Changes in cerebrospinal fluid pressure and spinal cord perfusion pressure prior to cross-clamping of the thoracic aorta in humans

Little is known about what influences cerebrospinal fluid pressure (CSFP) during anesthesia prior to aortic cross-clamping (AXC). Therefore, this study measured the effect of anesthetic induction, of various drugs administered during the course of surgery prior to AXC, and of hemodynamic changes on CSFP, and calculated spinal cord perfusion pressure (SCPP = mean arterial pressure [MAP] - CSFP) in 11 patients undergoing surgery on the descending thoracic aorta. A lumbar drainage catheter was placed to facilitate drainage of CSF and to measure CSFP. Anesthesia was induced with fentanyl, 50 micrograms/kg, and midazolam, 1 mg, using a pancuronium-metocurine mixture for neuromuscular blockade. Data were collected prior to and after (1) anesthetic induction, (2) mannitol to augment diuresis, (3) sequential use of sodium nitroprusside (SNP) and isoflurane (ISO) to lower MAP by 20%, (4) drainage of spinal fluid, (5) intrathecal injection of papaverine (IP), and (6) AXC. Statistical comparisons of recorded data were made using the least squares mean method and Friedman test. Linear regression was used to test for correlation between CSFP and hemodynamics. Anesthetic induction affected neither hemodynamics nor CSFP. Mannitol significantly increased heart rate, central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), cardiac output (CO), and CSFP (P less than 0.05). SNP or ISO altered neither CVP, PCWP, CO, nor CSFP, which remained elevated at the postmannitol infusion level. ISO, unlike SNP, caused a significant decrease in SCPP (P less than 0.005). Subsequent drainage of 20 mL of CSF improved SCPP (P less than 0.05). IP did not have any effect on hemodynamics or CSFP. CSFP showed a strong correlation with CVP (r = 0.86).(ABSTRACT TRUNCATED AT 250 WORDS)     

Paraplegia after thoracic aortic occlusion: influence of cerebrospinal fluid drainage. Experimental and early clinical results

Paraplegia occurs in 6.5% to 40% of patients after repair of extensive thoracoabdominal aortic aneurysms requiring aortic clamping. This study aimed to determine whether drainage of cerebrospinal fluid (CSF) done before aortic cross-clamping could decrease the incidence of paraplegia in dogs. The descending thoracic aorta was clamped distal to the left subclavian artery for either 40 minutes (group I) or 60 minutes (group II). All control animals in group I (10) and group II (10) showed evidence of spinal cord injury with paraparesis or paraplegia. In contrast, 9 of 10 animals (90%) in group I and 7 of 10 animals (70%) in group II that had CSF drainage before aortic cross-clamping were neurologically normal (p less than 0.001 and p less than 0.01, respectively). Aortic pressure distal to the aortic cross clamp was the same in all groups; however, spinal cord perfusion pressure (distal aortic pressure minus CSF pressure) was significantly higher in neurologically normal animals (34 +/- 5 mm Hg, n = 15) compared with those with paraparesis (26 +/- 4 mm Hg, n = 8) or paraplegia (19 +/- 5 mm Hg, n = 8) (r = 0.871, p less than 0.001). This study demonstrates that drainage of CSF before thoracic aortic occlusion significantly increases spinal cord perfusion pressure and decreases the incidence of paraplegia. Limited early clinical experience suggests that CSF drainage may be a useful adjunct to prevent paraplegia in patients who are having repair of thoracoabdominal aortic aneurysms.     

Mechanism of increased cerebrospinal fluid pressure with thoracic aortic occlusion

Recent clinical reports have suggested that drainage of cerebrospinal fluid lowers the incidence of perioperative paraplegia in patients with thoracoabdominal aneurysms. Unfortunately, the precise mechanisms for both the neurologic deficits and the beneficial effects of cerebrospinal fluid drainage remain unclear. To better understand the relationship between cerebrospinal fluid pressure, central venous pressure, and the compliance of the cerebrospinal fluid compartment, we studied 12 anesthetized dogs subjected to thoracic aortic occlusion. Pericardia were opened in six (group I), and left intact in six (group II). Systemic hemodynamics and cerebrospinal fluid pressure (mm Hg) were measured before and after thoracic aortic occlusion. In group II, intravenous volume loading (15 ml/kg) was superimposed on aortic occlusion. Compliance of the cerebrospinal fluid space (ml/mm Hg) was measured at each interval by use of sequential injection and withdrawal of small aliquots of fluid. Results are expressed as mean +/- SE; *p less than 0.05. Thoracic aortic occlusion resulted in predictable changes in mean arterial pressure (group I 95.8 +/- 7.1 to 123.3 +/- 7.1*, group II 82.5 +/- 6.9 to 98.3 +/- 9.5*) and central venous pressure (1.9 +/- 0.7 to 3.8 +/- 0.6*, 3.0 +/- 0.8 to 4.0 +/- 0.9*). Although cerebrospinal fluid pressure was increased by thoracic aortic occlusion in both groups (8.0 +/- 1.2 to 12.6 +/- 1.9*; 5.8 +/- 0.9 to 8.5 +/- 1.1*), compliance of the dural space was was not changed (0.61 +/- 0.19 to 0.60 +/- 0.18; 0.54 +/- 0.14 to 0.62 +/- 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)     

Longitudinal study of cerebral spinal fluid drainage in polyethylene glycol-conjugated superoxide dismutase in paraplegia associated with thoracic aortic cross-clamping

It has been hoped that pharmacologic prophylaxis in thoracic aortic cross-clamping may avert the unpredictable complication of spinal cord paraplegia, may avoid the mechanical difficulties associated with shunts, partial bypass, or monitoring devices, and may serve as a substitute for or as an adjunct to cerebral spinal fluid drainage. Toward this end 21 mongrel dogs were studied in four groups and underwent 60 minutes of thoracic aortic cross-clamping: group I, five with thoracic aortic cross-clamping; group II, five with thoracic aortic cross-clamping and cerebral spinal fluid drainage; group III, five with thoracic aortic cross-clamping, cerebrospinal fluid drainage and intravenous administration of a single dose (5000 units/kg) of polyethylene glycol-conjugated superoxide dismutase (PEG-SOD) given 15 to 20 minutes before thoracic aortic cross-clamping; and group IV, six with thoracic aortic cross-clamping and PEG-SOD. Paraplegia was graded by the Tarlov method at 24 hours and up to 5 days after thoracic aortic cross-clamping. The carotid and femoral artery pressures, the central venous pressure, and core temperature, taken during the experiment and at the time the dogs were killed, were found to be similar between groups. At 24 hours all dogs in group I were paraplegic; groups II and III had no paraplegic dogs (p less than 0.01), and group IV had fewer paraplegic dogs (two of six) than group I (p less than 0.05). Paraplegia was averted in all dogs treated with cerebral spinal fluid drainage, even 5 days after thoracic aortic cross-clamping.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cerebrospinal fluid drainage and steroids provide better spinal cord protection during aortic cross-clamping than does either treatment alone

We investigated whether intravenous methylprednisolone (30 mg/kg) before 30 minutes of aortic cross-clamping and after 4 hours could enhance the effects of cerebrospinal fluid drainage on spinal cord perfusion pressure and postoperative paraplegia when proximal blood pressure was controlled with sodium nitroprusside and partial exsanguination. Dogs were randomized into three groups: group 1 (n = 6), control; group 2 (n = 7), steroids; and group 3 (n = 6), steroids with cerebrospinal fluid drainage. During aortic cross-clamping, blood pressure proximal to the clamp decreased significantly in each group compared with baseline (p less than 0.05), but did not differ among groups (group 1 = 82.2, group 2 = 82.1, group 3 = 86.6 mm Hg, p greater than 0.05). Mean distal pressure decreased from systemic values to 8.4, 8.5, and 3.7 mm Hg, respectively, after aortic cross-clamping (p less than 0.05); these values did not differ from one another (p greater than 0.05). During aortic cross-clamping, cerebrospinal fluid pressure in groups 1 and 2 did not differ significantly compared with baseline (12.2 versus 8.2, 14.2 versus 10.7 mm Hg, p greater than 0.05), whereas in group 3 the baseline cerebral spinal fluid pressure of 10.7 mm Hg decreased to 0.4 mm Hg (p less than 0.05). Spinal cord perfusion pressure in group 3 was significantly higher than in groups 1 and 2 (3.3 versus -3.9 and -5.7 mm Hg, p less than 0.05), but did not differ between groups 1 and 2 (p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Cross-clamping of the thoracic aorta. Influence of aortic shunts, laminectomy, papaverine, calcium channel blocker, allopurinol, and superoxide dismutase on spinal cord blood flow and paraplegia in baboons.

There is a high incidence of paraplegia associated with thoracic aortic cross-clamping, even when cardiopulmonary bypass or shunts are used. In 56 adult baboons, spinal cord blood flow (SCBF), vascular anatomy, and paraplegia rates were evaluated. Tissue blood flow was measured by radioactive microspheres. Various procedures were used to increase SCBF and to prevent ischemia-reperfusion injury. It was found that the rate of paraplegia was inversely correlated with neural tissue ischemia (SCBF) and directly correlated with reperfusion hyperemia. Two methods completely prevented paraplegia. These two methods were a thoracic shunt with occlusion of the infrarenal aorta or cerebrospinal fluid drainage plus intrathecal papaverine injection, both of which were associated with an increased SCBF. Furthermore, papaverine dilated the anterior spinal artery (ASA) (p = 0.007) and increased the blood flow through the lower ASA. Whereas procedures utilizing a calcium channel blocker (flunarizine), allopurinol, superoxide dismutase (SOD), laminectomy alone, and a thoracoabdominal shunt not perfusing the arteria radicularis magna (ARM) all failed to prevent paraplegia, allopurinol (p = 0.026) and SOD (p = 0.004) did prevent gastric stress lesions, indicating that their failure to prevent paraplegia was not due to a lack of activity. Of great clinical interest is that, if a shunt is used and the ARM is perfused, infrarenal aortic cross-clamping increases SCBF, thus preventing paraplegia. Intrathecal application of papaverine proved to be even more effective in increasing SCBF and also completely prevented paraplegia. As this is a safer procedure than the insertion of shunts, this is the method of choice for the prevention of paraplegia associated with thoracic aortic cross-clamping. The preliminary trial using intrathecal papaverine in human beings has thus far shown no adverse side effects from the drug, and no paraplegia has occurred.     

Effects of thoracic aortic occlusion and cerebrospinal fluid drainage on regional spinal cord blood flow in dogs: correlation with neurologic outcome

We studied the effect of thoracic aortic occlusion and cerebrospinal fluid (CSF) drainage on regional spinal cord blood flow and its correlation with neurologic outcome. Using isotope-tagged microspheres, we determined blood flow to the gray and white matter of five regions of the spinal cord in dogs: group I (control), group II (cross-clamp only), group III (cross-clamp plus CSF drainage). At 60 minutes after thoracic aortic occlusion in group II, median gray matter blood flow (GMBF) in the lower thoracic and lumbar cord decreased from 23.1 and 27.0 ml/100 gm/min at baseline to 4.0 and 2.5 ml/100 gm/min, respectively. The addition of CSF drainage improved GMBF during aortic cross-clamping in the lower thoracic and lumbar cord to 11.3 (p less than 0.05) and 15.1 ml/100 gm/min (p less than 0.03), respectively. After removal of the aortic cross-clamp, median blood flow more than tripled from baseline blood flow in group II, whereas CSF drainage prevented significant reperfusion hyperemia. Both low GMBF during cross-clamping and reperfusion hyperemia were associated with a worse neurologic outcome. In group II, no dog was neurologically normal, and more than 60% of the dogs had spastic paraplegia. In contrast, almost 60% of dogs in group III were normal, and none had spastic paraplegia (p less than 0.001). We conclude that CSF drainage in dogs during thoracic aortic occlusion maintained spinal cord perfusion above critical levels, diminished reperfusion hyperemia, and improved neurologic outcome.     

A prospective randomized study of cerebrospinal fluid drainage to prevent paraplegia after high-risk surgery on the thoracoabdominal aorta

This article is concerned with the study of the effect of several variables, principally that of cerebrospinal fluid drainage, on the incidence of neurologic deficit in a prospective randomized series of patients with extensive aneurysms of the descending thoracic and abdominal aorta (thoracoabdominal type I and II). Forty-six patients had cerebrospinal fluid drainage, and 52 were controls, with a total of 98 available for study. Cerebrospinal fluid pressure was continuously monitored in the former group and pressure maintained less than or equal to 10 mm Hg in 20, less than or equal to 15 mm Hg in 20, and greater than 15 mm Hg in 6 patients during period of aortic clamping. The method of treatment including reattachment of intercostal and lumbar arteries (p = 0.2), temporary atriofemoral bypass during aortic occlusion (p = 0.3), and spinal fluid drainage (p = 0.8) were not statistically significant in reducing the incidence of neurologic deficits. Thus cerebrospinal fluid drainage as we used it, was not beneficial in preventing paraplegia. On appropriate statistical analysis we found that the only significant predictor of delayed deficits was postoperative hypotension (p = 0.006).     

The effect of cerebrospinal fluid drainage on cerebral perfusion in traumatic brain injured adults

Cerebrospinal fluid drainage is a first line treatment used to manage severely elevated intracranial pressure (> or = 20 mm Hg) and improve outcomes in patients with acute head injury. There is no consensus regarding the optimal method of cerebrospinal fluid removal. The purpose of this investigation was to determine whether cerebrospinal fluid drainage decreases intracranial pressure and improves cerebral perfusion and to identify factors that impact treatment effectiveness. This study involved 31 severely head injured patients. Intracranial pressure and other indices of cerebral perfusion (cerebral perfusion pressure, cerebral blood flow velocity, and regional cerebral oximetry) were measured before, during, and after cerebrospinal fluid drainage. Arterial and jugular venous oxygen content was measured before and after cerebrospinal fluid drainage. Patients underwent three randomly ordered cerebrospinal fluid drainage protocols that varied in the volume of cerebrospinal fluid removed (1 mL, 2 mL, and 3 mL) for a total of 6 mL of cerebrospinal fluid removed. There was a significant change in the intracranial pressure from a mean at baseline of 26.1 mm Hg (SD = 4.4) to 22.1 mm Hg immediately after drainage. One third of patients experienced a decrease in the intracranial pressure below 20 mm Hg; in two patients the intracranial pressure dropped less than 1 mm Hg. The following factors predicted 61.5% of the variance in the responsiveness of intracranial pressure to drainage: vecuronium hypothermia, baseline cerebral perfusion pressure and acuity of illness. Cerebrospinal fluid drainage provides a transient decrease in intracranial pressure without a measurable improvement in other indices of cerebral perfusion.     

Intracranial hemorrhage associated with cerebrospinal fluid drainage during thoraco-abdominal aortic surgery

A 69-year-old woman underwent thoraco-abdominal aortic aneurysm repair with cerebrospinal fluid drainage (CSFD). The initial CSF pressure was elevated to approximately 25 cmH₂O, and clear CSF was continuously drained at a rate of 30 ml/h with the drainage level at 10–20 cmH₂O. The CSF became bloody when cardiopulmonary bypass was terminated. The total volume of CSF drained was approximately 300 ml at the conclusion of the 638 min operation. Three hours later, she suffered a series of generalized seizures because of intracranial hemorrhage (ICH). It was suggested that excessive drainage of CSF was associated with ICH. Meticulous control of drainage volume combined with standard pressure-based management may be the key to avoiding these complications.     

The effect of continuous drainage of cerebrospinal fluid in patients with subarachnoid hemorrhage: a retrospective analysis of 108 patients

The effects of continuous drainage of cerebrospinal fluid (CSF) on vasospasm and hydrocephalus were analyzed retrospectively in 108 patients with subarachnoid hemorrhage (SAH) who were operated on for ruptured aneurysms within 48 hours of their onset. Ninety-two of these patients underwent a procedure for CSF drainage (cisternal drainage, ventricular drainage, lumbar drainage, or a combination of these). The duration, the total volume, and the average daily volume of CSF drainage were 10.4 +/- 7.0 days (mean +/- SD). 2034 +/- 1566 ml, and 190 +/- 65.3 ml, respectively. Patients with a greater drainage volume at a lower height of drainage in the early period after SAH developed more cerebral infarctions later (P less than 0.025). The relationship between the total volume of CSF removed and shunt-dependent hydrocephalus was determined to be statistically significant (P less than 0.005). Cerebral infarction and hydrocephalus after SAH were also found to be statistically associated (P less than 0.001). Thus, continuous cerebrospinal fluid drainage should not be performed too readily in patients with SAH, because the removal of a large amount of CSF can induce cerebral vasospasm as well as hydrocephalus.     

Spinal cord injury in experimental thoracic aortic occlusion: investigation of combined methods of protection.

The efficacy of combined methods of spinal cord protection during thoracoabdominal aortic reconstruction was evaluated because a recent clinical study failed to substantiate the value of cerebrospinal fluid drainage when used alone in the prevention of paraplegia. The effect of cerebrospinal fluid drainage and aortofemoral shunting were analyzed with regard to neurologic outcome and spinal cord blood flow in a model of thoracic aortic occlusion. In addition, we studied the use of motor-evoked potentials as compared with somatosensory-evoked potentials in monitoring cord perfusion. Thirty-two dogs underwent proximal and distal thoracic aortic occlusion for 60 minutes. The control group (n = 8) underwent thoracic aortic cross-clamping only. Spinal cord protection was used in three groups: cerebrospinal fluid drainage alone (n = 8), aortofemoral shunting alone (n = 8), and cerebrospinal fluid drainage and aortofemoral shunting (n = 8). Neurologic outcome improved in all treatment groups as compared with controls (p less than 0.001). The addition of cerebrospinal fluid drainage to aortofemoral shunting did not further improve neurologic outcome. Spinal cord blood flow measured with microspheres in the lumbar gray matter was significantly higher in the dogs with aortofemoral shunting (+/- cerebrospinal fluid drainage) as compared with those with cerebrospinal fluid drainage alone (p less than 0.05) or the controls (p less than 0.001). Aortofemoral shunting also prevented the development of acidosis and hyperglycemia. Loss or changes in amplitude and latency of motor-evoked potentials did not distinguish between the groups. Loss of somatosensory-evoked potentials had a high sensitivity (92%) but lower specificity (68%) in predicting neurologic injury, whereas loss of motor-evoked potentials had a high specificity (100%) but a very low sensitivity (16%). We conclude that cerebrospinal fluid drainage or aortofemoral shunting significantly improve spinal cord blood flow and neurologic outcome. The greatest increase in spinal cord blood flow was seen with aortofemoral shunting, which also prevented metabolic disturbances of reperfusion. Although the addition of cerebrospinal fluid drainage to aortofemoral shunting was the only group in which no neurologic injury occurred, this group did not have a significant improvement in outcome when compared with aortofemoral shunting alone. Spinal cord ischemia was more accurately detected with somatosensory-evoked potentials when aortofemoral shunting was used, whereas motor-evoked potentials recorded from the spinal cord were not sensitive enough to predict neurologic injury.     

Complications of cerebrospinal fluid drainage in thoracoabdominal aortic aneurysm repair

Spinal cord ischemia resulting in postoperative paraplegia is a devastating complication of thoracoabdominal aortic aneurysm repair, and has been attributed to many causes. To prevent spinal cord compartment syndrome, cerebrospinal fluid drainage has been used as an adjunct to thoracoabdominal aortic aneurysm repair, with procedure-related complications generally occurring infrequently. We present two case reports of serious complications from CSF drainage.     

Proinflammatory cytokines in cerebrospinal fluid in repair of thoracoabdominal aorta

BACKGROUND: Little is known about alterations of cytokine levels in cerebrospinal fluid (CSF) during thoracoabdominal aortic surgery. We measured perioperative CSF cytokine levels to determine their clinical significances. METHODS: Perioperative serum and CSF levels of cytokine were measured in 15 adult patients undergoing repair of the descending thoracic aorta (n = 4) or thoracoabdominal aorta (n = 11). All patients underwent prosthetic replacement and perioperative CSF drainage. Serum and CSF levels of tumor necrosis factor-alpha, Interleukin- (IL-) 1beta, IL-6, IL-8, IL-10, and IL-12 were measured before operation and at 0, 6, 12, 18, 24, 48, and 72 hours postoperatively using enzyme-linked immunosorbent assays. RESULTS: There were no hospital deaths, but 1 patient suffered paraplegia. Cerebrospinal fluid IL-8 levels peaked at immediately after operation (751.7 +/- 42.1 pg/mL versus preoperative levels, 54.9 +/- 24.6 pg/mL; p < 0.001), and the higher levels persisted for 72 hours. In contrast, serum IL-8 levels did not change and remained lower than CSF levels. The patient with paraplegia had the highest CSF IL-8 levels throughout the study period. Serum and CSF levels of tumor necrosis factor-alpha, IL-1beta, IL-6, and IL-12 did not significantly change. Serum and CSF levels of IL-10 were significantly elevated after operation compared with preoperative levels. In contrast to IL-8, serum IL-10 levels surpassed CSF levels. CONCLUSIONS: Cerebrospinal fluid IL-8 levels are significantly elevated in thoracoabdominal aortic operation, and may be the most sensitive to the inflammatory response in the ischemic spinal cord injury. Persistent elevation of CSF IL-8 levels may be predictive of further development of neurologic deficits, and a reduction of proinflammatory cytokine levels may be a beneficial effect of CSF drainage, but this requires further investigation.     

Tau protein in the cerebrospinal fluid is a marker of brain injury after aortic surgery

BACKGROUND: Tau is a protein localized primarily in neurons, especially in the axonal compartment. Cerebrospinal fluid tau levels are elevated in acute stroke and head traumas. The purpose of this study is to elucidate the alterations of cerebrospinal fluid tau levels in patients with or without neurologic complication after aortic surgery. METHODS: Twenty-eight patients undergoing descending thoracic (n = 8) or thoracoabdominal (n = 20) aortic surgery were enrolled. Cerebrospinal fluid tau levels were measured before operation and at seven time points up to the 72nd postoperative hour, and were compared with cerebrospinal fluid S100B levels. RESULTS: Two patients developed brain infarction, including the one with paraplegia. In these patients, 20-fold to 100-fold tau elevation was observed, but S100B elevation was less evident in the patient without paraplegia. Three other patients developed spinal cord injury. Additional three patients suffered from temporary neurologic dysfunction of the brain. Tau levels in the latter three patients showed tenfold elevation and were higher than those in the three patients with spinal cord injury or those in the patients without neurologic complication up to 24 postoperative hours. The S100B levels were also higher in the three patients with temporary neurologic dysfunction of the brain than in the patients without neurologic complication at the conclusion of surgery. From 6 to 24 postoperative hours, they were higher in the three patients with spinal cord injury than in the patients without neurologic complication. CONCLUSIONS: These preliminary results suggest that cerebrospinal fluid tau levels reflect brain injury. Because tau levels may separate the patients with temporary neurologic dysfunction, they may serve as a useful marker of brain injury.     

Descending thoracic aortic aneurysm: surgical approach and treatment using the adjuncts cerebrospinal fluid drainage and distal aortic perfusion

BACKGROUND: Neurologic deficit (paraplegia or paraparesis) remains a significant morbidity in the repair of descending thoracic aortic aneurysm. METHODS: Between February 1991 and February 2000, we operated on 182 patients for descending thoracic aortic aneurysm. For the purpose of this study-to identify the impact of the combined adjuncts distal aortic perfusion and cerebrospinal fluid (CSF) drainage on neurologic outcome-we selected the 148 of 182 nonemergent patients who had received conventional treatment (simple cross-clamping with or without adjuncts). The mean patient age was 61 years, and 49 of the 148 (33%) patients were women. Nine of the 148 patients (6%) had acute type B dissections. We compared the results of 105 of the 148 patients (71%) who received the combined adjuncts of CSF drainage and distal aortic perfusion with the remaining 43 (29%) patients who underwent repair using the simple cross-clamp with or without the addition of a single adjunct. RESULTS: Overall 30-day mortality was 13 of 148 patients (8.8%). Overall early neurologic deficit was 4 of 148 (2.7%): 1 of 105 (0.9%) patients who had received distal aortic perfusion and CSF drainage, versus 3 of 43 (7%) in all other patients (p < 0.04). CONCLUSIONS: In our practice the use of the combined adjuncts of CSF drainage and distal aortic perfusion has all but eliminated the incidence of immediate postoperative neurologic deficit in nonemergent patients with aneurysms of the descending thoracic aorta.     

Prevention and detection of spinal cord injury during thoracic and thoracoabdominal aortic repairs

BACKGROUND: Spinal cord injury is a most dreaded and unpredictable complication. In this study, based on our experimental results in dogs and early clinical results, we reviewed the incidence of paraplegia and the detection of spinal cord injury. METHODS: Eighty-two patients who underwent elective surgical repair of the descending thoracic and thoracoabdominal aorta over 17 years were subjects for this study. Sixty-two patients were male and 20 were female. Their mean age was 61.6 years (range, 17 to 81 years). Monitoring somatosensory evoked potentials (SEP) and measurement of mean distal aortic pressure and cerebrospinal fluid pressure were performed perioperatively. RESULTS: Sixty patients had no ischemic change in SEP. In 17 patients with significant ischemic changes of SEP, SEP recovered by increasing spinal cord perfusion pressure to more than 40 mm Hg. Two patients with complete loss of SEP experienced paraplegia. One patient had delayed paraplegia. CONCLUSIONS: These results strongly suggest that SEP, mean distal aortic pressure, cerebrospinal fluid pressure should be monitored during aortic cross-clamping. Maintaining spinal cord perfusion pressure at more than 40 mm Hg by increasing mean distal aortic pressure or withdrawal of cerebrospinal fluid is valuable for preventing paraplegia.     

Paraplegia following elective endovascular repair of abdominal aortic aneurysm: reversal with cerebrospinal fluid drainage.

Paraplegia secondary to spinal cord ischaemia is a rare but devastating complication of abdominal aortic aneurysm repair. We report a case of paraplegia following elective endovascular repair of an infrarenal aortic aneurysm. A cerebrospinal fluid (CSF) drain was immediately inserted and resulted in full neurological recovery. This case highlights the fact that endovascular techniques are prone to similar complications as open surgery, and the importance of prompt cerebrospinal fluid drainage in cases of spinal cord ischaemia.     

Somatosensory evoked potentials and spinal cord perfusion pressure are significant predictors of postoperative neurologic dysfunction

Paraplegia after thoracoabdominal aneurysm repair can occur in 3% to 40% of patients. This study investigated the efficacy of cerebrospinal fluid (CSF) drainage to protect the spinal cord during aortic cross-clamping (AXC) and the interrelationship between drainage, spinal cord perfusion pressure (SCPP), and changes in somatosensory evoked potentials (SEP) in a canine model of spinal cord ischemia. SCPP was defined as the mean distal aortic pressure minus the CSF pressure. In the experimental group, CSF was drained before AXC. SEP changes were quantitated as time to latency increase of 10% (L-10) and time to complete SEP loss. Drainage of CSF had no significant effect on the distal aortic pressure but significantly increased SCPP from 9.4 to 21.8 mm Hg and decreased the incidence of postoperative neurologic injury. Ischemic SEP changes were highly significant predictors of postoperative neurologic injury, occurring more than two times earlier in the paralyzed and paraparetic animals. Dogs without neurologic injury had significantly higher SCPP, delayed L-10 time, and delayed SEP loss.     

Intrathecal papaverine for the prevention of paraplegia after operation on the thoracic or thoracoabdominal aorta

Eleven patients undergoing operation on the descending or thoracoabdominal aorta were administered papaverine intrathecally in an attempt to protect the spinal cord from ischemic damage. Concurrently, 19 patients, also undergoing operation on the thoracic or thoracoabdominal aorta, were operated on with a variety of conventional techniques, including distal aortic perfusion, but were not given intrathecal papaverine. No signs of early neurologic injury developed in any of the patients in the intrathecal papaverine group, although delayed paraparesis developed in one of the patients (9%; 70% confidence limits = 1% to 28%). On the other hand, eight of 19 patients undergoing operation with conventional techniques had either lower extremity paraparesis or paraplegia postoperatively (42%; 70% confidence limits = 29% to 57%; p = 0.058). Intrathecal papaverine appeared to provide spinal cord protection during thoracic aortic operations, particularly during prolonged periods of aortic cross-clamping. Papaverine was not associated with increased risk and may be superior to other conventionally used modalities. We conclude that continued evaluation of this technique is justified.