1. disorders of the innervation of pupils Flashcards
Causes of myadriasis
- Complete oculumotor nerve lesion
- Adies pupil (tonic pupil)
- Migraine
- Drugs
Causes of miosis
- Horner syndrome
- Argyll-Robertson pupil
- Drugs
Pupil innervation
Sympatetic: dilation
Parasympatetic: constriction
Sympatetic innervation of pupil
- Innervation of dilator pupillae m.
- Dilates the pupil
- Response to decreased light or fight-or-flight-mode
Parasympatethic innervation of pupil
- Oculumotor nerve (short ciliary nerves) innervating sphincter pupillae m.
- Constricts the pupil
- Part of accomodation-convergence reflex
Lesion of symp. inn. of pupil
Horner-triad
Lesion of parasymp. inn of pupil
Myadriasis
Examination of intraocular muscles
- Size and shape
- Direct/indirect pupillary reflex
- Accomodation-convergence reflex
Signs of complete oculumotor nerve lesion
- Myadriasis, ptosis, impaired eye movement on affected side
- Loss of direct pupillary reflex
- Loss of accomodation reaction
Characteristics of Adies pupil
- Bilateral myadris
- Benign, young womem
- Acute onset
Clinical features of Adies pupil
- Myadriasis
- Absent direct and indirect pupillary reflex
- May have reduced/absent limb reflexes (called Holmes-Adie syndrome)
Drugs causing myadriasis
- Anticholinergic drugs
- TCA
- NSAIDS
- Antihistamines
- Oral contraceptives
Location of damage in Horner’s syndrome
Sympathetic damage at:
- brainstem
- cervical cord
- cerv. symp. chain
- middle fossa
- int. carotid a.
- anterior roots of C8 and T1
Etiology of Horner’s syndrome
- Tumor (pancoast)
- Vascular lesions
- Congenital (syringomyelia)
How to distinguish between central and peripheral cause of Horner’s syndrome
If lesion is preganglionic, cocaine in eyes will still cause dilation
Clinical features of Horner’s syndrome
- Ptosis (weakness of sup. and inf. tarsal muscles
- Miosis (weakness of dil. pupillae m.)
- Disturbance of sweating (depends on lesion site)
Clinical features of Argyll-Robertson pupil
- Irregular shaped, small pupils not reacting to light
- Accomodation present
- Do not respond to pupillary dilator drugs
- Usually together with syphilis infection
Drugs causing miosis
Parasympathomimetics:
- Direct acting (muscarinic receptor agonists, pilocarpine)
- Indirect acting (acetylcholinesterase inhibitors, neostigmine, rivastigmine)
Other pupillary disorders
- Failure of accommodation and convergence
- Amaurotic pupil
- Marcus Gunn pupil
- Anisocoria
Causes of failure of accommodation and convergence
- Extrapyramidal diseases (parkinosis)
- Pineal region tumors
What is amaurotic pupil?
Absolute afferent pupillary defect
- lesions of the optic nerve
- direct and consensual light reflex cannot be elicited from affected side
- consensual light reflex can be elicited from normal side (intact oculomotor nerve
Marcus Gunn pupil
Relative afferent pupillary defect
- impaired optic nerve causing decreased response to swinging-flaslight test
Swinging-flashlight test
less constriction when bright light is swung from unaffected to affected side. The affected side still senses the light and produces constriction to some degree (but reduced)
Anisocoria
Unequal pupil size. Fixed and dilated pupil indicates oculumotor lesion. May be caused by transtentorial herniationdue to space occupying lesions, compressing oculumotor nerve
