Eyelid Neurology

Eyelid and Nictitans Movement

Michael Davidson Professor, Ophthalmology Diplomate, American College of Veterinary Ophthalmologists

Department of Clinical Sciences College of Veterinary Medicine North Carolina State University Raleigh, North Carolina, USA Eyelid Innervation: Efferent Motor  Dorsal ramus of CNIII: – Levator palpebral superioris (opening)  Palpebral and dorsal buccal branches of CNVII: – obicularis oculi (closure) – levator anguli oculi medialis, frontalis, retractor anguli (opening) – malaris mm. (lower eyelid depressor) Eyelid Muscles  Opening: – levator palpebrae superioris m. – frontalis m. – retractor anguli m. – malaris m. – Muller’s m.  Closure: – obicularis oculi m. Eyelid Innervation: Sensory Afferent

maxillary branch  Ophthalmic and ophthalmic branch Maxillary Divisions of CNV mandibular branch trigeminal ganglion trigeminal n. Eyelid Innervation: Sensory Afferent  Ophthalmic division CNV: – Frontal n. = upper eyelid, forehead, frontal sinus Frontal n. – Lacrimal n. = lateral orbit, Infratrochlear n. lacrimal gland, upper eyelid, Short Ciliary n. lateral canthus – Nasociliary n.:

• Long ciliary nerve = cornea, Long Ciliary n. iris, ciliary body, sclera, sympathetics to eye; Nasociliary n. branches of short ciliary Lacrimal n. nerves (parasympathetics to Ophthalmic branch eye) join long ciliary nerve Zygomatic branch and enter eye Maxillary branch • Infratrochlear nerve = medial canthal skin, medial Trigeminal ganglion conjunctiva, sympathetics to Trigeminal n. upper Muller’s mm. Eyelid Innervation: Sensory Afferent

 Frontal n. Maxillary division of CNV: Infratrochlear n. – Zygomatic n. to: Short Ciliary n. Zygomaticotemporal Zygomaticofacial • zygomaticofacial = upper eyelid and conjunctiva • zygomaticotemporal = Long Ciliary n. lower eyelid and Nasociliary n. conjunctiva, sympathetics to lower Ophthalmic branch Muller’s m. and Zygomatic branch parasympathetics to Maxillary branch lacrimal gland Trigeminal ganglion Trigeminal n. Eyelid Innervation: Sympathetic Efferent

 Through terminal Frontal n. branches of trigeminal Infratrochlear n. nerve: Short Ciliary n. Zygomaticotemporal – Infratrochlear n. Zygomaticofacial (ophthalmic division) = upper Muller’s mm. Long Ciliary n. – Zygomaticotemporal n. Nasociliary n. (maxillary division) = lower Muller’s mm. Ophthalmic branch Zygomatic branch Maxillary branch

Trigeminal ganglion Trigeminal n. Reflex Blinking

 optic dazzle (CN II)  menace blink response (entire visual pathway to motor cortex to CN VII with connection to cerebellum)  auditory stimuli (CN VIII to caudal colliculi)  corneal blink reflex (CN V) Corneal Blink Reflex

 subcortical reflex closure of eyelids in response to tactile/painful stimuli  short latency period, fellow eye sometimes responds with blink of lower amplitude  afferent= ophthalmic branch of CN V (long ciliary nerve)  efferent= CN VII  head withdrawal with subsequent (cortical) perception  perform test outside visual field with cotton swab or wisp or Cochet-Bonnet esthesiometer www.osceskills.com

www.scielo.br Corneal Touch Threshold (CTT)

 Minimum amount of force required to elicit corneal reflex  Humans < cat < rabbit < dog  In dogs and humans, central cornea < nasal quadrant < temporal quadrant < dorsal/ventral quadrants  Diabetes mellitus increased CTT Palpebral Reflex

 Closure of eyelids following stimulation of medial canthal region  CN V (ophthalmic division +/- maxillary division) and CNVII (obicularis oculi)  Present 1-4 days postnatally in cats and dogs, and at birth in horses

Ptosis (Greek; ptōsis=fall) Drooping of Upper Eyelid

 Oculomotor (CNIII)  Sympathetic  Paradoxical ptosis (horses)  Non-neurogenic ptosis Oculomotor Ptosis

 denervation of levator palpebrae superioris mm. (CNIII)  innervated by a single midline nucleus (caudal central nucleus)…so midline mesencephalic lesion=bilateral ptosis  pupillomotor & levator m. fibers proximate in CNIII so ptosis and internal ophthalmoplegia can be concurrent  “central” (nuclear or preganglionic) lesions generally assoc. with other midbrain signs Sympathetic Ptosis and Reverse Ptosis

Infratrochlear n.

