Neuro: MS Flashcards
What is multiple sclerosis?
Chronic and progressive condition that involves demylination of the myelinated neurones in the central nervous system.
his is caused by an inflammatory process inolving the acitvation of immune cells against the myelin.
Which patients are typicall effected by MS
Women under 50
When might women specifically see an improvement in MS symptoms?
During pregnancy and the post partum period
What is myelin?
Myelin covers the axons of neurones in the central nervous system.
This myelin helps the electrical impulse move faster along the axon.
Myelin is provided by cells that wrap themselves around the axons.
Which cells provide myelin?
Schwann cells - PNS
Oligodendrocytes - CNS
Which system does MS effect and therefore which cells?
CNS - the oligodendrocytes
Pathophysiology of MS
There is inflammation around myelin and infiltration of immune cells that cause damage to the myelin. This affects the way electrical signals travel along the nerve leading to the symptoms of multiple sclerosis.
What is the pathophysiology behind MS remission?
In early disease, re-myelination can occur and symptoms can resolve. In the later stages of the disease, re-myelination is incomplete and symptoms gradually become more permanent.
What happens during an MS ‘‘attack’’?
Lesions of demyelination occuring throughout the CNS
Specific lesions may cause symptoms (ie. optic neuritis) whilst others do not
Characteristic feature of MS lesions?
Variation in location over time, meaning that different nerves are affected and symptoms change over time
- ‘disseminated in time and space’
Factors that may influence the cause of dyemilination in MS?
Multiple genes EBV Low vitamin D Smoking Obesity
Over what time period do MS symptoms usually progress?
More than 24 hours
Signs and symptoms in MS?
Optic neuritis
Eye movement abnormalities
Focal weakness (bells palsy, horners syndrome, limb paralysis, incontinence)
Focal sensory symptoms (trigeminal neuralgia, numbness, paaesthesia, Lhermitte’s sign)
Ataxia (sensory, cerbellar)
Lesions in the sixth cranial nerve may cause which two disorders?
Internuclear ophtalmoplegia - unilateral lesions
Conjugate lateral gaze disorder - bilateral lesions
What is internuclear opthalmoplegia?
Unilateral lesions in the sixth nerve causes a condition called internuclear ophthalmoplegia.
Internuclear refers to the nerve fibres that connect between the cranial nerve nuclei that control eye movements (3rd, 4th and 6th cranial nerve nuclei).
The internuclear nerve fibres are responsible for coordinating the eye movements to ensure the eyes move together.
Ophthalmoplegia means a problem with the muscles around the eye.
What is conjugate lateral gaze disorder?
Lesions in the sixth cranial nerve cause a conjugate lateral gaze disorder.
Conjugate means connected. Lateral gaze is where both eyes move together to look laterally to the left or right. It is disordered in a sixth cranial nerve palsy.
When looking laterally in the direction of the affected eye, the affected eye will not be able to abduct. For example, in a lesion affecting the left eye, when looking to the left, the right eye will adduct (move towards the nose) and the left eye will remain in the middle as the muscle responsible for making it move laterally is not functioning.
What is Lhermitte’s sign?
An electrical shock sensation that travels down the spinal and into the limbs when flexing the neck
It indicates disease in the cervical spinal cord in the dorsal column.
It is caused by stretching the demyelinated dorsal column.