SAM N2 - Neurolocalization Above the Foramen Magnum

Instruments needed for neuro exam (3)

Hemostat.

Pleximeter.

Light source.

Forebrain aka Cerebrum divisions and purpose (4)

Frontal - intellect and behavior.

Temporal - emotion.

Occipital - vision.

Parietal - proprioception and nociception.

Divisions of the neuromuscular system (4)

N. root(s).

Peripheral n.

Neuromuscular jctn.

Mm.

Grey matter contains

nuclei of peripheral nn.

White matter contains

myelinated axons.

Forebrain Dz main clinical manifestation

Change in content of conciousness

Forebrain Dz Common CS (5)

Seizures (partial, focal, or generalized).

Altered mental status.

Circling, pacing - direction of the lesion.

Head pressing.

Proprioceptive ataxia.

Which direction are forebrain deficits

Contralateral

Contralateral deficits w/ forebrain lesions include (if focal) (6)

Partial CNN deficits.

CP deficits.

Hemiparesis.

Hemisensory loss.

UMN reflexes.

Visual impairment w/ normal PLR.

Ddx for Lateralizing Forebrain lesions (5)

Neoplasia.

Vascular (stroke/hypertension).

Inflammatory/Infectious.

Traumatic.

Malformation.

Ddx for Diffuse Forebrain Dz (2)

Metabolic.

Toxic.

Thalamic localization - general clinical manifestations (4)

Normal or abnormal gait.

Altered mentation/behavior.

Aggression/excitable.

Circling/Pacing/Head pressing.

Thalamic Localization: What CNN deficit may be seen

Bilateral CNN 2 deficit w/ lesion at the level of optic chiasm - Pupil dilation, visual loss, decreased PLR.

Thalamic Localization: Unique CS (3)

Abnormal temp regulation (hyper or hypo).

Abnormal appetite (increased or decreased).

Endocrine disturbances (DI, DM, Cushing's, Addisons, Seizures)

Brainstem localization - general clinical manifestations

Level of consciousness change, but still appropriate.

Brainstem is regulated by

reticular activating system. Projects information to the cerebral cortex for cognition.

Deficits in the brainstem are seen

ipsilateral to the lesion

CS of Brainstem lesion (6)

Level of consciousness change.

Ipsilateral CP deficits.

UMN (spastic) weakness or paralysis of all 4 limbs or limbs on ipsilateral side.

UMN reflexes ipsilateral to side of lesion.

Ventilatory/PLR changes.

CNN affected by brainstem lesions

Ipsilateral multiple CNN deficits from 3-12 - are complete LMN deficits.

Ddx for Brainstem lesions (5)

Inflammatory.

Infectious.

Traumatic.

Vascular - thromboembolism or thrombocytopenia.

Neoplasia.

cerebellum fxns to

regulate the range, rate, and force of movement.

The cerebellum is a very

inhibitory structure. Dysfxn results in disinhibition and the resultant CS.

Cerebellar localization (5)

Intention tremor (dysmetria of the head).

Pendular or oscillatory nystagmus (dysmetria of the eyes.).

Hypermetria.

Truncal ataxia.

Absence of behavior change aka normal mentation.

Cerebellar localization has an absence of

Proprioceptive deficits or weakness.

Ipsilateral menace response.

Stance of an animal w/ cerebellar lesions

broad based but preservation of strength.

Ddx for Cerebellar signs (5)

Inflammatory.

infectious.

Vascular.

Neoplasia.

Degenerative.

Key features of vestibular dz (3)

head tilt.

vestibular ataxia.

pathologic nystagmus.

Physiologic nystagmus tests and localization (2)

Oculocephalic reflex - forebrain.

Doll's eye reflex - brainstem.

Peripheral vestibular CS (3)

Sustained.

Non-changing.

Rotary or horizontal nystagmus w/ fast phase away from head tilt.

Central Vestibular CS (2)

Changes w/ position.

Rotary, horizontal, vertical downbeat.

Peripheral Vestibular Dz lesion

CNN 8 and its receptor

Peripheral Vestibular Dz CS (5)

Head tilt towards the lesion.

Loss of balance and falling usually towards lesion.

Sustained, non-changing horizontal or rotary nystagmus.

Normal to increased myotatic reflexes.

Strabismus (affected side - "eye drop")

Fast phase of nystagmus in Peripheral Vestibular signs

away from the side of the lesion.

Peripheral vestibular dz has normal (3)

strength.

proprioception.

CNN - except if CNN 7 or Horner's syndrome if otitis media.

Tone w/ peripheral vestibular dz

+/- increased extensor tone on side opposite head tilt

Differentials for Peripheral Vestibular Signs (4)

Otitis media/interna.

Geriatric peripheral vestibular dz.

FB.

Aminoglycoside intoxication.

Differentials for Feline Peripheral Vestibular Signs (2)

Idiopathic peripheral vestibular syndrome.

Nasopharyngeal polyps.

Central vestibular dz can occur w/ lesions of the (3)

Flocculonodular lobe (cerebellum).

Vestibular nuclei (medulla).

MLD (medial longitudinal fasciculus).

CS of central vestibular dz (4)

Head tilt.

Loss of balance/falling.

Positional/Changing nystagmus - horizontal, rotary, or vertical downbeat.

Other brainstem CS of Central Vestibular dz (5)

Ventrolateral strabismus.

CNN deficit CNN5-7 complete LMN.

+/- cerebellar signs.

Change in consciousness level.

Can see V./D.

Deficits seen w/ central vestibular dz

Hemiparesis/CP deficits ipsilateral to lesion.

Central Vestibular Dz from traumatic injury (3)

peracute onset of vestibular signs.

Gradual return to fxn is possible.

Perform serial neuro exams.

DDx for Central Vestibular Signs (5)

Neoplasia.

Inflammatory/Immune.

Infectious.

Vascular.

Toxicity.

Neoplasia that can cause Central Vestibular Signs (4)

Meningioma.

CPP.

Ependymoma.

Mets.

Inflammatory/Immune etiology of Central Vestibular Signs (2)

MUO.

NME.

Infectious etiology for Central Vestibular Dz (4)

Canine distemper.

Fungal - crypto.

FIP.

Extension from middle/inner ear.

Toxicity leading to central vestibular signs

Metronidazole.