ANAESTHESIA - STRABISMUS SURGERY

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ANAESTHESIA - STRABISMUS SURGERY
www.anaesthesia.co.in
email anaesthesia.co.in_at_gmail.com
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Strabismus

• Misalignment of the visual axes of the two eyes
• Classification
• Pseudostrabismus
• Heterophoria
• Heterotropia
• Concomitant squint
• Incomitant squint

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Pseudostrabismus

• Prominent epicanthal fold
• Hypertelorism
• No treatment required

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Heterophoria (latent squint)

• Types
• Eso / Exophoria
• Hyper / Hypophoria
• Cyclophoria
• Treatment
• Refraction correction
• Orthoptic exercises
• Prism in glasses
• Surgery

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Heterotropia

• Concomitant strabismus
• Convergent
• Divergent
• Vertical
• Paralytic strabismus

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Strabismus

• Process starts at 3-4 mts of age completed at 6
  yrs
• Usual presentation at 1-6 yrs
• If proper stereoscopic visual development is to
  proceed

Surgical intervention must occur by 4 mts age
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What the patient tells you?

• Deviation of eye (1gt2 or 2gt1)
• Loss of vision
• Eyeache / strain ( ms. fatigue)
• Diplopia (gt towards paralytic ms.)
• Spectacles / Refractive errors
• Headache
• Head tilt

PONV
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What you need to know?

• Confusion / blurring of words
• Photophobia
• Alternating or intermittent squint
• Weakness or drooping of eyelids by evening (MG)
• Vertigo
• Motion sickness

PONV
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Past history of

• Head injury
• CNS infection
• ICSOL/ CNS surgery
• Influenza or measles in childhood
• Prematurity or respiratory distress at birth
• Muscle weakness / Myopathy
• Endocrine disorder

Seizures
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.Past history
MH

• Anaesthetic exposure in past
• Black outs
• Sudden unconsciousness
• ß antagonists

Vaso vagal episodes
OCR
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.Past history

• TB / DM / HTN (vascular lesions CVA)
• Asthma / Allergy
• Chest pain / Palpitations
• Alcohol / Smoking

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Family History

• H/o anaesthetic exposure to family member.

MALIGNANT HYPERTHERMIA
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Examination

• General examination
• Vitals
• Systemic examination (CNS)
• Airway examination
• Ophthalmological examination

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Ophthalmic examination
Abnormal tilt Anatomy altered

• Head position
• Eyebrows, eyelids, cornea, lens
• Deviation of eyeglobe (Exo / Esotropia)
• Pupils (direct / consensual)
• Visual acuity

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Bedside tests

• Cover test
• Cover uncover test
• Alternate cover test
• Hirschberg corneal reflex

Latent squint
Intermittent / alternating squint
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Goals of treatment

• Good cosmetic correction
• Improve visual acquity
• Maintain binocular single vision

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Treatment modalities

• Spectacles (refractive correction)
• Occlusion therapy
• Orthoptic exercises (preop)
• Surgery

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Surgery

• Strengthening Weak muscle
• Resection
• Tucking /plication
• Advancement

• Weakening Strong Muscle
• Resection
• Marginal myotomy
• Myectomy

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Anaesthetic Concerns

• Oculo-cardiac reflex
• Oculo-respiratory reflex
• Postoperative nausea and vomiting
• Malignant hyperthermia
• Systemic effects of ophthalmic drugs
• Association with syndromes Aperts, Crouzons

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Systemic effects of ophthalmic drugs

• Usually only antibiotic is given preop.
• Phenylephrine
• Tropicamide, cyclopentolate
• Ecothiophate
• Epinephrine
• Timolol

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GA Vs RA
GA muscle relaxants RA
Akinesia Anesthesia Excellent Excellent
Surgical condn Good Good
Oculo respiratory ref. Ippv obtunds it Present
OCR Less Present
Better control Airway, CVS -
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What is with Succinylcholine?
Inc. incidence masseter spasm halothane and
succinylcholine in pts with squint
Frequent incidence of Masseter spasm after
Succinylcholine in squint pts
Malignant Hyperthermia
Ass. With myopathy ?
Avoid Succinylcholine and halothane
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.. Succinylcholine?
Extraocular muscles
Cells Multiple NMJs
Abnormal forced duction test (20 min)
Succinylcholine
Repeated depolarizations
Prolonged contracture
Increased muscle tone
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Forced Duction Test

