REM Sleep Disorders and Tetanus?
What is a REM sleep disorder?
Rapid eye movement sleep behavior disorder (RBD) has been defined in humans as repeated episodes of sleep-related vocalization, complex motor behaviors or both documented during EEG evaluation. During normal rapid-eye movement (REM) sleep, all limbs, except the distal limbs, should be atonic. This occurs through an interaction in the brainstem between the pons and medulla. When this system goes awry, motor activity proximal to the toes can be noted and is often found during the REM phase of sleep.
Intoxication by Clostridium tetani can result in impairment of motor function at the level of the spinal cord, resulting in a hypertonic state in dogs. Despite this hypertonicity, abnormal thrashing has been noted with dogs with tetanus intoxication.
As it turns out, RBDs are commonly reported in dogs with tetanus and rare in other animals (even humans) with tetanus. A recent report evaluated a time-locked video and EEG of a 3 month old dog that was hospitalized for presumptive tetanus infection. (See reference below). During hospitalization, the puppy demonstrated thrashing, twitching, chewing movement and vocalization at sporadic intervals. No other signs of seizures were noted. No signs of epilepsy (known as epileptiform waves) were noted throughout the EEG and, most interestingly, shortly after the transition from NREM sleep to REM sleep the dog exhibited the motor activity as described above in 17 of 21 observed REM sleep cycles. This dog was managed for tetanus and provided sedatives in hospital until it was stable for discharge at 21 days. The RBDs continued until 3 weeks post discharge after which time they were no longer seen. I found it interesting that as the RBD improved, it became isolated to just the head before resolving completely.
I thought this was a very interesting study and hope you did too! If you'd like to read the full report you can find it at: https://onlinelibrary.wiley.com/doi/epdf/10.1111/jvim.16585
I hope you have a great week!