Optic Neuropathy

Optic nerve head is the exit site for all retinal nerve fibres. Papillomacular bundle contains the small calibre nerve fibres which subserve the cone system of the fovea . Optic nerve lesions have a predilection for suppression the function of this anatomical structure .

Clinical feature :

· Diminished visual acuity

· Visual field defect - central scotoma

· Diminished pupillary light reflex - Marcus Gunn pupil

· Impairment of color vision

· Diminished light brightness sensitivity

Classification of optic neuropathies

Optic neuritis

inflammatory or demyelinating disorder of optic nerve eg . Multiple sclerosis , postifectious optic neuritis in children with measles , mumps , chickenpox , whooping cough , IM , immunization

Ischaemic optic neuropathy ( AION )

microvascular occlusion of optic nerve head

arteritic eg. giant cell arteritis

nonarteritic (idiopathic )

autoimmune eg. SLE or other systemic collagen vascular disease

Hereditory optic neuropathy

Leber `s hereditory optioc neuropathy - maternal mitochondrial DNA mutation at point 11778 , asymptomatic cardiac anomalies eg. WPW , Lowm Ganong Levine Sx

Toxic optic neuropathy

nutritional eg. alcoholic , smoker , protein def. , vit B def.

drug induced eg. ethambutol , chloramphenicol , isoniazid , streptomycin

Granulomatous optic neuropathy eg. sarcoidosis

Medline Search

· Multiple sclerosis has some features which suggest it is an autoimmune disease .

There is a familial occurrence of multiple sclerosis with thyroid disease and SLE .

· Frequency of anti-nuclear antibodies in multiple sclerosis ( Neurology 1995 Feb. )

ANA 26.7 % of 150 relapsing - remitting MS

30. 4% of 23 chronic progressive MS

Not have SLE

ANA likely reflect systemic immune dysregulation in MS

· Recurrent opticomyelitis associated with anti-DNA antibody ( J- Neurol - Neurosurg-Psychiatry )

2 patients with frequent attacks of acute myelitis and optic neuritis . One patients lacks

any other organ involvement . Another developed systemic manifestations of SLE 14

years after the onset .

· SLE with neurological disorder ( J- Neurol. 1992 Feb.)

6 patients developed a wide variety of neurological manifestations heralded SLE

which included epileptic siezures , stroke , peripheral polyradiculoneuropathy similar

to Guillain Barre Sx . , transverse myelopathy and multifocal disorders with remitting

course mimicking multiple sclerosis

DIFFERENTIAL DIAGNOSIS of multiple central nervous system lesions

· multiple sclerosis

· SLE

· PAN

· Bechet ` s disease

· Acute disseminated encephalomyelitis

· Subacute myelo-optic neuritis

· meningovascular syphilis

· Paraneoplastic effects of carcinoma

· Sarcoidosis

· Lyme disease

· Mulitple emboli from any source

It is important to distinguish multiple sclerosis affecting predominately the spinal cord from other diseases - especially subacute combined degeneration of cord , Tabes dorsalis , Freidreich `s Ataxia and spinal cord compression presenting with root pain and persistent sensory level .

DEVIC SYNDROME

An ill-defined symptom complex known as Devic Syndrome , or

neuromyelitis optica , is considered by some to be an entity distinguishable

from MS . The complex is characterized by acute optic neuritis , usually bilateral , which is followed . or less frequently proceeded , within hours to weeks by transverse myelitis . The CSF may show a pleocytosis with PMN cells and a protein content that is higher than for MS . Pathologic examination

in fatal cases reveals more tissue destruction and cavitation than is expected in MS , although this may bespeak no more than the intensity of the process .

Ku L. K . F/39 married NSND HW

Enjoyed good past health

25/4/95 : blurring of vision Left eye , seen by Eye Unit , Dx optic neuritis , no specific treatment , patient went to China with Dexamethasone IV followed by oral prednisolone given , not improved , total blindness of Left eye

7/7/95 : decrease Right eye visual acuity with patchy visual loss , visited eye clinic , Dx Right optic neuritis , admitted Medical for management .

P/E : Lt eye total blindness , Rt eye decrease visual acuity with central scotoma , fundoscopic finding - Lt : optic atropy , Rt : papillitis

other part of the CNS examination are essentially normal , no cerebellar sign .

No scalp tenderness .

Ixs : VEP : Rt eye flash VEP P100 119msec , Lt eye blind

MRI brain : definite evidence of Left sided optic neuritis . In the brain ,

there is a equivocal focus of subcortical signal changes

located in the left anterior temporal lobe .

CSF : pro 0.5 , glu 4.1 , wcc 7

oligoclonal protein -ve , IgG 6.4 H , Ig A N , Ig M N

Blood Ixs :ESR 22 , RF -ve , ANA 1: 360 , ANTI - ds DNA 48 H

Ig pattern nad , ANCA ++ve , Anti - MPO - ve , C3 , C4 nad

CBP , L/RFT , FBS nad

She was treated with pulse methylprednisolone and prednisolone . Visual acuity of Rt eye improved .

13/10/95 : AROU , admitted surgical , developed bilateral lower limb weakness and numbness 1/7 after admission .

P/E : Rt fundi - nad , Lt fundi - optic atropy

bil. lower limbs UMN lesion with sensory level at T 7 level

cerebellar sign negative

other parts of examination are normal

Ix : myelogram - no obstruction

CSF : total protein 1.20 g/l, glu 3.2mmol/l

wbc 1/cc , rbc 16/cc

oligoclonal protein -ve , Ig G 17.6 H , Ig A 1.3 H , IgM 0.8 N

MRI spine : intramedullary T1w hypointense T2w hyperintense signal

changes were found at level of T4 to T10

VEP : Lt eye blind , Rt eye Flash VEP P100 126 msec

Blood Ixs : ESR 39 , RF -ve , ANA 1:40 , ANTI-DNA -ve

IgG 1294 N , IgA 132.0 N , IgM 19.4 N

CBP , L/RFT , GLU nad

She is treated as a case of Multiple sclerosis with ACTH IMI .Although there is no further neurological deterioration , the recovery is slow . She is on Foley catheter for her urinary retention . She has bilateral lower limbs weakness with power 3/5 of Rt leg and 1/5 of Lt leg .

MULTIPLE SCLEROSIS

AETIOLOGY

unknown , likely to be multifactorial

environmental influence on causation

genetic influence on susceptibility - 10x inc in risk in first degree relatives

higher concordance in monozygotic twin

HLA A3 B7 DR2

immunological cause - inc level of activated T lymphocytes ,inc IG synthesis

in CNS , INC level to some viruses eg measles in CSF

PATHOLOGY

The acute lesion is a plaque , a area of demyelination with swelling of axis cylinders and patchy infilation of inflammatory cells.

CLINICAL FEATURE

relapsing and remitting neurological dysfunction mainly affecting the optic nerves , brain stem , cerebellum and spinal cord

INVESTIGATIONS

· Evoked potential- visual , auditory , somatosensory

· CSF Examination - cell count , Immunoglobin content , protein electrophoresis ( oligoclonal bands )

· Myelogram

· CT/MRI scan

MANAGEMENT

no curative treatment

· specific therapy for the underlying condition

· symptomatic treatment of complications

1. spasticity : baclofen , valium , dantrolene , chemical neuronectomy , physiology

2. Ataxia : isoniazid , clonazepam

3. Dysaesthesia : carbamazpine , dilantin , TCA

4. Urinary symptoms