Hello and Welcome to the forum,
First of all, let me say how sorry I am that your are dealing with this with your son, I have 3 boys and can only imagine what you are going through.
There is DEFINITELY some Chiari symptoms there, in fact, with the loss of sensation to hot/cold I am wondering if he has a syrinx too. Did the do a full spinal (cervical, thoracic and lumbar) MRI ? If not, I would insist on a full spinal one immediately. Please see this link for more information of syringomyelia
I would ask your drs about this, who knows if they didn't tell you about the Chiari they may not have told you this either!!
Also, most of us have got NO HELP from NL (neurologists)..Chiari is more in a surgical field so I would find a good NS..hopefully one that specializes in Chiari. Here is the link to the specialist that others here have tried and liked, I know we have at least one member from Ireland so I hope his dr is on this link.
If you do not find one there, if you are able to travel, I would send your DS's scans into The Chiari Institute as they have the most informed drs there. Most of us have found that many NL and even some NS will discount the severity of this condition so you have to keep looking till you find the right one. Having only 9 to choose from, I can see that it will be extremely difficult...and really you should have a pediatric one if you can.
I have heard of several ppl who have had seizures with Chiari and have even been told they have epilepsy too. When the CSF flow is blocked, it can create intense pressure...I never had a full seizure but would get this feeling like my brain was shaking in my head..
Basically, Chiari is best dx by an MRI..some dr's do a CINE MRI too which studies the CSF flow so they can see if there is an overcrowding causing blockage. I don't know if they told you the herniation size or not, but that isn't really what matters, it is how much overcrowding there is and also if there is pressure on the brain stem. I had an EMG done and ENP (evoked nerve potential tests) done b4 I was dx...Those tests did not do a lot for dx anything though..
I too was never told about the Chiari on my MRI for 6 mos while I got worse. It wasn't ever brought up until I got a 2nd opinion from a NS.
If they are monitoring it, they should do an MRI every 6mos and you should report any new symptoms immediately but again, you should see a NS first b/c with his symptoms he needs to get an opinion from the right specialist!!
Again, all of the symptoms you described have been experience by others here..it could completely be Chiari related..
Take care and good luck!