Spinal arachnoid diverticula and constrictive myelopathy in dogs: different conditions or a spectrum of spinal meningeal disease in veterinary and human medicine?

Different conditions affecting the spinal meningeal layers have been reported in human and veterinary medicine. In veterinary medicine, two separate conditions have been reported. Spinal arachnoid diverticula (SAD) have been well documented for decades, while constrictive myelopathy (CM) in pugs was identified more recently. However, the distinction between SAD and CM in dogs can be challenging. There is a lack of understanding about the pathophysiology of these puzzling conditions, which impacts the ability to select the most appropriate treatment. In humans, four different spinal meningeal diseases are described, including intradural or extradural spinal arachnoid cysts, spinal arachnoid webs, spinal adhesive arachnoiditis, and idiopathic spinal cord herniation. Similar challenges to veterinary medicine are also encountered in human medicine. This brief comparative review aims to emphasize the parallels and obstacles found in both veterinary and human medicine and to explore potential future developments. The term 'spinal meningeal adhesive disease' is proposed as a unified term in veterinary medicine for pathologies affecting the meninges of the spinal cord (SAD and CM), potentially causing progressive clinical signs of myelopathy.