Some neuros like to do regular MRIs, especially if someone is having relapses, is on a DMD or may need to change DMD. Using contrast is to look for new inflammation that may not be visible yet on non-contrast MRI, although they are using it less these days as there are newer types of scan that do the same job without any injections.
The brain is made up of three main types of stuff, i.e. “matter”: gray matter (the stuff that does all the encoding, processing, storage, “thinking”), white matter (the stuff that carries signals between different bits of gray matter) and CSF (cerebrospinal fluid, the liquid that acts a bit like oil in an engine and the stuff they take a sample of in a lumbar puncture). The outer few layers of the brain are made up of gray matter. This is called the cortex. The white matter lies underneath this. A lesion where the cortex joins the white matter is called a juxtacortical lesion: a lesion “next to/into the cortex”. The CSF bathes the whole brain and spinal cord and is stored in reservoirs in the middle of the brain called the ventricles. The lateral ventricles are the biggest of these, right in the middle of the brain. If you slice the brain from the eyes to the back of the head and look at the slice from the top, the lateral ventricles look a bit like a butterfly. A lesion lying next to these is called periventricular: “next to/touching the ventricles”.
The brain has two halves (hemispheres). Something in one half is called unilateral. Something in both halves is called bilateral.
A lesion that shows up on an MRI scan with contrast is called “enhancing”. This is because the proper name for a scan with contrast is contrast-enhanced MRI. Enhancing lesions are lesions that are actively forming; where the immune system is busy doing damage - in other words, the lesions that are associated with a currrent relapse. Depending on the scan and the scanner, lesions show up on standard MRI after about 6 weeks. Contrast can show where lesions are forming before this, which can be helpful for diagnosis. Contrast also shows where new inflammation is, which is one of the criteria for getting onto a second line DMD (e.g. Tysabri).
So “multiple bilateral enhancing periventricular and juxtacortical lesion” means that the contrast scan showed several active lesions next to the ventricles and the cortex, on both sides of your brain.
I’m a bit confused about CIS and Avonex. I’m guessing you were diagnosed with MS after one of the follow up scans last year and then started on Avonex?
Spinal lesions can affect anywhere in the body from the neck down, but a lesion in the brain can affect anywhere in the body at all. Foot drop is a sign of damage of the “upper motor neuron” which basically means the pathway between the motor cortex of the brain (the bit of the gray matter that controls movement) and the spinal nerves that tell muscles to contract. The left side of the motor cortex controls the right side of the body, but the nerves cross mid way so that the right side of the spinal cord controls the right side of the body. So a lesion in the upper motor neuron in the left side of the brain or a lesion in the upper motor neuron in the right side of the spinal cord could cause foot drop and other upper motor neuron symptoms (e.g. spasticity).
I have to dash now. Hth.