Publications | MSWA

Views
8 years ago

MSWA Bulletin Magazine Summer 15 WEB

  • Text
  • Western
  • Australia
  • Multiple
  • Disability
  • Sclerosis
  • Mswa
  • Participants
  • Ndis
  • Progressive
  • Diagnosed
  • Bulletin

What do they mean? Sue

What do they mean? Sue Shapland RN, BN, Cert. MS Nursing. Members have said they would like to know what some of the most commonly used MS jargon actually means. Often when looking up the meanings of these words, even their definitions need explaining! Cerebro-spinal fluid (CSF): the watery fluid that is produced in the brain and continually washes over the brain and spinal cord providing nutrients and cushioning to protect the structures. Lumbar Puncture (LP): a fine needle is inserted into the spinal canal to collect CSF for analysis, i.e. looking for abnormal cells and signs of inflammation. MRI: see the more detailed article on page 13 of this Bulletin. Relapsing-remitting MS (RRMS): the most common type of MS diagnosed. This means people have periods when symptoms flare up aggressively – known as a relapse, attack or exacerbation. This is followed by periods of good or complete recovery – a remission. Secondary progressive MS (SPMS): many people initially diagnosed with RRMS find that over time, often quoted as 10 years, the frequency of relapses decreases but disability gradually increases. As this follows RRMS it is known as SPMS. People’s experiences vary widely. Note: There has been a positive impact due to earlier diagnosis and the introduction of the various MS therapies use for RRMS, which aim to reduce the number and severity of relapses. Primary progressive MS (PPMS): Approximately 10% of people diagnosed with MS have this form of MS in which disability increases from the outset. Various people experience PPMS differently. While some have a persistent increase in disability, others may stabilise or have a gentler worsening of symptoms. Lhermitte’s sign: a sudden sensation, that feels like an electric shock, which passes down the back of your neck and into your spine, and may then affect your arms and legs. It is usually triggered by bending your head forward towards your chest. It can be a symptom of multiple sclerosis but also occurs in other conditions. Uhthoff’s phenomenon or sign: the temporary worsening of MS symptoms – most often visual but sometimes motor (movement or strength) or sensory - caused by an increase in temperature. The visual symptoms may include double vision, reduced sharpness of vision, or black spots appearing before the eyes. Evoked potentials tests: these electrical tests measure the speed of nerve messages along sensory nerves to the brain and are sometimes used in diagnosing MS. These include visual evoked potentials (VEP) which looks at messages sent from the eyes to the brain in response to a flashing chessboard pattern on a computer screen. Testing the speed of sensations from the skin to the brain, somatosensory evoked potentials (SSEP), involves a series of tiny electric shocks to parts of the limb or limbs. Measuring the speed of transmission can show delays which can indicate damage to the nerve pathway/s. Expanded Disability Status Scale (EDSS): is a method of measuring disability in MS and monitoring changes over time. It is widely used in clinical trials and in the assessment of people with MS. The EDSS scale ranges from 0 to 10 in 0.5 increments that represent higher levels of disability. Scoring is based on an examination by a neurologist. MS hug: a symptom of MS where you feel as if you have a tight band around your chest or ribs or a feeling of pressure on one side of your torso. Some people report they find it painful to breathe. Any chest pain should be checked out by a doctor unless you are sure of the cause. The MS hug is not dangerous but any chest pain should be taken seriously just in case it is being caused by something else like heart or breathing problems. It is always best not to assume that everything you are experiencing is due to your MS, but to speak to a health professional straight away. Reference: UK MS Trust A-Z mstrust.org.uk/a-z 12 Summer 2015 The MS Society of Western Australia

