Matheus Cézar Nerone & Gabriel Antonio Covino Diamante
Background: Acute and non-compressive nucleus pulposus extrusion, also called type III disc herniation, usually results from extreme exercises or traumatic episodes and is characterized by an acute extrusion without a compression of the spinal cord. Extrusion reaches the spinal cord at high speed, causing bruising in its parenchyma, and dissipates through the epidural space without causing compression. This report aims to describe the clinical signs, diagnosis and treatment of a canine patient possibly affected by acute non-compressive extrusion of the intervertebral disc, as well as the evolution of the case with the proposed therapy.
Case: A 7-year-old male Dachshund, weighing 9.4 kg, was presented with an acute loss of hind limb locomotion. At the neurological examination, paraplegia of acute onset with absence of deep pain, increased muscle tone, and increased patellar and withdrawal reflexes in hind limbs was found, as well as pain on epaxial palpation of the thoracolumbar spine. The perineal reflex was preserved, and the cutaneous trunci reflex was absent until the level of the second lumbar vertebra (L2). Magnetic resonance imaging (MRI) showed an uncompressed heterogeneous hyper intense area in the thoracolumbar spinal cord on the intervertebral disc (IVD) between T13-L1. Based on the imaging findings, a presumptive diagnosis of an acute non-compressive disc extrusion was assumed, thus discarding the need for surgical decompression. The patient was hospitalized, initially being treated with dexamethasone, tramadol and dipyrone. After 24 hours of hospitalization, the dog recovered deep pain in the pelvic limbs and control over urination. The dog was then discharged from hospital and was prescribed prednisolone and absolute rest. After 25 days of clinical onset, there was a significant improvement in the patient neurological status, presenting only an ataxia of the pelvic limbs. Ten months after the initial care, the owner reported that the patient presented normal, without any gait abnormality or signs of pain, and was in a similar state to the one that preceded the clinical condition.
Discussion: Among the consequences of disc degeneration, acute non-compressive nucleus pulposus extrusion is less frequent than Hansen types I and II. The patients generally affected are older dogs of chondrodystrophic breeds that present hyperacute neurological signs, which may vary from pain to loss of limb movement, depending on location and severity of the injury; signs which are very similar to those described for disc extrusion with compression. However, contrary to what is recommended in the treatment of thoracolumbar extrusion from grade III, decompression surgery is not required in non compressive extrusion, since in this case there is no spinal compression, only spinal concussion, regardless of the degree of neurological injury. The prognosis for dogs that retain the perception of deep pain is generally good. On the other hand, the average recovery rate for dogs that lost the ability to perceive deep pain is much lower. Patients with more severe neurological lesions are usually associated with a worse prognosis; however, the patient presented a positive evolution with conservative treatment, progressing from a paraplegia to an ambulatory paraparesis with a mild ataxia after 20 days of treatment, and showed complete recovery of ambulation after 10 months. Although the loss of deep nociception is a poor prognostic factor, the clinical outcome of this dog suggests that a good recovery may occur with conservative treatment in dogs with acute non-compressive disc extrusion, even in patients with severe neurological signs.