Spinal cord stroke
Spinal cord stroke is a rare type of stroke with compromised blood flow to any region of spinal cord owing to occlusion or bleeding, leading to irreversible neuronal death. It can be classified into two types, ischaemia and haemorrhage, in which the former accounts for 86% of all cases, a pattern similar to cerebral stroke. The disease is either arisen spontaneously from aortic illnesses or postoperatively. It deprives patients of motor function or sensory function, and sometimes both. Infarction usually occurs in regions perfused by anterior spinal artery, which spans the anterior two-thirds of spinal cord. Preventions of the disease include decreasing the risk factors and maintaining enough spinal cord perfusion pressure during and after the operation. The process of diagnosing the ischemic and hemorrhagic spinal cord stroke includes applying different MRI protocols and CT scan. Treatments for spinal cord stroke are mainly determined by the symptoms and the causes of the disease. For example, antiplatelet and corticosteroids might be used to reduce the risk of blood clots in ischaemic spinal stroke patients, while rapid surgical decompression is applied to minimize neurological injuries in haemorrhagic spinal stroke patients instead. Patients may spend years for rehabilitation after the spinal cord stroke.
Signs and symptoms
Signs and symptoms are related to the portion of spinal cord affected, and appear below the level of lesion. Abrupt onset of pain at the back or neck marks the location of ischaemia or hemorrhage at the beginning, which radiates as the damage intensifies. Temporary paresis in limbs may occur days before the onset of spinal ischaemic stroke, though the relationship remains unclear. While it takes minutes for ischaemic spinal stroke to develop the symptoms, the time could be extended to days and weeks in hemorrhagic spinal stroke. Infarction occurs predominantly in arteries, and the watershed region, which refers thoracic spinal cord here, is highly susceptible to ischaemic attack. Patients with a male gender, younger age, lower body mass index, hypertension, diabetes mellitus, renal insufficiency and chronic obstructive pulmonary disease are predisposed to higher risks of severe spinal cord stroke.Anterior spinal cord syndrome
A major feature is losing motor function such as voluntary movement, reflexes and coordination as a result of compromised anterior and lateral corticospinal tract, anterior grey matter and spinocerebellar tract. There is also a loss in nociception and thermosensation as a result of interrupted spinothalamic tract.Posterior spinal cord syndrome
Sensory functions namely vibration, fine touch, and proprioception are undermined, which are associated to dorsal column. Unlike anterior spinal cord stroke, motor functions are not handicapped in posterior spinal cord stroke.Central spinal cord syndrome
In central spinal cord syndrome, impairment of motor function in the upper body is considerably more severe than that of lower body, which is related to hyperextension of corticospinal tracts and spinocerebellar tract in cervical spinal cord, accompanied by dysfunction in urinary bladder and sensational loss at a varying degree.Brown-Séquard syndrome
is only the subtype that affects the spinal cord unilaterally, either anteriorly, posteriorly, or both. Ipsilateral loss of vibration, fine touch, body position perception and fine movement control, as well as contralateral loss of axial muscles and movement coordination are found. Spasticity followed by dysfunctinoal regulation of muscle tone also exists.Transverse
Death of cells at the complete transverse level is presented clinically as lower paraplegia or quadriplegia, sensory loss below the lesion, urinary incontinence, and disturbances in autonomous nervous system and hormonal system.Causes
Diseases in aorta are recognized as a widely seen contributor of spontaneous spinal cord ischaemia, represented by rupturing of thoracic aortic aneurysm, arterial occlusion by aortic intima separated from endothelial wall in aortic dissection, and aortic coarctation. Embolism, meningeal inflammation at spinal cord, global ischaemia and abusing nicotinic drugs are also identified to factors.Aortic surgeries contribute to many iatrogenic spinal cord ischaemia, although its percentage is much lower than that of spontaneous type. Thoracic endovascular aortic repair was carried out to introduce a stent graft in order to treat thoracoabdominal aortic aneurysm, a condition of enlarged aorta with weakened vascular wall, as well as traumas and atherosclerosis. Segmental medullary arteries, notably the artery of Adamkiewicz, could be excluded from circulation after blockage of intercostal arteries by the device, which directly branches from descending aorta. Furthermore, during open repair, blood flow within aorta is halted by clamping to facilitate the sewing of interposition graft. The reduced blood flow to anterior and posterior radicular artery could trigger spinal stroke. Cases of spinal stroke following operations like aortography, spinal anesthesia and lumbar spine surgery are reported.
Abnormalities in blood vessels including arteriovenous malformations, arteriovenous fistulas and cavernomas are preferably presented as ischaemia and occasionally hemorrhage. The direct fusion between arteries and veins increases blood pressure in radiculomedullary vein and coronal venous plexus, which is an important factor of venous congestive myelopathy and infarction.
Prolonged compression on the blood network by vertebral diseases such as cervical spondylosis and protruded intervertebral disks can be attributed to acute ischaemia in spinal cord, yet the correlation is uncertain.
On the other hand, trauma, which generally originates from terminal vascular network, is a common cause of spinal cord hemorrhage for all four subtypes, namely haematomyelia, subarachnoid hemorrhage, subdural hemorrhage and epidural hemorrhage. There is a correlation between anticoagulating drugs and hemorrhagic stroke.
Causes are often not clearly defined in clinical settings.