Medical Procedures and Folic Acid
Imaging
Anaesthetics
Folic Acid and other
sources of information here
An MRI scan is a radiological technique which uses magnetism, radio waves and a computer to produce detailed images of body structures. The scanner is a tube surrounded by a giant circular magnet and the patient is placed on a moveable bed which is inserted into the magnet. The magnet creates a strong magnetic field which aligns the protons of hydrogen atoms, which are then exposed to a beam of radio waves. This spins the various protons of the body and the faint signal produced is detected by the receiver portion of the scanner. This information is processed by a computer and an image produced.
The MRI scan is especially useful for imaging both soft and hard tissues of the brain, spinal cord, joints and abdomen and is the most common test used to look at the spine. Images are very clear and provide information that is far more accurate than x-rays. It is an entirely painless procedure with no known side effects. Some patients who dislike enclosed spaces may find it a bit uncomfortable.
From my experience of MRI imaging of the length of my back, the procedure is as follows.
The hospital staff may provide a gown to wear in place of daytime clothes. All metal objects must be discarded and any metallic materials within the body must be notified to the radiologist prior to the scan, and this may preclude the scan. The patient lies on a padded flat-bed, the head is often placed in a soft padded clamp to avoid unncessary movement, and for aural protection ear muffs are worn. To provide comfort on the rather hard flat-bed the knees may be raised on a V-shaped cushion. When (relatively) comfortable, the patient is pushed head-first into the scanner. The tube is just big enough to allow the patient in with 3-4 inches clearance. Patients are told to keep very still, otherwise the images would be blurry. The scanner makes a loud knocking sound, and the sounds vary as the different magnets are used. Some patients may find this quite hypnotic and despite the noise, may fall asleep! The whole process takes about 20-40 minutes, depending on the number of images required and the complexity of the case. The data is then processed into images for your consultant and may be used as a referral point for surgery.
See http://www.spine-health.com/topics/diag/mri/mri_scan02.html and http://www.spine-health.com/topics/diag/mri/mri_scan.html for more details on how MRI scans work.
CT (Roentgen-Ray Computed Tomography)
A beam of x-rays is shot straight through the tissue being scanned. As it comes out the other side, the beam is blunted slightly because it has hit dense living tissues on the way through. Blunting or "attenuation" of the x-ray comes from the density of the tissue encountered along the way. Very dense tissue like bone blocks lots of x-rays; grey matter blocks some and fluid even less. X-ray detectors positioned around the circumference of the scanner collect attentuation readings from multiple angles. A computerised algorithm reconstructs an image of each slice.
SPECT/PET (single photon/positron emission computed tomography)
When radio-labelled compounds are injected in tracer amounts, their photon emissions can be detected much like x-rays in CT. The images made represent the accumulation of the labelled compound. The compound may reflect, for example, blood flow, oxygen or glucose metabolism, or dopamine transporter concentration. Often these images are shown with a colour scale.
Myelogram
This was the "gold standard" for very difficult spinal diagnostic problems. It involves a lumbar puncture using a 22 gauge spinal needle (smaller than the ones used when blood is taken), and then a "radiopaque" dye is injected. The neurosurgeon, or neuroradiologist, can then move the patient around, watching the dye flow over the nerve structures. It is most helpful when there has been prior surgery, particularly when metal instrumentation is present.
The MRI scanner, now also using moving pictures, has now mostly replaced this procedure.
Source of Information: http://www.neurosurgeon.com
General anaesthetics are used for all surgical procedures to repair spina bifida problems. For anyone who has not had a "general" before, the anticipation of it may be frightening but once you know what to expect the fear can be diminished.
Patients are always starved of food and drink for a number of hours before an operation to avoid the risk of vomiting or other complications when anaesthetised. Depending on hospital policy, pre-meds take the form of either prescribed strong sleeping tablets or sedative injections to calm the patient and to induce sleepiness.
The theatre orderlies collect the patient from the ward and the first stop is the anaesthetic room. Here the anaesthetist administers an intravenous dose (into the hand and/or arm) of a fast-acting drug which knocks the patient out for a few minutes while s/he is connected up to a mask to breathe a mixture of gases and vapours to keep them asleep. The dose is adjusted to vary the strength of the vapour and the depth of the anaesthesia, and according to the individual needs of the patient and the operation procedure.
The patient is then taken into the operating theatre and linked up to the anaesthetic station. This consists of: a monitor to measure, as a minimum, blood pressure, heart electrical activity, and blood oxygen levels; vaporisers to carry the anaesthetic vapour to the patient; flow meters to measure the flow of vapours into the patient; the sucker, to remove, usually, saliva and/or vomit; the ventilator which breathes for the patient, and the "circuit" which is a tube carrying gases to and from the patient. Once asleep (and sometimes paralysed for abdominal and chest operations) a tube is passed into the lungs and connected to the ventilator which "breathes" for the patient.
When the operation is over, the anaesthetist reverses the paralysing agent (if used), substitutes pure oxygen instead of the gases, and waits. When the patient is at this stage, s/he is taken to the recovery room and "woken up" by theatre staff. When the staff are happy with the patient's condition, s/he is taken back to the ward to sleep off the anaesthetic. Close observations are usually carried out after spinal surgery which may include testing arm and leg strength, as well as the usual temperature and BP measurements.
Reactions to anaesthetics can vary. The most common one is a very sore throat, croaky voice and a cough afterwards. However, a common reaction is to vomit as the body tried to rid itself of the vapours. A most drastic reaction to the anaesthetic is one instance I know of where my friend's heart stopped four times; they had to stop and reschedule the operation for a few weeks later. It is extremely rare to die under anaesthesia (20 per 3 million people per year) and mainly occurs in desperately ill patients.
Source of Information: this section has been adapted from an article in the Radio Times magazine
Anyone with a family history of neural tube defects should take a 5 mg of folic acid daily. This dosage is only available on prescription. The usual dosage is 0.4 mg per day in tablet form. It is not harmful if too much is taken, as it is excreted naturally.
Folic acid is a water-soluble B-vitamin which is essential for the efficient functioning of the body. In the context of conception and the prevention of neural tube defects, it should be used from the time of ceasing contraception to the 12th week of pregnancy.
There are three ways in which to ensure a sufficient intake of folic acid:
Source of information: The UK Health Information Service (0800 665544), the UK Asbah site, and the Spina Bifida Association of America