9. Case Examples and Neurolocalizing Outside the Brain

1/16/2026; Dr. Sullivan

Localize the lesion:

12 yr MN Wire Dachshund: Trouble eating

• mentation: dull

• tetraparesis & ataxia x4

• postural reaction deficits x4

• decreased gas reflex

(go through each bullet point and localize, then establish the overall lesion localization)

• mentation: dull = forebrain or brainstem

• tetraparesis & ataxia x4 = brainstem or spinal cord

• postural reaction deficits x4 = forebrain, brainstem, spinal cord

• decreased gas reflex = brainstem

overall = brainstem

Localize the lesion:

6 yr FS Frenchie: Right head tilt

• circling to R, Ataxia

• R head tilt

• Nystagmus, fp to L

(go through each bullet point and localize, then establish the overall lesion localization)

• circling to R, Ataxia = forebrain or vestibular

• R head tilt = R vestibular- central or peripheral

• Nystagmus, fp to L = R vestibular - central or peripheral

overall = Right Vestibular (not enough to know central or peripheral)

Localize the lesion:

2 yr Siamese Cat: Head pressing

• head pressing

without even examining the cat, where is this neurolocalization?

• head pressing = forebrain

overall = forebrain

The spinal cord is a conduit for:

• Descending _____ (sensory/motor) information

• Ascending ______ (sensory/motor) information

motor; sensory

describe the clinical presentation of the bladder with a patient with UMN signs

-this is commonly seen with lesions located where?

increased tone, difficult to express (seen with lesions cranial to L4)

describe the clinical presentation of the bladder with a patient with LMN signs

-this is commonly seen with lesions located where?

decreased tone, dribbling urine, easy to express (seen with lesions caudal to L3)

describe the response seen in a reflex arc

just read this one good time

what type of signs (UMN/LMN) would you expect to see with a lesion in the C1-C5 region

Upper motor neuron (UMN) signs, such as increased tone and hyperreflexia (reflexes would be intact)

what type of signs (UMN/LMN) would you expect to see with a lesion in the C6-T2 region?

LMN in thoracic limbs (decreased tone, decreased reflexes)

UMN in pelvic limbs (increased tone, intact reflexes)

what type of signs (UMN/LMN) would you expect to see with a lesion in the T3-L3 region?

UMN in pelvic limbs (increased tone in PL, intact reflexes in PL, UMN bladder)

what type of signs (UMN/LMN) would you expect to see with a lesion in the L4-S3 region?

LMN to PL (decreased tone in PL, decreased reflexes in PL, LMN bladder, fecal incontinence)

just read this!!

Reflex: Patellar

Stimulus: Tap patella tendon

Response: Extension of stifle

Localization: lack of patellar reflex localizes specifically to ______

lack of patellar reflex localizes specifically to L4-L6

Reflex: Pelvic limb withdrawal

Stimulus: Pinch skin of toe

Response: Flexion of hock and stifle

Localization: lack of pelvic limb withdrawal localizes specifically to ________

L6-S1

Reflex: Perineal

Stimulus: Touch skin of perineum

Response: Contraction of anus, downward movement of tail

Localization: Lack of a perineal reflex localized specifically to ________

S1-S3

Reflex: Thoracic limb withdrawal

Stimulus: Pinch skin of toe

Response: Flexion of carpus, elbow, and shoulder

Localization: Lack of a thoracic limb withdrawal localizes specifically to _____

C6-T2

Reflex: Cutaneous trunci

Stimulus: Start at level L3 vertebra, pinch skin over trunk, move cranially, testing from L3-T3

Response: bilateral skin twitch

Localization: Lack of a cutaneous trunci reflex localizes to _____

if no twitch caudal to “X” vertebra = lesion just cranial to “X”

if no twitch on one side ipsilateral C8-T1 nerve roots or lateral thoracic nerve.

look over this, but do not expect this to be tested

can the cutaneous trunci reflex be used to localize to the brachial plexus?

yes!

Dark Blue

-fill in the findings #1-5

Orange

-fill in the findings #1-5

Purple

-fill in the findings #1-5

Pink

-fill in the findings #1-5

Localize the lesion:

3 yr MN Hound Mix: Can’t walk in hind limbs

• Nonambulatory paraparesis

• Postural reaction deficits in PL

• Normal spinal reflexes

(go through each bullet point and localize, then establish the overall lesion localization)

• Nonambulatory paraparesis = T3-L3 or L4-S3

• Postural reaction deficits in PL = T3-L3 or L4-S3

• Normal spinal reflexes = T3-L3
  -overall localization = T3-L3 spinal cord segments

Localize the lesion:

7 yr FS DSH: Dragging R hind leg

• Paraparesis, worse R

• Postural reaction deficits R

• Decreased withdrawal reflex R pelvic limb

(go through each bullet point and localize, then establish the overall lesion localization)

• Paraparesis, worse R = Right T3-L3 or L4-S3

• Postural reaction deficits R = Right T3-L3 or L4-S3

• Decreased withdrawal reflex R pelvic limb = Right L4-S3

-overall localization = Right L4-S3 spinal cord segments

Localize the lesion:

10 yr MI Terrier Mix: Unable to walk

• Tetraparesis

• Postural reaction deficits x4, worse on Right

• Decreased withdrawals in thoracic limbs

(go through each bullet point and localize, then establish the overall lesion localization)

• Tetraparesis = Forebrain, brainstem, C1-C5, C6-T2

• Postural reaction deficits x4, worse on Right = L forebrain, R brainstem, R C1-C5 or C6-T2

• Decreased withdrawals in thoracic limbs = C6-T2 spinal cord segments

-overall localization = C6-T2 spinal cord segments

ID: 1 & 2

1. L4-L6

2. Patellar

ID: 3 & 4

3. L6-S1

4. Withdrawal

ID: 5 & 6

5. S1-3

6. Perineal

ID: 7 & 8

7. C6-T2

8. Withdrawal

ID: 9 & 10

9. C8-T2

10. Withdrawal

ID: 11 & 12

11. C8-T2

12. Withdrawal

ID: 13 & 14

13. C8-T2

14. Cutaneous Trunci

Localize the lesion:

9 yr FS Shep Mix: Dragging L Front leg

• L thoracic limb monoparesis

• Decreased withdrawal

• Absent cutaneous trunci reflex L

(go through each bullet point and localize, then establish the overall lesion localization)

• L thoracic limb monoparesis = L brachial plexus or peripheral N

• Decreased withdrawal = L C6-T2, brachial plexus or peripheral N

• Absent cutaneous trunci reflex L = L C8-T1 nerve roots or lateral thoracic N

-Overall localization = L brachial plexus

Localize the lesion:

5 yr FS Lab: Collapsing in Hind Legs

• Collapses in pelvic limbs with exercise

• Normal gait and NEx when rested

(go through each bullet point and localize, then establish the overall lesion localization)

• Collapses in pelvic limbs with exercise = NMJ

• Normal gait and NEx when rested = NMJ

-overall = NMJ

Localize the lesion: