As most of you know my girl Elsa had a spinal stroke back in February of this year. Seven months later… and she is a different girl. I feel that we are very lucky with her recovery, strength and drive to overcome what has happened to her. She will never be the same, I know that now but she is almost back to our old Elsa. She is doing amazing “chuck it” work, retrieving like a maniac and able to do just about everything she use to do. She is still left with a fear of falling due to her bum leg but we help her with it and adjust life when needed.
The one thing that has left me pondering in all of this is the rapid speed and powerful movement of her limb that was affected the most. Her back left leg took the brunt of the stroke although her other limbs are not quite right. When she is asleep she has such a raised level and strength of movement when dreaming that it’s crazy. Most of the movement comes from that bum left leg which has left me pondering over the last months. How can that leg be bum but move so much? It also moves more than normal when I am trying to cut her nails or trim her feet; which has turned out to be nearly impossible as she kicks like a donkey on steroids.
I am a need to know type of gal and this movement has been driving me to research for information. I contacted members of a Facebook Spinal Stroke page that I am on (yep there’s one) and they all stated that their dogs do the same. With my lingering questions I turned to my amazing nephew who just obtained his Doctorate in Human Neuromuscular Physiology to see if he could help me figure out what is going on with this movement of Elsa’s. Humans are also affected by spinal strokes so I thought that Dr. Davis Forman might be able to assist me.
This all makes sense to me…
Dr. Davis Forman’s perspective as to what is going on with Elsa.
To start off, it’s important to discuss reflexes, and I have an example of a reflex in the photo above. This specific example is called a “stretch reflex,” which is probably the most well known reflex in the body; it’s the one that doctors and therapists will sometimes look into by tapping your knee with a hammer. The way this reflex works is that, 1)when the hammer strikes the tendon just below your knee cap, the quadriceps muscle is very rapidly stretched (because the tendon around the knee cap is connected to the quadriceps muscle). 2)This rapid stretch stimulates certain receptors inside of the muscle, which then transmit a signal through a sensory neuron (blue line in the photo) and into the spinal cord. 3) The sensory neuron makes a direct connection with a motor neuron (red line in the photo) which exits the spinal cord and connects back to the same muscle that was just stretched (quadriceps). 4)The motor neuron causes the stretched muscle to rapidly contract, which in the case of the knee, will cause the foot to kick.
The most important thing about this whole process is that it all occurs without any input from the brain. That’s what makes a reflex a reflex. So, the next time you’re watching a hockey game and a goalie makes a great save, the sports commentator is actually incorrect when the say, “Wow, that goalie has some amazing reflexes!” What the goalie actually has are amazing reactions (which require brain input).
Now, if you’ve been in the doctor’s office before and have had a tendon tap (hammer on knee) performed on you, or if you’ve seen it done on your children, it’s entirely possible that the procedure failed to elicit a kick. This is very common. While reflexes occur entirely within the spinal cord, and do not require input from the brain, the brain can still influence how reflexes function. For most people, the doctor’s office is a stressful environment, and stress can make people very tense. In these situations, the brain can make stretch reflexes less likely to happen; this is referred to in research and clinical settings as “inhibition.” So, for a tense individual, their brain may be inhibiting their spinal cord, which will prevent their knee from kicking when a doctor strikes their knee with a hammer.
However, the brain exerts a certain level of inhibition on the spinal cord even when we’re not stressed out. For example, think about what happens to the muscles of the leg when we walk. Every step we take, either the quadriceps or the hamstrings are stretching (depending on the phase of walking). As I said before, the stretch reflex is triggered by a stretched muscle, so why aren’t our legs kicking and jerking all the time when we walk? The simple answer is that our brain partially inhibits the stretch reflex during walking so that we can achieve smooth and coordinated movement.
Let’s get back to Elsa now. When damage occurs to the spinal cord, either through a spinal cord injury, a spinal bleed, or a spinal stroke, the biggest issue is that the connections between the brain and certain areas of the spinal cord are lost. In Elsa’s case, the number of connections between her brain and her bad leg are fewer than normal. What does this have to do with reflexes? Like I mentioned, the brain’s most important role in reflex function is to provide an appropriate amount of inhibition. When input from the brain is reduced, reflexes can become hyper active or hyper sensitive. This happens in both humans and dogs. For some individuals with spinal cord damage, a tendon tap performed in a doctor’s office will result in a very large kick, much larger than in a person with an undamaged spinal cord. It’s possible that this is contributing to Elsa’s kicking; with reduced brain input to her bad leg, her reflexes are not being properly regulated.
Why is it so much worse at night? Like I mentioned before, even healthy people can fail to show a stretch reflex in a doctor’s office due to stress. The most effective method of finding a stretch reflex is to get the individual to relax. The reason why this works is that it results in less inhibition from the brain. What does this have to do with sleep? We are the most relaxed, and our brains exert the least amount of inhibition, when we are sleeping. So, for Elsa, she already has a problem of reduced inhibition during the day (spinal cord damage), but that’s compounded by a further reduction in inhibition while she’s sleeping.
As for the dreaming, I can really only speculate about this; I didn’t come across any scientific literature on the symptom. My best guess is that her active dreaming is actually the result of her hyper active leg. As I’m sure you’ve experienced yourself, our dreams can be influenced by what is happening around us, from what we see, smell, hear, or touch. If Elsa’s leg is excessively kicking when she’s asleep, that movement could be influencing what she’s dreaming about (she might think she’s running or chasing animals far more often than she normally would).
So when Elsa is awake, it is her lack of movement inhibition that causes her to over kick so to speak. And when she is sleeping it could be this lack of inhibition as well as the fact that her extra kicking creates or adds more vivid movement to her current dream.
Very, very interesting. She is most definitely improved immensely, she is a fighter through and through. This all makes a great deal of sense to me. Having never dealt with a spinal stroke before, it is all new territory. Every dog brings new stuff, be it health or behavior.