Myogenic

Ted - wet phase

• wet phase of TED - progressed to mechanical stage

CPEO - chronic progressive external ophthalmoplegia

• benign progressive ocular disorder - occur as isolated condition or widespread

• can be static periods - but progresses to complete CPEO w no remissions

• age 30yrs - hereditary

• or early childhood - rapid deterioration - complete by age of 5

Aetiology

• condition due to primary myopthy of EOM

• inherited e.g. multiple mutations, single deletions

INV- CPEO

CH

• associated w pharyngeal weakness, deafness, optic atrophy, dementia

• familial tendency

• diplopia

• dev

• symmetrical involvement

CT

• hypoT

• ExoT

AHP

• chin elevation

• bilateral ptosis

• frontalis o/a

• FT if large dev - in XT

OM

• limitation in elevation

• then H muslces

• convergence affected last

• ptosis - unilaterl initially - become bilateral - no LPS function

• pupil is unaffected

• absent of Bells phenomenon

FDT

• +ve

Associated clinical signs

• affect facial muscles of mastication

• maybe neck & shoulders

CPEO - MX

• Ptosis props on gls - in complete bilateral ptosis

• poor Bells phenomenon - take into acount

• brow suspension

• ptosis surgery - and corneal cover to prevent exposure Keratits

• prisms or occlusion for diplopia

• surgery not advised - due to progressive nature

  • once OM stable - surgery for cosmetic and AHP

• transposition of v muscle IR & SR - resection

• large LR recession & MR resection

• BT - sm angle manifest dev

MG

• rare disease

• 2 forms

  • ocular involvement

  • or ocular and non ocular

• weakness & fatigue of EOM

  • ptosis / diplopia

• 20-40yrs - F

• Maternally passed

Lambert Eaton MG

• lower limb weakness and autonomic

• is a rare condition that affects the signals sent from the nerves to the muscles.

• muscles are unable to tighten (contract) properly, resulting in muscle weakness and a range of other symptoms.

MG - aetiology

• autoimmune disease

• disorder of neuromuscular junction due to reduction of acetycholine receptors sites and motor end of plate

• causing weakness in skeletal muscles.

• Mechanism: Autoantibodies block or destroy acetylcholine receptors at the neuromuscular junction, impairing muscle contraction.

• Affected Areas: Eyes, face, neck, limbs, and respiratory system.

• Progression: Muscle weakness worsens with activity, improves with rest.

Types of Myasthenia Gravis

Autoimmune Myasthenia (most common)

1. Neonatal Myasthenia – transient, due to maternal antibodies.

2. Congenital Myasthenia – genetic, not autoimmune.

Subtypes:

• Ocular MG – affects eye muscles (ptosis, diplopia).

• Generalized MG – includes eye, facial, neck, limb, and throat muscles.

Most common in women ~40 years and men >60 years.

Symptoms

General: Muscle weakness (arms, legs, face, neck), fatigue.

• Ocular: Drooping eyelids (ptosis), double vision.

• Facial/Throat: Limited expression, speech, chewing, swallowing difficulty.

• Limb: Difficulty lifting arms, standing, walking upstairs.

• Respiratory: Shortness of breath (rare but serious).

• Symptoms fluctuate – worse with activity, better with rest.

Causes

• Autoimmune: Faulty immune response; thymus gland involvement.

• Congenital: Genetic mutation.

• Neonatal: Transferred antibodies from mother.

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Pathophysiology

• Normal: Nerve releases acetylcholine → binds to muscle receptor → muscle contracts.

• MG: Antibodies block receptors → impaired signal transmission → muscle weakness.

risk factors and complications

Risk Factors

• Autoimmune diseases: e.g., lupus, RA.

• Thyroid disorders.

• Triggers: Surgery, infections, certain medications (e.g., for malaria, arrhythmias).

Complications

• Myasthenic Crisis: Respiratory muscle weakness, may need ventilator. Affects ~20% of MG patients.

• Emotional Impact: Stress, depression.

• Physical Limitations: Affects daily life and activity levels.

thymus gland & diagnosis

Thymus Gland Connection

• Thymic hyperplasia: In 2/3 of cases.

• Thymoma: Tumors in 10% (may be benign or cancerous).

Diagnosis

• Physical exam & history.

• Tests:

  • Blood tests: ACh receptor or MuSK antibodies.

  • MRI/CT: Check thymus for tumors.

  • EMG: Measures nerve-muscle communication.

MG Classification (Severity):

1. Class I: Ocular only.

2. Class II: Mild generalized.

3. Class III: Moderate generalized.

4. Class IV: Severe.

5. Class V: Respiratory involvement (needs ventilation).

Treatment

Treatment

• No cure, but symptoms manageable.

Medications:

• Cholinesterase inhibitors – improve nerve-muscle signaling.

• Immunosuppressants – reduce antibody production.

• Monoclonal antibodies – target specific immune cells.

Other Therapies:

• Plasmapheresis – removes harmful antibodies.

• IVIG/SCIG – donor antibodies to suppress immune response.

• Thymectomy – removal of thymus gland.

Lifestyle & Self-Care

• Exercise (moderate, approved by doctor).

• Avoid heat; use cooling techniques.

• Balanced diet (protein & carbs for energy).

• Plan tasks early in the day.

• Rest breaks during the day.

INV

CH

• history of fatigue involving limbs or eyes

• diplopia or INT ptosis

VA

• amblyopia may develop

CT

• decompensated heterophoria or manifest strab

OM

• variable eye signs from visit to visit

• variable ptosis - unilat or bilat

• EOM weakness

• IR paresis

• mimic INO

• pupil normal

• cogan lid twitch

• upper lid retraction

• inv - fatigue - saccades, ptosis & nystagmus

Simpson test

• fatigue on sustained lid and eye elevation is observed

• more affect of fatigue on ptosis than EOM

Cogan lid twitch

• excess innervation to lid on persuit movement to pp

• eye lid retraction

Hess

• variable response

Tensolin

• +ve response - only last few mins

Ach receptor antibody assay

• +ve

EMG

• reduced muscle firing

• thymoma hyperplasia

MG - mx

medical

• anticholinerterase drugs

• corticosteroids

• immunosuppressants

thymectomy

• see autoimmune deficit

prism or occlusion

• pts symptomatic

surgery

• if residual stable dev

BT

• once dev is stable & angle is sm

ptosis

• ptosis props on gls

• brow suspension

• tarsal resection

myotonic dystrophy

• symmetrical external opthalmoplegia EO

• myotonic muscles have abnormal membrane - unable release contraction

primary myopathy

INV

CH

VA

• defective - cataract development

• reduced due to RE

• hypermetropia

• amblyopia

CT

• ET

OM

• Progressive EO

• Ptosis

• sluggish pupil - dilate poorly w mydriatic

Associated clinical signs

• face, neck, limb myopathy w atrophy and baldness

mx

• ptosis props on gls - bilateral ptosis

• surgery for cosmetic & ptosis but variable