Variability in the Treatment of Acute Spinal Cord Injury in the United Kingdom: Results of a National Survey

Abstract

The aim of this study was to examine how traumatic spinal cord injury is managed in the United Kingdom via a questionnaire survey of all neurosurgical units. We contacted consultant neurosurgeons and neuroanesthetists in all neurosurgical centers that manage patients with acute spinal cord injury. Two clinical scenarios—of complete and incomplete cervical spinal cord injuries—were given to determine local treatment policies. There were 175 responders from the 33 centers (36% response rate). We ascertained neurosurgical views on urgency of transfer, timing of surgery, nature and aim of surgery, as well as neuroanesthetic views on type of anesthetic, essential intraoperative monitoring, drug treatment, and intensive care management. Approximately 70% of neurosurgeons will admit patients with incomplete spinal cord injury immediately, but only 40% will admit patients with complete spinal cord injury immediately. There is no consensus on the timing or even the role of surgery for incomplete or complete injuries. Most (96%) neuroanesthetists avoid anesthetics known to elevate intracranial pressure. What was deemed essential intraoperative monitoring, however, varied widely. Many (22%) neuroanesthetists do not routinely measure arterial blood pressure invasively, central venous pressure (85%), or cardiac output (94%) during surgery. There is no consensus among neuroanesthetists on the optimal levels of arterial blood pressure, or oxygen and carbon dioxide partial arterial pressure. We report wide variability among U.K. neurosurgeons and neuroanesthetists in their treatment of acute traumatic spinal cord injury. Our findings reflect the lack of Class 1 evidence that early surgical decompression and intensive medical management of patients with spinal cord injury improves neurological outcome.

Introduction

A bout 1000 people each year in the U.K. and 10–39 per million internationally, primarily healthy young men, suffer a traumatic spinal cord injury (Cripps et al., 2011) There is no treatment shown to improve neurological recovery after the injury, and even corticosteroids, which were initially thought to be beneficial (Bracken et al., 1997,1990), are no longer widely accepted (Sayer et al., 2006). Over a third (38%) of traumatic spinal cord injuries are complete (National spinal cord injury statistical centre, 2011). The outlook is bleak; of the patients with complete cervical cord injury on admission, 70% are left with a complete paralysis of arms and legs, 23% with severe weakness, and up to 20% remain ventilator-dependent (Marino et al., 2011). Of those with complete thoracic cord injuries, 82% have paralysis of both legs and are therefore wheelchair-bound without bladder or bowel control (Zariffa et al., 2011). The annual cost to the National Health Service (NHS) of patients with spinal cord injury is estimated at £0.5–1 billion (Cripps et al., 2011). In the U.S.A., the average lifetime cost of care for a 25-year-old paraplegic is $0.5 million, and for a 25-year-old tetraplegic $1.4 million.

In the U.K., most patients with acute traumatic spinal cord injury are managed by neurosurgeons and neuroanesthetists. The early surgical management of these patients is controversial. Some neurosurgeons advocate conservative management initially (Katoh and El Masry, 1994), arguing that the acutely injured cord is susceptible to further injury by multiple patient transfers, and changes in physiological parameters during anesthesia and surgery, as well as direct cord damage from surgical manipulation (El Masry, 1993). Some spinal injury units have adopted this conservative approach, but others prefer early bony decompression, arguing that this improves cord perfusion, thus potentially reducing secondary injury (Fehlings et al., 2010). Currently, there is no Class 1 evidence that early bony decompression and stabilization produces a better outcome than delayed surgery (Fehlings et al., 2010).

Acute spinal cord injury is accompanied by major changes in physiological parameters, including bradycardia and hypotension (Tuli et al., 2007) due to the loss of the sympathetic supply, as well as hypoxia and hypercapnia (Winslow and Rozovosky, 2003) from damage to the intercostal and phrenic nerves. There are uncertainties regarding the acute medical management of these patients with limited information on whether altering these parameters improves neurological outcome (Congress of Neurological Surgeons, 2002; Stevens et al., 2003). The effect of other factors on outcome after traumatic spinal cord injury in humans is also unknown, such as the type and dose of anesthetic drugs used during surgery.

In contrast to the management of traumatic spinal cord injuries, the management of brain injuries is more clearly defined. There are established medical interventions for brain injury to admission to a neurosurgical intensive care unit (Patel et al., 2002). For the treatment of moderate and severe head injuries, measurement of intracranial pressure is key. Although still under some debate, there are accepted measures to optimize intracranial pressure, including sedation, normocapnea, mannitol, hypertonic saline, ventricular drainage, and ultimately, surgical decompression. There is no equivalent for traumatic spinal cord injuries.

