Neurologic examination Flashcards
What are the six parts of the neurologic examination?
1) Sensorium and behaviour.
2) Posture and gait.
3) Postural reactions.
4) Spinal reflexes, muscle mass, and muscle tone.
5) Cranial nerves.
6) Cutaneous sensation.
What areas of the neurologic system are responsible for normal sensation?
Cerebrum and reticular activating system (nuclei collected throughout the brainstem)
What are the 4 altered levels of mentation?
1) Depression - slight decreased arousal
2) Obtundation - decreased arousal but responds to voice or touch
3) Stupor - arousal only to vigorous stimuli, response is incomplete or inadequate
4) Coma - unresponsive to stimuli
Altered sensation or mentation suggest what neurolocalization?
Intracranial
What disorders could cause recumbency?
Brainstem, cervical spinal cord, diffuse neuromuscular disease (only brainstem should affect sensorium)
What are the two postures that severe intracranial lesions may cause?
Decerebrate rigidity: opisthotonus and rigid extension of all limbs. Severe impact on mentation. Secondary to midbrain or rostral cerebellar lesions.
Decerebellate rigidity: opisthotonus and rigid extension of limbs with flexion of hip joints. May not impact mentation. Secondary to lesions of the cerebellum.
What components of posture should be assessed as part of the neurologic examination?
Head tilt (vestibular disease)
Head or body turn (forebrain disease)
Neck position (cervical spinal cord or neuromuscular disease)
Hock angle
Trembling (neuromuscular)
Tail position (flaccid with LS disease)
How can gait abnormalities by broadly classified?
Ataxia: disturbances in the vestibular, cerebellar or proprioceptive systems
Weakness: UMN or LMN
Lameness: LMN or orthopedic
Do forebrain lesions typically result in gait abnormalities?
No
Describe the modified Frankel score
Lesions in what location cause a gait disturbance?
Lesions at the level of the midbrain or caudal to it
Is UMN or LMN paresis typically associated with generalized proprioceptive ataxia?
UMN paresis, as the descending UMN pathways are closely associated with the ascending proprioceptive pathways
What are the three forms of ataxia?
- Generalized proprioceptive: UMN lesions of the spinal cord or mid to caudal brainstem.
- Cerebellar: hypermetria +/- head tilt, loss of balance, nystagmus
- Vestibular: falling to one side, incoordination
Do lesions caudal to the brainstem result in ipsilateral or contralateral paresis and proprioceptive ataxia?
Ipsilateral
How can peripheral and central vestibular ataxia be distinguished?
Peripheral: No proprioceptive ataxia. May have Horner’s and facial nerve deficits due to close association of CNVII and sympathetic tracts to the middle ear.
Central: Ipsilateral proprioceptive ataxia and paresis. May have CNVII and CNV deficits (cranial nerve nuclei are close to the vestibular nuclei).
What is the pathway responsible for postural reactions?
Starts with sensory nerves of the peripheral nervous system, enters the spinal cord via the dorsal roots, proprioceptive information ascends in the ipsilateral dorsal and dorsolateral funiculi of the spinal cord. Information remains ipsilateral to the level of the midbrain where conscious proprioceptive information is then relayed to the contralateral thalamus and cerebral hemisphere.
Also relies on UMN and LMN tracts to be intact for appropriate response.
What are some tests that can be performed to assess postural reactions?
Hopping, extensor postural thrust, hemiwalking, wheelbarrowing, paw replacement.
Localize the lesion based on the following flow-chart.
Localize the lesion based on the following flow-chart.
What are the components of a normal reflex arc?
Intact afferent (sensory) arm comprised of the sensory receptor, sensory nerve, dorsal nerve root, and spinal cord segment.
Intact efferent (motor) arm comprised of the lower motor neuron unit.
The afferent and efferent arms enter and exit the spinal cord within the same spinal cord segments.
What spinal cord segments does the patellar reflex test?
Spinal cord segments L4-L6 (femoral nerve)
How can the patellar reflex response be graded?
Absent (0), hyporeflexive (+1), normal (+2), hyperreflexive (+3) or clonic (+4)
What spinal cord segments does the biceps tendon reflex test?
C6-C8 (musculocutaneous nerve)
What spinal cord segments does the triceps tendon reflex test?
C7-T2 (radial nerve)