The neurologic exam (Proceedings)

The neurologic exam is the most important diagnostic test in the evaluation of neurologic disease.

A routine should be used for every exam, just as for a physical examination

     • Easier to perform a complete exam if you have a pattern, especially in non typical scenarios (e.g. spinal cord trauma, painful or fractious animals)

     • Easier to remember all of the components when documenting exam and interpreting findings

Many parts of the exam can be subjective – knowing the expected response of each test in a normal patient makes abnormalities more apparent

     • Examine neurologically normal patients!

Goals of NE

Is patient neurologically normal?

If yes, where is the neuroanatomic localization of abnormality?

     • Brain – cerebrum, brainstem, cerebellar

     • Spinal cord – C1-5, C6-T2, T3-L3, L4-caudal

     • Neuromuscular – neuropathy, junctionopathy, myopathy

     • >1 localization? – multifocal/diffuse disease

Differential diagnoses

     • DAMNIT V

          o Degenerative

          o Anomalous/congenital

          o Metabolic

          o Neoplastic, nutritional

          o Infectious, inflammatory, idiopathic, iatrogenic

          o Traumatic, toxic

          o Vascular

Diagnostic plan formulated from list of likely causes

     • Signalment and history are as important as physical and neurologic examinations in ranking potential causes of signs

An accurate exam is essential in working towards these goals

Components of NE

6 basic categories

     • Mentation

     • Gait/Posture

     • Cranial Nerves

     • Spinal Reflexes

     • Postural Reactions

     • Palpation

Initial observations are valuable

Pay attention to the patient while taking your history

Mentation

     • Alert (bright, quiet)

     • Obtunded (mild, moderate, severe)

     • Stuporous

     • Comatose

     • Additional description as needed – e.g. compulsive, aggressive, hyper-excitable

Gait/Posture

     • Posture, body position at rest

          o Head tilt or turn, leaning, involuntary movements, wide based stance

     • Gait evaluation

          o Ambulatory or non ambulatory

          o Ataxia, paresis, plegia, lameness

               • If plegic, are superficial and deep pain perception present?

          o Other abnormalities associated with movement – e.g. intention tremors, circling, dysmetria

Cranial Nerves

     • CN I (Olfactory)

          o Sensory path for sense of smell

          o Assessed via behavioral response to odors

          o Not often performed clinically

     • CN II (Optic)

          o Sensory path for vision and PLR reflexes

          o Assessed via

               • Behavioral indications of vision

               • Menace response (together with CN VII)

               • PLR reflexes (together with CN III)

               • Visual placing reactions

     • CN III (Oculomotor)

          o Parasympathetic motor fibers for pupil constriction

          o Innervation of extra ocular muscles (dorsal, medial & ventral recti and ventral oblique)

          o Innervation of levator palpebrae muscle

          o Assessed via

               • Pupil size, PLR reflexes

               • Ocular movements (voluntary, physiologic nystagmus)

               • Eye position and palpebral fissure size

     • CN IV (Trochlear)

          o Innervation of dorsal oblique muscle

          o Assessed via observation of pupil (cat) or fundoscopic exam (dog)

     • CN V (Trigeminal)

          o Innervation to muscle of mastication

          o Sensory pathway to the face (ophthalmic, maxillary and mandibular branches)

          o Assessed via

               • Jaw tone, masticatory muscle mass

               • Behavioral or reflex response to stimulation

                     -Palpebral reflex (together with CN VII)

                     -Corneal reflex (together with CN VI VII)

                     -Trigeminofacial reflex (together with CN VII)

                     -Nasal mucosal stimulation

                     -Cutaneous stimulation at lateral maxilla, mandible

     • CN VI (Abducens)

          o Innervation of lateral rectus and retractor bulbi muscles

          o Assessed via

               • Corneal reflex (together with CN V VII)

                   -Ocular movements (voluntary, physiologic nystagmus)

              • Presence of medial strabismus

     • CN VII (Facial)

          o Innervation to muscles of facial expression

          o Sensory path for palate, rostral 2/3 of tongue (taste), inner pinna

          o Innervation to lacrimal and majority of salivary glands

          o Assessed via

              • Menace response (together with CN II)

              • Palpebral, corneal reflexes (together with CN V)

              • Trigeminofacial reflex (together with CN V)

              • Assessment of facial symmetry and movements

              • Cutaneous stimulation of inner pinna

              • Evaluation of tear production (i.e. Schirmer tear test)

              • Response to application of bitter substance to tongue

     • CN VIII (Vestibulocochlear)

          o Sensory path for hearing

          o Sensory path for vestibular input

          o Assessed via

               • Behavioral responses to sound

               • Physiologic nystagmus (together with CN III, IV, VI)

               • Presence of signs of vestibular disease (e.g. strabismus, spontaneous nystagmus, head tilt, lean, etc)

     • CN IX (Glossopharyngeal)

          o Innervation of muscles of pharynx

          o Innervation to zygomatic and parotid salivary glands

          o Sensory path for caudal 1/3 of the tongue

          o Generally considered together with CN X

          o Assessed via

               • Gag reflex

               • Presence of dysphagia

     • CN X (Vagus)

          o Innervation of pharynx, larynx and palate

          o Parasympathetic innervation of viscera

          o Sensory path for caudal pharynx, larynx, viscera

          o Assessed via

               • Gag reflex

               • Presence of dysphagia, stridor, regurgitation, altered vocalization

     • CN XI (Accessory)

          o Innervation of a portion of the cervical musculature

          o Assessed via palpation, symmetry of cervical musculature

          o Deficits rarely appreciated in isolation of other problems

     • CN XII (Hypoglossal)

          o Innervation of muscles of the tongue

          o Assessed via

               • Evaluation of tongue shape, size, symmetry and movements

               • Impairment of prehension, mastication, drinking

Spinal Reflexes

     • Myotatic Reflexes – monosynaptic, 2 neuron pathway

          o Patellar Reflex – L4-6 spinal cord segments (via femoral nerve)

          o Gastronemius Reflex – L7-S1 (sciatic nerve)

          o Biceps Reflex – C6-8 (musculocutaneous nerve)

          o Triceps Reflex – C7-T1 (radial nerve)

     • Withdrawal Reflexes – more complex than myotatic reflexes

          o Pelvic limb – sciatic and femoral nerves and associated segments

          o Thoracic limb – multiple nerves involved

          o Not an indication of pain perception

     • Perineal Reflex – S1-3 (pudendal nerve)

     • Panniculus Reflex – sensory nerves from skin enter spinal cord and synapse bilaterally at C8-T1, motor impulses via lateral thoracic nerves

Postural Reactions

     • With weight support – e.g. proprioceptive positioning, visual and tactile placing

     • Movement associated – e.g. hopping, wheelbarrowing, extensor postural thrust

Palpation

     • Is patient painful? Where? Severity?

     • Range of cervical motion – voluntary, directed

     • Muscle size and tone

     • Bladder size, tone

     • Nail wear

Other parts of the physical examination to consider

     • Orthopedic exam

     • Rectal exam

     • Fundic exam

     • Cardiovascular exam

Feline NE

     • Often limited period of cooperation

     • Gait evaluation, postural reactions can be more challenging

     • Menace response can be more subtle

     • Tendon reflexes may be easier to appreciate

     • Panniculus reflex less reliably obtained

     • Mass reflex can be dramatic with severe myelopathy

Suggested reading:

Handbook of Veterinary Neurology, 4th Ed, Michael D. Lorenz, Joe N Kornegay, Saunders, 2004