Long Ciliary n.

Nasociliary n.

Ophthalmic branch Zygomatic branch Maxillary branch

Trigeminal ganglion Trigeminal n. Paradoxical Ptosis in Horses

 Facial nerve paralysis  Atonic supraorbital muscles and paralysis of frontalis muscle cause eyelid drooping  Opposite clinical sign in small animals with facial nerve paralysis

www.horsesidevetguide.com Non-neurogenic ptosis

 Profound illness  Emaciation  Dehydration Pharmacologic Testing of Ptosis

 10% phenylephrine: – Sympathetic ptosis temporarily resolves – Oculomotor (CNIII), paradoxical ptosis (CN VII) and other causes = no effect Facial Nerve Paralysis

 Widened palpebral fissure (no antagonist to levator/Muller’s m.) increased scleral show and illusion of proptosis (“pseudoproptosis”)  “Neuroparalytic” keratitis  “Central” lesion (region of CNVII nuclei or main trunk in medulla): – can also affect cranial nerves V, VI, VIII – possible concurrent neurogenic KCS  “Peripheral” lesion (as CNVII courses through petrosal bone out stylomastoid foramen to eyelids): – can affect CN VIII but not other cranial nerves – no concurrent neurogenic KCS Neurotrophic Keratitis

 ophthalmic division of CN V (long ciliary n. to cornea)  loss of corneal sensation and ulcerative keratitis (lack of tropic influence)

maxillary branch ophthalmic branch

mandibular branch

trigeminal ganglion trigeminal n. Eyelid Closing Abnormalities: Hemifacial Spasm (Tetany)

 irritative lesion to CN VII  can progression to facial paralysis  often from otitis media  So Horner syndrome or neurogenic KCS may accompany Nictitans Anatomy

 Smooth muscle (sympathetic), arising from orbital fascial sheaths of ventral and medial recti mm.

 These fascial sheaths connect smooth muscle of nictitans to bellies of medial and ventral rectii and fascial sheath of dorsal oblique m.

 In cat, slips of striated mm. from lateral rectus and levator palpebral superior mm. attach to ventral and dorsal nictitans respectively Nictitans Protrusion

 All dogs = passive (change in globe position): – globe retraction by retractor bulbii mm. (CN VI) – contraction of other extraocular mm. (CN III, IV, VI) through fascial connections from extraocular mm. to nictitans  Cats = active component – from slips of striated mm. from lateral rectus and levator palpebral superior mm – protrusion can occur independent of globe movement and voluntarily – VIDEO  Non-neurologic protrusion: – changes in orbital volume or position of globe in orbit: • e.g. cellulitis, neoplasia….concurrent exophthalmos • e.g. phthsis bulbi, loss of orbital fat (emaciation)…concurrent enophthalmos Nictitans Retraction

 Sympathetic innervation to smooth muscle: – medial smooth mm. (to dorsal nictitans) • ophthalmic division of CN V ⇒ nasociliary nerve ⇒ infratrochlear nerve (also to upper Muller’s m.) – inferior smooth mm. (to ventral nictitans) • maxillary division of CN V ⇒ infraorbital and zygomatic branches (also to lower Muller’s mm) Über-Localization of Horner Syndrome Scagliotti thought experiment  Efferent sympathetics reach orbit, eye, adnexae through terminal branches of trigeminal n. Frontal n.  Prior to division of three Infratrochlear n. branches of trigeminal n. = ptosis, Short Ciliary n. Zygomaticotemporal reverse ptosis, nictitans Zygomaticofacial protrusion, miosis, +/- enophthalmos  Nasociliary n. (ophthalmic division) = ptosis, nictitans Long Ciliary n. protrusion, miosis, +/- Nasociliary n. enophthalmos, no reverse ptosis  Infratrochlear n. (ophthalmic division, branch of nasociliary n. Ophthalmic branch after long ciliary nerve) = ptosis Zygomatic branch and nictitans protrusion, no miosis Maxillary branch or reverse ptosis  Infraorbital and zygomatic nn. Trigeminal ganglion (maxillary division) = reverse Trigeminal n. ptosis and protruded nictitans, no miosis or upper lid ptosis