• Distinguish paralytic and mechanical restriction
  of movements (Graves ds)
• Surgeon grasps sclera near limbus and tests full
  range of movt. in all quadrants
• Positive mechanical restriction
• Negative EO ms palsy
• May influence type of strabismus surgery

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Forced Duction Test under GA

• Wait 15 20 min after succinylcholine admn
• Non depolarising muscle relaxants
• Intubate and maintain on deep inhalational
  anesthetic till FDT ? Institute NM blockade

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Preoperative Orders

• Consent
• NPO orders
• Peripheral IV access -20G cannula, RL
• Sedative (BZD) H2 antagonists
• Antiemetics Ondansetron (0.1mg/kg)
  dexamethasone(0.15mg/kg)
• Inj. Atropine 0.02mg/kg (iv gt im)
• Inj. Lidocaine 1.5mg/kg iv

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Monitors

• Pulse oximeter
• NIBP
• ECG
• Temperature
• EtCO2

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Induction Maintenance

• Inj. Propofol / Thiopentone
• Inj. Rocuronium (0.6-1.0mg/kg)
• RAE south polar tube
• M/W O2 N2O Isoflurane / propofol infusion

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Oculocardiac reflex

• Trigeminovagal reflex response manifested as
  cardiac arrythmias hypotension
• may be elicited by pain, pressure and
  manipulation of eyeballs.

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Long and short ciliary nerves (V th )
?
Afferent limb
Ciliary ganglion
OCR
?
Gasserian ganglion
Efferent limb
Impulses from brain stem via X N
HEART
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Triggers
OCR

• Pressure on globe
• Traction EOM, conjunctiva other str.
• Ocular trauma / retrobulbar haematoma
• Performing retrobulbar block
• Manipulation eyelid stretch
• Ocular pain
• Hypoxemia and Hypercarbia

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Medial Rectus
OCR
THEORY More acute the onset and stronger more
sustained the traction , the more likely OCR is
to occur

• Manipulated most often
• Less accessible , requires more force for
  exposure
• Attachment pain sensitive meninges around optic
  nerve

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Arrythmias
OCR

• Bradycardia
• Junctional rhythm
• Atrial ectopic
• AV block
• Ventricular bigeminy

• Multifocal PVC
• Idioventricular rhythm
• Ventricular tachycardia
• Asystole

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Prevention
OCR

• Gentle surgical manipulation
• Adequate depth of anaesthesia
• Normal PaO2, PaCO2, pH
• ECG monitoring
• IV atropine 0.02mg/kg glyco. 0.01mg/kg
• ( single dose protect 30 min)
• Retrobulbar block?

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Treatment
OCR

• Stop surgical manipulation
• Assess normocapnia normoxemia
• Optimize depth of anesthesia
• Returns to NL 20 s
• Arrythmia persists
• Inj. Atropine 0.007mg/kg increments
• Inj. Lignocaine 1.5mg/kg

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Oculo-Respiratory Reflex

• Shallow breathing , ?RR apnea

Long and short ciliary nerves (V th )
Afferent limb
Ciliary ganglion
Sensory nucleus V N
?
Efferent limb
?
Pneumotaxic centre in Pons and Medullary
Respiratory Centre
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Oculo-Kinetic Reflex
Positional information from vestibular apparatus
Sensory input from Visual apparatus
Disturbed CNS PROCESSING

• Nausea Vomiting

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• impulses from extra ocular muscles
• vestibular nuclei III, IV,V
• MLF in reticular formation
• close proximity to vomiting centre
• nausea vomiting

?
?
?
?
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PONV

• Decrease opioids
• Propofol volatile anesthetics
• Decrease or avoid N2O TIVA
• Ondansetron / dexamethasone/ droperidol
• NGT aspiration
• Gentle surgical manipulation
• Adequate hydration
• Lidocaine infiltration

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Postoperative

• Analgesia -
• Inj meperidine 10-25 mg iv
• Inj ketorolac 30 mg iv/ im
• Limbal incision more painful than fornix
  incision
• Oxygenation
• W/F OCR, ORR, PONV
• Monitor 4 hrs

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Effect of anaesthetic agents

• Thiopentone divergence of eyeballs
• NDMR - divergence of eyeballs
• Succinylcholine - Convergence

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Thank You