Jamir Pitton Rissardo
MD | Neurology | Writer | Reviewer | Illustrator | Guitarist ♬
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NeuroTeach 2 - Reflexes and the Eye
Through the eyes!!!
“ocular reflexes are the simplest ocular motor responses”
German psychiatrist Carl Friedrich Otto Westphal (1833–1890)
2) Pupillary light reflex
“constricts the pupil in response to light”
3) Pupillary light reflex – pathway
afferent – CN II
efferent – CN III
4) Relative afferent pupillary defect
“asymmetric afferent output”
- Marcus Gunn pupil
- transient due to local anesthesia
5)‘Reversed’ relative afferent pupillary defect
“one eye has an efferent pupillary defect”
- observe dilation of the unaffected
6) Pupillary escape
“pupil initially constricts to light and then slowly redilates to its original size”
- central field defect
7) Pupillary hippus
“spasmodic, rhythmic, dilating and contracting pupillary movements”
- pupillary athetosis
- usually normal
8) Pupillary dark reflex
“dilates the pupil in response to dark”
9) Pupillary dark reflex – pathway
- central outflow is from the ventrolateral hypothalamus
10) Dilation lag
“abnormal pupil will slowly dilate”
- defect sympathetic innervation of the pupil
- Horner syndrome
11) Westphal-Piltz reflex
“pupillary constriction due to closing eyelids”
- described by Von Graefe, Westphal and Piltz
- oculomotor disinhibition
Figure: Polish neurologist Jan Władysław Piltz (1870 – 1930)
12) Ciliospinal reflex
“pupillary dilation in response to noxious stimuli”
13) Ciliospinal reflex – pathway
afferent: CN V and cervical pain fibers
efferent: sympathetic fibers
14) Ciliospinal reflex
- absent in Horner’s syndrome
- increased/easily elicited in barbiturate-induced coma
15) Near accommodative triad
“directs his eyes from a distant object to a nearby object”
(pupillary accommodation reflex)
+
(lens accommodation reflex)
+
(convergence reflex)
16) Near accommodative triad – pathway
17) Argyll-Robertson pupils
“accommodate but do not react, light-near dissociation”
ARP
(→) Accommodation Reflex Present
(←) Pupillary Reflex Absent
- neurosyphilis, diabetic neuropathy
- pseudo- ARP (Parinaud's syndrome)
18) Adie’s tonic pupil syndrome
“tonically dilated pupil that reacts slowly to light but shows a more definite response to accommodation”
- idiopathic
- unilateral (80%)
- absent ankle jerk + impaired diaphoresis
19) Spasm of the near triad
“triad persists when the patient is not fixating on a near object”
- psychological triggers or stressors
20) Corneal reflex
“both eyes blink in response to tactile stimulation of the cornea”
elicited by foreign bodies, bright light, and sound (>40dB)
21) Corneal reflex – pathway
afferent: CN V
efferent: CN VII
22) Vestibulo-ocular reflex
“eye movements in the opposite direction of head movement”
- maintain steady gaze and prevent retinal image slip
- doll's eyes reflex (positive - intact brainstem)
23) Vestibulo-ocular reflex – pathway
24) Doll's eyes reflex (oculocephalic reflex)
Negative response
“eyes moving towards the same direction of head movement indicating severe brainstem dysfunction”
- Oculocephalic movement test:
> if seizure, oculocephalic movement cannot overcome gaze
> if brainstem, inappropriate activation due to PPRF or CN 3,4,6 lesions
> If frontal eye field, move eyes to both sides
25) Caloric reflex test
Attention!
“Do not confuse the direction of nystagmus (COWS rule) and the direction of motion of eyes”
26) Palpebral oculogyric reflex (Bell’s reflex)
“upward&lateral eye deviation during eyelid closure”
- prominent, LMN facial paralysis & lagopthalmos
- path, afferent VII, efferent III
- supranuclear palsy and local ocular disease
27) Lacrimatory reflex
“causes tear secretion in response to various stimuli”
1. physical and chemical stimuli to the cornea, conjunctiva and nasal mucosa; 2. bright light; 3. emotional upset; 4. Vomiting; 5. Coughing; 6. yawning
28) Bogorad syndrome
“unilateral lacrimation when a person eats or drinks”
- post Bell’s palsy, traumatic facial paralysis
- misdirection of regenerating gustatory fibers from either the facial or glossopharyngeal nerves
29) Optokinetic reflex
“a slow, pursuit phase and a fast ‘reflex’ or ‘refixation’ phase”
- aka optokinetic nystagmus
30) Optokinetic reflex
- r/o malinger
- subclinic internuclear ophthalmoplegia (slower response by medial rectus on lesion side)
- suspect Parinaud syndrome (downward OKN inc convergent retraction moves on upgaze)
- infantile strabismus, if motion stereopsis is present
31) Oculocardiac reflex
“dysrhythmic physiological response to physical stimulation of the eye or adnexa”
- aka Aschner reflex or trigeminovagal reflex
32) Oculocardiac reflex – pathway
afferent: CN V
efferent: CN X
33) Oculo-respiratory reflex
“pressure on eye/orbit/stretching extraocular muscles cause shallow breathing, slowed RR or respiratory arrest”
afferent: CN V
efferent: pneumotaxic centers of the pons, medullary respiratory centers
- reflex not inhibited by atropine
34) Oculo-emetic reflex
“extensive manipulation of extraocular muscles lead to nausea and vomiting”
afferent: CN V
efferent: vomiting center in the medulla, increased CN X output