Paralytic Strabismus Overview - Kinzer 2023 PDF

STRABISMUS OVERVIEW STRABISMUS • Strabismus: a vision condition in which a person can not align both eyes simultaneously under normal conditions • One or both of the eyes may turn in, out, up, or down • An eye turn may be constant or intermittent CAUSES OF STRABISMUS • Childhood vs Adult Strabi...

STRABISMUS OVERVIEW STRABISMUS • Strabismus: a vision condition in which a person can not align both eyes simultaneously under normal conditions • One or both of the eyes may turn in, out, up, or down • An eye turn may be constant or intermittent CAUSES OF STRABISMUS • Childhood vs Adult Strabismus: • • • • Congenital Accommodative Esotropia Abnormal Visual Development Neurological • • • • • • Onset? Head Trauma? Perinatal History? Other neurological signs? Old Photographs? Head Tilt? TYPES OF NEUROLOGICAL STRABISMUS • Cranial Nerve Palsies (CN III, IV, VI Palsy) • Neurological Diseases (myasthenia gravis, botulism) • Posterior Fossa Tumors or Malformations (Arnold Chiari) • Raised Intracranial Pressure (hydrocephalus, idiopathic, tumor) CRANIAL NERVE PARALYSIS SYMPTOMS • Double vision • Blurry vision • Reduced peripheral vision • Headaches • Dizziness CN 3 PALSY • Oculomotor Nerve Palsy • CN 3 Innervates: • Extraocular Muscles: • Superior Rectus • Medial Rectus • Inferior Rectus • Inferior Oblique Eye Down & Out • Superior Palpebral Levator Muscle  Ptosis • Edinger-Westphal Nucleus  Dilated Pupil  No Accommodative Response CN 3 PALSY • Oculomotor Nerve Palsy • Incomplete/Partial CN 3 Palsy • Consider Posterior Communicating Artery Aneurysm unless proven otherwise CRANIAL NERVE 3 PALSY • Etiology: Children Young Adults Older Adults Congenital Demyelinating Vascular (infarction) Vascular (AV malformations) Vascular (hemorrhage or infarction) Tumor Tumor (primary or metastatic) CRANIAL NERVE 3 PALSY • Etiology: • Ischemic/Vascular • Diabetes (most common cause in adults) • Hypertension • Pupil Sparing (pupils not affected) • Pupillary fibers run along the outside of CN 3 • Vasculature runs in the center of CN 3  Pupils are normal CRANIAL NERVE 3 PALSY • Etiology: • Compressive (Non-Pupil Sparring) • Intracranial Aneurysm • Most Common: Posterior Communicating Artery • Can also involve: Internal Carotid Artery Basilar Artery • Acute: risk of rupture  Subarachnoid Hemorrhage (Pain) • Neoplasm • Primary Tumors: Neuromas, Schwannomas • Tumors adjacent to the nerve: Pituitary, Sphenoid wing meningioma Basilar Artery CRANIAL NERVE 3 PALSY • Etiology: • • • • Trauma • Severe Blows to the Head with Skull Fracture and/or Loss of Consciousness Migraine • • Ophthalmoplegic migraine  from a Recurrent Demyelinating Neuropathy? Children & Young Adults Inflammatory • Multiple Sclerosis Infectious • • Meningitis Viral CRANIAL NERVE 3 PALSY • Tests to Evaluate CN 3 Palsy: • • • • • • • • • Case History: diplopia? decreased vision at near? onset? trauma? External Observation Visual Acuity Cover Test (exo, hypo) EOMs Pupil Testing NPC Accommodation Testing Hess-Lancaster Test CN 4 PALSY • Trochlear Nerve Palsy • CN 4 Innervates: • Superior Oblique  Eye Up & In  Compensatory Head Tilt to Opposite side of palsy • ex. Right Head Tilt  Left Superior Oblique Palsy CRANIAL NERVE 4 PALSY • Pathway: • Longest Intracranial Pathway • Crosses in back of the brain stem  partially encircling the midbrain  decussates after midbrain CRANIAL NERVE 4 PALSY • CN IV Nucleus is near descending sympathetic fibers • Damage to CN IV Nucleus:  Ipsilateral pre-ganglionic Horner’s syndrome • Horner’s Syndrome Triad: Miosis, Ptosis, Anhidrosis  Contralateral Superior Oblique Palsy CRANIAL NERVE 4 PALSY • Etiology: • Congenital • Abnormal development of CN 4 Nucleus OR • Abnormal development of peripheral nerve or tendon CRANIAL NERVE 4 PALSY • Etiology: • Most Common Cause of Acquired Isolated CN 4 Palsy: • #1: Idiopathic • #2: Head Trauma (with loss of consciousness) • Microvasculopathy (diabetes, atherosclerosis, HTN) CRANIAL NERVE 4 PALSY • Etiology: • Includes other Cranial Nerve Palsies: • Tumor • Aneurysm • Multiple Sclerosis • Iatrogenic Injury CRANIAL NERVE 4 PALSY • Tests to Evaluate CN 4 Palsy: • Case History: vertical diplopia? difficulty reading? sense that things are tilted? • External Observation • Cover Test • EOMs • Pupil Testing • Parks Three Step • NPC • Hess-Lancaster CN 6 PALSY • Abducens Nerve Palsy • CN 6 Innervates: • Lateral Rectus Eye turned In • Esotropia • Compensatory Head Turn Towards affected eye • ex. Left CN 6 Palsy  Left Head Turn CRANIAL NERVE 6 PALSY • Pathway: • Long External Course thru Cranium, Susceptible to  • Injury • Increased ICP (Course over Petrous Apex of Temporal Bone) • Mastoid Infection • Skull Fracture • Tumors CRANIAL NERVE 6 PALSY • Presentation: • Lesions of Nerve, Root, Nucleus causes: • Ipsilateral Paresis of Lateral Rectus • Convergent Strabismus increasing in Temporal Gaze • Lateral Diplopia • Ipsilateral Paresis or Paralysis of Facial Muscles for Nuclear Lesions (CN 7 root encircles CN 6 nucleus) CRANIAL NERVE 6 PALSY • Most Commonly affected Oculomotor Nerve in Adults • Second Most Common in Children (CN 4 is most common) • Lateral Rectus is supplied only by a single Anterior Ciliary Artery (other rectus muscles are supplied by two)  more affected by Ischemia than other EOMs CRANIAL NERVE 6 PALSY • Etiology (in no specific order): • Trauma • Aneurysm • Ischemic (HTN, diabetes) • Idiopathic • Demyelination • Neoplasm • Inflammatory • Meningitis CRANIAL NERVE 6 PALSY • Tests to Evaluate CN 6 Palsy: • Case History: horizontal diplopia? • External Observation • Visual Acuity (affected eye can’t fixate) • Cover Test (eso) • EOMs • Hess-Lancaster MULTIPLE CRANIAL NERVE PALSIES • Cavernous Sinus • • • CN 3, 4, 5 (V1 & V2), 6, or Horner’s Syndrome Optic Nerve NOT affected Causes: #1 Neoplasms, Carotid Cavernous Fistula, Aneurysm, Fungal Infection, Inflammation, Tolosa-Hunt • Orbital Apex Syndrome • CN 3, 4, 5 (V1), 6, or Horner’s Syndrome • Optic Nerve Affected • Causes: #1 Neoplasms, Fungal Infection, Inflammation OTHER FORMS OF PARALYSIS SINGLE MUSCLE PALSIES Muscle Presentation Differential Diagnosis • Atypical: Duane’s Retraction Syndrome • Uni/bilateral: Internuclear ophthalmoplegia Medial Rectus Exo-deviation, greater at Near Inferior Rectus Hyper- & Exodeviation • Myogenic: myasthenia gravis • Mechanical limitation: thyroid eye disease • Trauma: blowout fracture Superior Rectus Bilateral, in V Exo pattern • Trauma: blowout fracture • Mechanical limitation: thyroid eye disease • Brown’s Syndrome Inferior Oblique A Eso pattern DOUBLE ELEVATOR PALSY • • • • Superior Rectus & Inferior Oblique of Same eye are affected •  No Elevation in Abduction or Adduction Bell’s Phenomenon is usually present https://www.youtube.com/wa Etiology: • • tch?v=k7Ohg-_umOM Congenital origin Supra nuclear defect Differential Diagnosis (all with Positive Forced Duction Test): • • • • • Blowout fracture Thyroid eye disease Brown’s Syndrome Congenital fibrosis of the inferior rectus muscle General fibrosis syndrome FORCED DUCTION TEST •Resistance Mechanical restriction of muscle  Positive Forced Duction Test •Eye Moves Paretic muscle  Negative Forced Duction Test DOUBLE DEPRESSOR PALSY • AKA Monocular Depression Deficiency • Inferior Rectus & Superior Oblique of Same Eye are affected •  No Depression in Abduction or Adduction • Head tilted down (chin depressed) to compensate for hypertropic eye NEUROGENIC PALSIES • Supranuclear • Internuclear • Nuclear • Infranuclear NEUROGENIC PALSIES • Supranuclear • Lesions above the level of Ocular Motor Nerve Nuclei • Gaze