Abstract

Neurological problems presenting in childhood are generally due to congenital lesions, head trauma or central nervous system infections. Multiple sclerosis is rarely considered as a diagnosis in a child living in the tropics but the presentation of recurrent and persistent central nervous system deficits in this child which was confirmed by associated MRI findings, led us to establish this rare diagnosis. 

Introduction

Multiple Sclerosis is a demyelinating disorder of central nervous system with sparing of peripheral nervous system. There are many clinical episodes of neurological deficits involving the cognitive functions, cranial nerves, motor and sensory system and cerebellum. They are recurring in nature and correlate with MRI changes which are diagnostic.MS usually occurs in temperate climate zones and are rarely seen in tropical zones. 

Case Report

A 13 year old female patient xyz presented with the chief complaints of high grade fever since 2 days with chills and rigors, irritability, irrelevant talking, weakness of both lower limbs with inability to stand without support. No history of seizures, loss of consciousness and incontinence of bowel/bladder. There was no headache or projectile vomiting. 

On systemic examination patient was conscious, oriented but hyperactive, indicating a euphoric state. Right facial nerve UMN palsy was present. Power in both lower limbs was grade 3/5, tone was normal, the deep tendon reflexes were exaggerated in all limbs and plantars were extensor bilaterally. There was a subjective sense of paresthesia in rt lower limb. Cerebellar signs were also present -intention tremors on right side, appendicular ataxia, gait ataxia and tandem walking was not possible. 

Further investigations showed- neutrophilic leucocytosis, peripheral smear negative for malaria, serum CRP 42 mg/dl, renal function tests and liver function tests were normal. Cerebrospinal fluid was normal. Fundus was also normal. 

MRI Brain showed multiple patchy areas of altered signal intensity white matter in subcortical and periventricular distribution , appeared confluent and involved bilateral frontal, parietal and temporal (right more than left) and bilateral occipital regions, anterior limb of right internal capsule, callosal septal interface, bilateral cerebral peduncles , pons, midbrain, superior and inferior quadrigeminal tubercles.

Patient had undergone MRI brain previously for similar illness which showed similar pattern. Patient recovered with steroids (iv methyl prednisolone) under the umbrella of broad spectrum antibiotics and fluid support. Patient had significant past history as follows - At around age of 8 yrs patient presented with complaints of high grade fever with chills for 14 days followed by generalized seizures and altered sensorium.

On investigation she was found to have neutrophilic leucocytosis with smear negative for malaria. Cerebrospinal fluid showed raised cell count with increased protein though sugar was in normal range. CECT brain was normal but MRI brain showed T2W hyperintensity lesions in multiple areas with mild communicating hydrocephalus. Tests were also done to rule out G6PD, disorders of fatty acids, amino acids and cystic fibrosis.

Patient was treated with steroids under antibiotic cover. Further serial MRI brain showed similar lesions in brain but spinal cord screening was unremarkable. 

Patient improved clinically with subsidence of fever, became more oriented reacting adequately to vocal commands and improvement in lower limb weakness. Patient could walk without support though cerebellar signs persisted.

In view of presentation of illness, with precipitation of neurological symptoms with fever and dissemination of demyelinating lesions in brain in time and space, after ruling out possibilities of other causes, we reached a conclusion that the underlying pathology should be MULTIPLE SCLEROSIS. 

Discussion

Multiple sclerosis is characterized by a triad of inflammation, demyelination and gliosis of the central nervous system. Lesions of MS typically occur disseminated in time and space. MS is characterized by periventricular plaques. Myelin specific antibodies are present promoting demyelination. As lesions evolve, there is prominent astrocytic proliferation (gliosis).There is partial remyelination of the surviving naked axons producing shadow plaques. Many lesions however fail to remyelinate although oligodendrocyte precursors are present .Peripheral nervous system is spared.

Due to the demyelination, conduction block occurs and the nerve impulse cannot be propagated but later redistribution of sodium channels allows conduction to occur along the naked axon. Chemical fluctuations occur due to variable conduction block. This explains clinical fluctuations that vary from hour to hour .It may appear with fever mimicking meningoencephalitis.

Multiple sclerosis is threefold more common in women than men. Age of onset is 20-40 years (a little later in males than females). Onset in childhood is 0.2-0.4%. Prevalence rates are higher in high latitudes. It is uncommon in Japan, Asia, Africa and the Middle East. 

The onset may be abrupt or insidious. Symptoms are very varied depending upon location and severity of lesions in the central nervous system. The usual symptoms and signs are weakness of the limbs, spasticity, optic neuritis, diplopai, ataxia, bladder dysfunction, cognitive dysfunction, fatigue, facial weakness and vertigo.

Ancillary symptoms are present such as heat sensitivity, Lhermitte’s symptom, trigeminal neuralgia and facial myokymia.

The disease presents with 4 clinical types

1. Relapsing Remitting MS
2. Secondary Progressive MS
3. Primary Progressive MS
4. Progressive Relapsing MS

Diagnostic criteria for MS-

1. There should be objective abnormalities of central nervous system
2. Predominant involvement of long tracts
3. There should be involvement of two or more areas of central nervous system, clinically or by MRI
4. Clinical pattern must consist of two or more episodes of worsening in different sites of central nervous system
5. The neurologic condition cannot be attributed to another disease.

MRI has revolutionized the diagnosis and management of MS. An increase in vascular permeability is detected by leakage of gadolinium into the parenchyma .This produces a MS plaque, focal areas of hyperintensity which remain visible indefinitely. Lesions are perpendicular to the ventricular surface corresponding to the pattern of perivenous demyelination. The lesions are multifocal within the brain, brainstem and spinalcord. There are also hypointense lesions (blackholes) which are markers of irreversible demyelination and axonal loss.

Evoked potential testing and CSF abnormalities help in diagnosis. CSF protein is usually normal but there is mononuclear pleocytosis and an increase in intrathecally synthesised IgG which is measured by oligoclonal bands.

This patient had some rare features of this disease. She presented first at the age of 8 which is very rare. Another uncommon feature was that two of her attacks of MS were precipitated by fever. In some patients attacks of demyelination do occur with fever due to heat in body (Uthoff’s phenomenon). During first episode of demyelination at the age of 8, CSF analysis showed a rise in cell count above 50 cells and a rise in protein content which made the diagnosis of MS unlikely but her serial MRI showed demyelinating plaques disseminated in time and space. She had multiple episodes over the last 6 years and repeat CSF during another attack precipitated by fever neither showed pleocytosis or rise in protein. She fulfills all the 5 diagnostic criteria for definite MS although her presentation is unusual .Even residence in the tropics has low incidence of MS- another unusual feature. 

Conclusion

The diagnostic challenges made this case unique. Although she presented initially with a picture of viral encephalitis, it was later proved to be multiple sclerosis fulfilling the definitive criteria of MS. Hence the presentation. 

Bibliography

1. Nelson’s Textbook of Paediatrics, book 2: 15th edition :chapter552
2. Harrison’s Principles of Internal Medicine: Volume 2: 17th edition:chapter24
3. Harrison’s Principles of Internal Medicine: Volume 2 : 17th edition chapter 375
4. Adam’s Principles of Neurology : 9th edition: chapter 36
5. DeJong’s the Neurogic examination:5th edition :chapter 1