What is Magnetic Resonance Imaging (MRI)? Lou Hatter, MS Nurse Specialist An MRI is a sophisticated machine used in neurology to help ‘see’ inside the central nervous system (CNS). The CNS is made up of three parts – the brain, the brain stem and the spine. The MRI works by detecting the magnetic particles in atoms within cells and sending magnetic pulses at different rates and strengths of the electromagnetic pulse through the body. These are picked up by the electromagnetic receiver. The magnetically charged particles in the body’s tissues get lined up with the magnetic pulse and then return (relax) to their positions once the magnetic field is turned off; this is detected by the machine. There are many pulses including long-strong pulses, short-strong pulses, and long and short weak pulses. The MRI programmers use these different pulse/spin sequences to make the different tissue structures in the body stand out from each other. In 20+ years of studying MRIs, the radiologists have discovered that different tissues, e.g. brain, bone, liver, blood, etc., all show up best using different combinations of pulse techniques. They have also discovered that certain combinations of techniques show abnormalities like tumours or scars for example. When you have an MRI scan, they run a number of different scans. There are standard ones, used for pretty much all medical conditions, called T1 and T2 sequences. This depends on how they measure the relaxation of the magnetic particles. Additional scan types are constantly being developed, but the most commonly used additional scan type for MS investigations is called Fluid Attenuated Inversion Recovery (FLAIR). The way MRI works is that different types of matter or tissue give off different levels of energy when placed in a magnetic field. The computer takes pictures of what is being scanned in ‘slices’ and collects the energy signal from each slice. Because of some of the loud banging noises the scanner makes, it can also work out the signal from small cubes of each slice. These cubes are called voxels (short for volume pixels). Each slice provides the information for one image and each voxel provides the information for one pixel in that image. The whole process uses very advanced mathematics, but ultimately, the higher the overall signal from a voxel, the brighter the pixel is on the final image (and the lower the signal, the darker the pixel). In a T1 scan, grey matter gives off a low signal and looks darker in the images than white matter which gives off a higher signal and looks pale grey. The cerebro-spinal fluid (CSF), the fluid in the CNS, gives off the lowest signal and looks black. Everything is reversed in a T2 scan. Grey matter looks pale grey, white matter looks darker grey and CSF looks white. FLAIR is a clever adjustment of a T2 scan which suppresses the signal from CSF. This means grey matter looks pale grey, white matter looks darker grey and CSF looks black. FLAIR is part of the T2 imaging, with a twist. Its purpose is to distinguish things that border on areas of fluid (such as CSF in the ventricles). Different lesions give off different signals. A white matter MS lesion gives off a high signal in T2 and FLAIR scans, looking like a ‘white spot’ against the white matter which is otherwise relatively dark in these scans. T1 imaging is no good for spotting MS lesions unless the lesion has caused the area to ‘die’, or ‘atrophy’, in which case it is called a ‘black hole’ – because of its appearance. The terms ‘hyper intensity’, ‘hyper intense’, ‘high signal’, etc., all refer to the fact that somewhere is brighter/whiter than it should be; hyper = more. ‘Hypo-intensity’, ‘hypo-intense area’, refers to somewhere being darker than it should be; hypo = less. The relevance of these areas depends on their size, shape, location and the type of scan. CSF bathes the brain which means that all the sulci of the brain are full of CSF and thus there is a lot of white on T2 images. Spotting a lesion in amongst lots of perfectly normal white stuff can be tricky however; it is easier in FLAIR images – because there is less white as the CSF appears as black. (Some small white spots can be perfectly normal, they are usually blood vessels.) Sometimes, the neurologist requests a scan with contrast. A T1 scan is taken after an injection with a ‘contrast agent’, usually gadolinium, which looks bright white on the scan. The CNS, i.e. the brain and spinal cord, is protected by the blood brain barrier (BBB) which stops harmful things from getting in; gadolinium normally can’t get through. In MS, cells from the immune system pass through the blood brain barrier and attack the myelin coating of nerves, causing inflammation and damage: a lesion. While this is happening, the lesion is called ‘active’, ‘enhancing’ or ‘contrast enhancing’. The gap the immune system has caused in the BBB allows gadolinium to get in. If the BBB is intact there should be no bright white signs of gadolinium inside the brain or spinal cord. If there are, these show where there are breaches, in other words, where the immune system is actively causing new damage. Contrast is used to show up very new lesions, typically newer than two to six weeks, and to help show which lesions are active and which aren’t as this can be important for deciding on treatments. Adapted from MS Society UK. The MS Society of Western Australia Summer 2015 13

Bulletin