palsies • Tonic gaze deviation (tone of muscle changes towards side of lesion) • Saccadic and smooth pursuit disorders • Vergence abnormalities • Nystagmus • Ocular oscillations (movement back and forth at a regular speed) NEUROGENIC PALSIES • Internuclear • Lesions of the Medial Longitudinal Fasciculus (MLF) • Caused by: • Multiple Sclerosis in younger patients • Vascular Origin in elderly Lesion at Right MLF patients • Internuclear Ophthalmoplegia (INO): impaired horizontal eye movements with weak and slow adduction of the affected eye & abduction nystagmus of the contralateral eye https://www.uptodate.com/contents/internuclear-ophthalmoparesis NEUROGENIC PALSIES • Nuclear • Presentations: • Unilateral CN III with bilateral ptosis • Unilateral CN III with contralateral superior rectus underaction • Isolated extraocular muscle palsy of inferior rectus, inferior oblique, or medial rectus • Bilateral CN III with spared levator function NEUROGENIC PALSIES • Infranuclear • Affects CN III, IV, and VI • CN III Palsy: central, sparing pupil OR peripheral with pupil involvement • If pupil spared  cause is vascular • If pupil involved  cause is likely an aneurysm MANAGEMENT AND TREATMENTS OVERVIEW • Case History (Onset? Medical history?) • Evaluate Strabismus (Cover Test, Hess-Lancaster, EOMs, etc.) • Consider Differential Diagnoses • If suspect a nerve palsy, look at possible causes (Diabetes, Tumor, etc.) • Order additional tests? (MRI? Blood work?) • Once diagnosis is determined, determine best treatment plan. DETERMINE CAUSE OF STRABISMUS • Determine the etiology (i.e., tumor, vascular condition) • Treat the underlying primary condition • If suspect aneurysm or neoplasm  Emergency, seek immediate care • Aneurysm: order an angiography, MRA • Neoplasm: order an MRI or CT scan DETERMINE CAUSE OF STRABISMUS • If Ischemic etiology: • Typically age > 40; sudden onset; HTN/DM/artherosclerosis/smoking • Order: Blood Pressure, CBC, RPR, FTA-Ab, ANA, ESR, CRP, glucose tolerance test if patient does not have HTN or DM • Prognosis: resolves on its own within 3 months • Treatment: systemic factors PRESCRIBING GLASSES • First step in managing strabismic symptoms • Goals: • • improvement of visual acuity can result in improved control of an otherwise uncontrolled deviation introduce prism to correct small deviations • Fresnel press-on prisms for short-term treatment of diplopia, but can also be used long-term (Ground-in Prism for long-term is best cosmetically) • Place Fresnel prism over nondominant eye OCCLUSION • Monocular occlusion as a short-term treatment for diplopia • Good option if expect temporary condition that will resolve or prior to surgical correction • Full-time occlusion is poorly tolerated by patients • Not a good long-term treatment, unless Part-time occlusion during tasks that create diplopia (ex. reading) BOTULINUM NEUROTOXIN • Common treatment for acute paralytic strabismus due to unilateral sixth nerve palsy • Neurotoxic protein that prevents the release of neurotransmitter acetylcholine from axon endings at the neuromuscular junction, resulting in paralysis • Dosage: • • • 1.25 to 5 units into a muscle (inject in overacting muscle) Need repeated procedures Side Effects: temporary • • • • • Soreness at injection site Weakness in the muscles that were injected Muscle soreness that affects your whole body Difficulty swallowing A red rash that lasts several days after the injections SURGERY • Eye muscle surgery for long-term treatment • May also need glasses after surgery • Surgery is meant to weaken, strengthen, or change the vector of force for a given muscle, based on the strabismus https://www.youtube.com/watch?v=-cuTZ71nUYI • Risks: • • • • Mild discomfort following strabismus surgery Continued strabismus Endophthalmitis Ocular ischemia