myogenic palsies Flashcards

Question

how do the muscles change in eom

Answer 1

First 10 days EOM function normal 11-14 days paretic phase 17-24 days restrictive / mixed phase – resolve / permanent Siatkowski et al (1994) AJO 118:343-50 Isolated involvement of the levator Wheatcroft (1999) BJO 83:628

Answer 2

GO Idiopathic orbital pseudo-tumour Orbital cellulitis Orbital rhabdomyosarcoma

Answer 3

Orthoptic management Make comfortable with prisms whilst wait for recovery Occlusion May have persistent motility problem, if stable for min 3 months consider surgical treatment treatment Bessant & Lee (1995): 5 patients with orbital myositis, describe use of Botulinum Toxin, 2 needed surgery later.

Answer 4

Is a nonspecific, non-neoplastic inflammatory process of the orbit Accounts for 8-11% of all orbital tumours Aetiology: unknown possibly caused by infection, autoimmune disorder and aberrant wound healing Acute onset over a period of days / weeks Onset: any age more likely in adults

Answer 5

Ocular characteristics Proptosis (82%) Periobital oedema Mechanical limitation of eye movements (54%) Pain with and without movement of the eyes Diplopia Erythema (redness of skin) Visual acuity loss (38%)

Answer 6

ocular myositis is a subgroup of orbital pseudotumout enchacement of orbital fat on ct scan granulomatous tissue infiltrated with lymphocytes and plasma cells biopsy may be necessary to differentiate from orbital tumour risks if no improvement

Answer 7

Diagnosis Often by exclusion Lab tests normal Orbital imaging Biopsy

Answer 8

Treatment Steroids Orbital decompression Low dose radiation therapy

Answer 9

Prognosis Long term is favourable 30% recurrence rate

Answer 10

Primary tumour of the muscle (rare) Haemangioma / lymphangioma / neurofibroma / Rhabdomyosarcoma Secondary tumour - Infiltration of a tumour into EOM from orbit / adjacent sinus / bones Lymphangioma / ON glioma / lacrimal tumour Metastases Commonly from skin / breast cancers

Answer 11

Enlargement of muscle Infiltration of tumour Muscle weakness & mechanical restriction ? Associated with Infection / haemorrhage / abscess / cystic lesion Mass effect within orbit Space occupying lesion Mechanical restriction

Answer 12

Fast growing highly malignant tumour of striated muscle Arise from cells called rhabdomyoblast (primative muscle cell), instead of differentiating to striated muscle grows out of control Presents in childhood, typically <5 yrs, 70% <10yrs Head and neck (around eyes) 35-40%, genitourinary tract 20%, extremities 20%, chest/lungs 10-15%

Answer 13

child with protoptosis recent onset diplopia rapid vision changes restricted motility

Answer 14

Symptoms occurring over previous month irritation of left eye watering of left eye blurred vision for approximately 2 weeks Signs LVA 0.14 logMAR L proptosis 3mm L RAPD Restriction of ocular motility bilateral ptosis om -2 limitation all direction of both eyes

Answer 15

CT scan of head and orbits inflammatory mass at the apex of the left orbit presumed pseudotumour Thyroid auto-antibodies / TFTs TFTs include measuring the amount of the thyroid hormones, Thyroxine (T4) or Tri-iodothyronine (T3) and/or the pituitary hormone, Thyroid Stimulating Hormone (TSH) in your blood.

Answer 16

high dose steroids - presidinoslone - 80mg proptosis resolved , no restriction of eye movements steroids reduced gradually over 2months period failure to reduce steroids - without recurrente in symptoms referred for second opinion - biopsy no biopsy due to sudden onset of symptoms over week or months more likely to be due to malignancy steroid maintenance low dose radiotherapy to orbit

Answer 17

histopathology demonstrates ragged red fibres a marker for dysfunction of mitochondrial dna ragged fibres denote the absence of cytochrome oxidase

Answer 18

Orbital cellulitis is an infection that involves the soft tissues posterior to the orbital septum, including the fat and muscle within the bony orbit. It can be associated with severe sight and life-threatening complications and therefore requires prompt diagnosis and initiation of treatment. Orbital cellulitis can occur at any age but is more common in the paediatric population. Orbital cellulitis have been classified by Chandler and Maloney. Chandler classified into preseptal versus postseptal and Maloney into 5 categories. Preseptal tend to occur as a result of insect bites or orbital trauma whereas postseptal usually is a result of acute sinusitis.

Answer 19

Clinical characteristics include: Periorbital oedema Ocular pain Proptosis Chemosis Restricted ocular motility - ophthalmoplegia Reduced visual acuity Conservative management options are often preferred over surgery in patients with orbital cellutis.

Answer 20

An orbital tumour can be a Primary tumour of the extraocular muscle (EOM) which is rare. The tumour can be a haemangioma, lymphangioma, neurofibroma or rhabdomyosarcoma. Secondary tumour caused by infiltration of a tumour into extraocular muscle (EOM) from the orbit, adjacent sinus or bones such as a lymphangioma, haemangioma, optic nerve glioma, lacrimal tumour. Metastases commonly from skin or breast cancers The tumour may cause enlargement of extraocular muscle (EOM) resulting in mechanical restriction and weakness. There may be associated infection, haemorrhage, abscess or cystic lesion.

Answer 21

To diagnose the type of tumour and extent of the tumour, the investigation involves scans and biopsy. A CT scan will identify the location of the tumour and involvement of orbital bone. MRI scan provides visualisation of soft tissue involvement and the location of the tumour in relation to orbital structures such as the optic nerve and extraocular muscles. Orbital tumours can result in orbital congestion, vascular occlusion, and optic nerve compression. Clinical ocular findings may include Proptosis Reduced visual acuity and development of amblyopia in young children Restricted ocular motility and strabismus associated with symptom of diplopia Visual field defect Choroidal folds Compressive optic neuropathy