cerebellar region

Vestibular

Peripheral – usually not depressed (ie: Pasteurella, Histophilus., Mycoplasma, ear ticks/mites

A. Head tilt – to side of lesion

B. Eye drop- to side of lesion

C. Leaning- to side of lesion

D. Circling – to side of lesion

E. Nystagmus – fast phase away from lesion – usually horizontal

F. Ataxia w/o weakness

G. Bright, alert, good appetite

Central – depression can occur

A. Head tilt

B. Eye drop

C. Circling

D. Hemiparesis

E. Nystagmus – horizontal/vertical/rotary - fast phase any direction (changes direction with movement of head)

F. Ataxia w/weakness

G. Llose appetite

H. Change in mentation

Thalmus/Hypothalmus

A. Change in behavior

B. Temperature regulation difficulties

C. Heatstroke?

D. Endocrine dysfunction

Brain Stem

General: ataxia and paresis, depression to mania

pons and medulla – depression and irregular respiratory movements

Most cranial nerve deficits are due to disease in the brain stem on cranial n. nuclei (ie: listeria, TEME)

Cranial nerves, signs of deficit and (sensory or motor designation)

1. Olfactory – can't smell smoke (Sensory)

2. Optic – loss of vision (Sensory)

3. Oculomotor – pupil dilation, ventrolateral strabismus (Motor)

4. Trochlear – dorsomedial strabismus (Motor) ie: polio

5. Trigeminal – loss of sensation to head/tongue (Sensory), dropped jaw due to loss of muscles of mastication, atrophy (Motor)

6. Abducens – medial strabismus, protrusion of eye (Motor)

7. Facial – loss of motor to the head (Motor), loss of sensation to tongue (taste) (Sensory) – otitis interna/media

8. Vestibulo-Cochlear – loss of hearing, loss of equilibrium (Sensory)

9. Glossopharyngeal – loss of motor to the muscles of pharynx (Motor), loss of sensation of pharynx, loss of parotid and zygomatic salivary glands (Sensory)

10. Vagus – loss of motor to pharynx, GI tract, heart, lungs, larynx (Motor), loss of sensation to pharynx, larynx, esophagus, trachea, part of external ear (Sensory), loss of afferent limb of many visceral reflexes

11. Accessory – loss of motor to trapezius, sternocephalicus, brachiocephalicus, larynx, pharynx (Motor)

12. Hypoglossal – loss of motor to muscles of tongue (Motor)

Signs associated with lesions in the spinal cord

Focal: general causes

A. Vertebral trauma

B. Vertebral body abscess

C. Vertebral fractures – ie: spondylosis in old bulls, malnutrition in young (Cu deficiency, high P/low Ca

D. Lymphoma

E. Congenital malformation

Multifocal:

A. CAEV – young goats

B. Parelaphostrongylus tenuis – sheep, goats, llamas

C. Hypoderma bovis

Diffuse:

A. Rabies

B. Pseudorabies

C. O-P toxicity

D. Botulism, tetanus

E. Copper toxicity

F. Progressive ataxia –Charolais and Brown Swiss (spinal muscle atrophy)

Gait deficits

A. Paresis – flexor weakness – brain stem white matter or spinal cord

a. Extensor weakness – spinal cord gray matter

b. Limb dragging

c. Worn hooves

d. Buckling

e. No ataxia

f. Trembling when bearing weight

B. Ataxia

a. In coordination

b. Swaying

c. Abducted or adducted limb placement

d. Limb crossing

e. Pivots on inside limb and circumducts outside limb when circling

C. Dysmetria

a. Hypermetria

b. Hypometria

Reflexes

Panniculus reflex – cutaneous trunci (C8, T1)

hyperesthesia – cranial to lesion

anesthesia – at and caudal to lesion

Crossed extensor reflex – not normal except in young calves – lesion above reflex arc

Flexor reflex, Triceps reflex, Patellar reflex

Lesion localization:

C1-C6 – Altered head and neck movements

Superficial sensation loss

CP deficits

Increased reflexes

Ataxia/weakness to all four

Recumbent – lesion side down can lift head, lesion up only lift head if caudal to C4

Truncal sway

Knuckle, stumble, fail to lift inside limb when turning

C6-T2 – Hyperactive rear limb reflexes

Depressed fore limb reflexes

CP deficits- knuckle, stumble

Superficial sensation loss

Ataxia/weakness – forelimb can = rear limb

T2-L3 – Normal fore limb reflexes

Hyperactive rear limb reflexes

CP deficits in hind limbs

Superficial sensation loss

Ataxia/weakness – hind limbs

Dog sit

L4-S2 – Normal fore limb reflexes

Depressed rear limb reflexes

CP deficits in rear

Superficial sensation loss

Ataxia/weakness – hind limbs

S1-S2 – Bladder distention, loss of anal tone

"LMN Bladder" dribbles

S3-Cd5 – Flaccid tail, anus, loss of sensation to penis, vulva, perineum (caudal epidural)

Ancillary Diagnostics

CSF fluid:

Collection

Cisterna magnum – midline just cranial to a line connecting anterior edges of the wings of the atlas

Lumbosacral – midline in the lumbosacral space

Bovine Reference:

Protein: < 40 mg/dl

Nucleated cells: < 10/microliter – monocytes

Pandy: neg. for globulin

Glucose: 60-80% of blood

CPK: < or = 20 IU/dl

Sodium: 134-144 mEq/L

To summarize the above: neurologic examination of the ruminant

Broad view

Is it primary neurologic disease?

History

Gait

Posture

Mentation

Is it rostral or caudal to the foramen magnum?

Rostral to the foramen magnum

Cerebrum

Cerebellum

Vestibular system

Brain stem/cranial nerves

Caudal to the foramen magnum

Spinal cord

Peripheral nerves

Specific view

Overall assessment (from a distance)

Gait – ataxia - focusing on coordination and strength

Posture – ie: head, body, limbs – animals with postural abnormalities may have normal gaits, but animals with abnormal gaits will always have abnormal postural reactions

Mentation – is animal responding appropriately to environmental stimuli?

Does the history or above examination suggest neurologic disease?

Closer examination (hands-on)

Cranial nerve examination:

Ocular exam

Palpebral, menace, papillary light reflex, corneal reflex

Ophthalmoscopic examination

Postural responses:

Proprioception, (adults), placing, hemistanding/walking (young or small ruminants)

Spinal reflexes:

Panniculus, perineal, patellar and withdrawal (flexor)

Palpation:

Localized areas of pain, sweating, atrophy

Peripheral nerves:

Obturator, sciatic, femoral, peroneal, tibial, suprascapular, radial

End result from the above process hopefully is LOCALIZATION.