Case Studies
Case 5: Transient neurological dysfunction in a young woman
A 28-year-old lady presents with an episode of painful blurred vision in her left eye which comes on over a week and spontaneously recovers over an eight week period. Six months later she presents with progressive leg weakness which has come on over four days with altered sensation in her legs. She has an aunt with Parkinson’s disease.
On examination she has a nystagmus on left and right lateral gaze, a pale left optic disc on fundoscopy and some subtle but definite incoordination in the left arm. In the lower limbs she has a spastic left leg with loss of joint position sense and vibration perception threshold but reduced pinprick and temperature perception in the right leg to the level of T10.
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MRI showing multiple small plaques of inflammation/demyelination characteristic of MS.
Your Answer:
Correct answer: The most likely diagnosis in this lady is multiple sclerosis given the distribution of neurology over time and space in someone of this age. The initial problem therefore was likely to be one of optic neuritis or inflammation within the left optic nerve. The characteristic visual field defect one sees in patients in the acute stages of optic neuritis are involvement of the central field with a scotoma.
Your Answer:
Correct answer: This lady clearly has Brown-Séquard syndrome in that she has spasticity of the left leg with loss of dorsal column sensory loss on that side but spinothalamic sensory loss in the right leg.
Your Answer:
Correct answer: The lesion must lie in the left side of the spinal cord above the level of T10.
Your Answer:
Correct answer: On the ipsilateral side she has loss of the dorsal columns which project up ipsilaterally to the dorsal column nuclei in the lower medulla before crossing over to form the medial lemniscus. In contrast the spinothalamic tract input (which conveys pain and temperature) crosses on entering the spinal cord and thus passes up contralateral to the side of entry.
Your Answer:
Correct answer: The most likely diagnosis in this lady is multiple sclerosis as she has two neurological episodes separated in space and time involving sites which are preferentially involved in this disease process. The pathophysiological process is inflammatory demyelinating disease of the central nervous system.
Your Answer:
Correct answer: Scanning of the spine would inform you as to whether she has inflammatory lesions in the spinal cord which is important as there is an outside possibility that she has some other cause for her Brown-Séquard syndrome such as a compressive spinal cord lesion. However this seems very unlikely given her age, the absence of pain and the previous history of optic neuritis. The diagnosis of multiple sclerosis is made based on the history and examination, MRI scanning showing inflammatory lesions, CSF examination showing evidence of intrathecal immunoglobulin production and in some cases evoked potentials typically involving the visual pathway to show that there has been previous episodes of demyelination within that pathway with consequent slowing of nerve conduction from the retina to the visual cortex.