In view of the controversies in the management of spinal cord injury, we explored how patients with acute spinal cord injuries are cared for in the U.K. Using questionnaires, we obtained the views of consultant neurosurgeons throughout the country regarding the surgical management and consultant neuroanesthetists regarding the medical management.

Methods

Neurosurgical survey

Neurosurgeons were presented with two clinical scenarios, of a complete and an incomplete acute traumatic cervical spinal cord injury at C6–C7 in a 40-year-old. Prior approval was obtained from the Academic Committee of the Society of British Neurological Surgeons (SBNS), and the survey was disseminated online and via post. The questions asked were to assess the requirements of pre- and/or post-operative magnetic resonance imaging (MRI), timing of transfer to the neurosurgical unit, routine medical management, timing of surgery, and the aim of surgery. The neurosurgical survey is in Appendix 1.

Neuroanesthetic survey

Neuroanesthetists were asked questions about the management of acute traumatic spinal cord injury in general. Prior approval was obtained from the Neuroanaesthetic Society of Great Britain and Ireland (NASGBI). We asked about the experience of the anesthetist and their preferences regarding anesthesia and intraoperative monitoring, control of physiological parameters, and use of glucocorticoids, as well as management in the intensive care unit in the week following acute traumatic spinal cord injury. The neuroanesthetic survey is in Appendix 2.

Neurosurgeon participants

All fully registered members of the Society of British Neurological Surgeons were invited to participate (i.e., consultant neurosurgeons across the country). The total number is 233 from 33 units. Participants were given 3 months to either complete the postal survey or online link, following which the survey was closed to responses. We received 79 responses (34% response rate) from all of the 33 units.

Neuroanesthetist participants

All 257 fully-registered members of the NASGBI were invited to participate (i.e., consultant neuroanesthetists) via the NASGBI council. Participants were given a total of 3 months to respond. We received 96 responses (37% response rate).

Statistical analysis

The McNemar chi-square test was used to compare the matched responses for dichotomous variables on the incomplete and complete scenarios. When variables had three or more possible responses, the matched responses on the incomplete and complete scenarios were compared using the McNemar-Bowker test of symmetry. Both tests investigated for symmetry around paired responses; that is, if responses differed for incomplete and complete scenarios, whether this disagreement was greater for some categories of responses than others. If the frequency of disagreements was equal, the changes balanced each other out and there was no significant change in the way the incomplete and complete scenarios scored overall in the sample. The test was statistically significant if the frequency of disagreements was unequal. The critical level of significance was p<0.05.

Results

Neurosurgical survey

We asked whether neurosurgeons image the spinal cord with MRI, rather than just with computed tomography (CT), after spinal cord injury. For incomplete injuries, 90% (64/71) of neurosurgeons request a preoperative MRI scan, and 39% (28/71) a postoperative MRI scan. For complete injuries, 79% (54/68) of neurosurgeons request a preoperative MRI scan, and 28% (19/68) a post-operative MRI scan. The main reasons for requesting an MRI scan were to assess for disc protrusion or hematoma or other soft-tissue injury (42%), to assess the degree of cord injury (25%), to confirm the adequacy of the surgical decompression (15%), and for prognosis (9%). A fifth of neurosurgeons would only request an MRI if there is clinical deterioration.

We then assessed how urgently neurosurgeons treat patients with cord injury, which includes how urgently they admit and how urgently they operate. Seventy percent (55/79) admit incomplete injuries immediately, but only 24% (17/71) operate within 4 h of arrival. Forty-two percent (32/76) admit complete injuries immediately, but only 12% (8/68) operate within 4 h of arrival. We also established the main aim of surgery. For incomplete spinal cord injury, 20% (14/71) aimed to stabilize bone, 11% (8/71) to decompress the dura, 66% (47/71) to stabilize bone and decompress dura, and 3% (2/71) do not operate. For complete spinal cord injury, 43% (29/68) aimed to stabilize bone, 3% (2/68) to decompress the dura, 47% (32/68), to stabilize bone and decompress the dura, and 7% (5/68) do not operate. Our data indicate considerable variability in the timing of admission and surgery and the aim of surgery.

We determined neurosurgical opinions on best medical management. We evaluated treatments that reduce elevated intracranial pressure, but with the exception of steroids, have not been evaluated in spinal cord injury. A fifth (14/71) of neurosurgeons recommend glucocorticoids, 21% (15/71) maintain arterial Pco ₂ within normal limits, and only 3% (2/71) consider mannitol or hypertonic saline. Table 1 summarizes the neurosurgical opinions regarding MRI scans, and timing of admission and surgery, as well as medical management for incomplete and complete cervical cord injuries.

Table 1.

Neurosurgical Survey Responses

	Incomplete n (%)	Complete n (%)
Timing of admission	n=79	n=76
Immediately (<4 h)	55 (70)	32 (42)
Within 4–24 h	14 (18)	23 (30)
Within 1–4 days	2 (3)	11 (14)
Do not admit	8 (10)	8 (11)
Not specified	0	2 (3)
Routine MRI	n=71	n=68
Pre-op “yes”	64 (90)	54 (79)
Post-op “yes”	28 (39)	19 (28)
Routine medical management	n=71	n=68
Oxygen	62 (87)	56 (82)
Nasogastric tube to prevent aspiration	36 (51)	35 (51)
Deep vein thrombosis prophylaxis	59 (83)	54 (79)
Glucocorticoids	14 (20)	11 (16)
Mannitol	1 (1)	0
Hypertonic saline	1 (1)	0
Control of blood pressure	62 (87)	56 (82)
Control of arterial pCO₂	15 (21)	14 (21)
Temperature regulation	33 (46)	34 (50)
Timing of surgery	n=71	n=68
Immediately	17 (24)	8 (12)
Emergency List (4–12 h)	26 (37)	12 (18)
Elective list (12–72 h)	19 (27)	28 (41)
Delayed (>72 h)	6 (8)	13 (19)
Other	3 (4)	7 (10)
Aim of surgery	n=71	n=68
Bony stabilization±- instrumentation	14 (20)	29 (43)
Bony decompression of the theca	8 (11)	2 (3)
Both stabilization and decompression	47 (66)	32 (47)
Durotomy±patching	0	0
Not specified	2 (3)	5 (7)

Statistical analysis revealed significant differences in the management of complete versus incomplete spinal cord injuries. Neurosurgeons were less likely to request pre-operative or post-operative MRI for complete versus incomplete injuries, but their medical management was similar (Appendix 3). There was significantly more delay in admitting and operating on completely versus incompletely cord-injured patients (Appendix 4). Surgery was significantly more conservative for complete versus incomplete injuries; the primary aim of surgery was stabilization only for complete injuries, compared with decompression and stabilization for incomplete injuries (Appendix 5).

Neuroanesthetic survey

We determined the preferred anesthetic agent and fresh gas mixture in surgery. The most popular were desflurane, target controlled infusion (TCI) propofol plus remifentanil, and sevoflurane, for 35% (17/49), 33% (16/49), and 27% (13/49) of neuroanesthetists, respectively. These agents are also preferred in brain injury (Coles et al., 2000; Engelhard and Werner, 2006). Most (96%, 47/49) neuroanesthetists avoid nitrous oxide, which has been shown to elevate intracranial pressure (Henriksen and Jorgensen, 1973). Our data suggest that patients with cord injury are anesthetized similarly to those with brain injury.

We then asked about intraoperative monitoring. About 15% (7/48) always measure central venous pressure, 78% (38/49) always measure arterial blood pressure invasively, and 6% (3/48) always use non-invasive cardiac output monitoring. Arterial Pco ₂ and Po ₂ are kept between 4.0 and 5.0 and >10 kPa, respectively, by over 96% neuroanesthetists. We also assessed intraoperative cord monitoring. Somatosensory and motor-evoked potentials were always used in only 6% (3/48) and 0%, respectively. Overall, compared with intraoperative monitoring for brain injury (Patel et al., 2002), the monitoring for spinal cord injury is more limited.

We assessed whether, in the intensive care unit, neuroanesthetists manage spinal cord injury similarly to brain injury. Only 3% (1/39) considered mannitol or hypertonic saline after cord injury. No one advocated hypothermia. Most (92%, 35/38) maintained arterial Pco ₂ and Po ₂ within the normal range, 4.0–5.0 and >10 kPa, respectively. There was uncertainty about optimal mean arterial pressure; 54% (21/39) aimed for ≥80 mm Hg, with the use of inotropes if required. About a fifth (8/39) recommend methylprednisolone after the injury. Our findings suggest that the medical management of spinal cord injury does not aim to optimize cord perfusion or oxygenation. Table 2 summarizes the neuroanesthetic survey of anesthetic agents and intraoperative monitoring, as well as the intensive care management.

Table 2.

Neuroanaesthetic survey responses

	Number (%) of responders
Intraoperative monitoring [n]	Sometimes		Always	Never
Temperature [49]	8 (16)		41 (84)	0
Central venous pressure [48]	36 (75)		7 (15)	5 (10)
Urine output [49)	12 (24)		37 (76)	0
Peripheral nerve stimulator [49]	26 (53)		15 (31)	8 (16)
Bispectral index [48)	10 (21)		1 (2)	37 (77)
Non invasive cardiac output [48]	17 (35)		3 (6)	28 (58)
Invasive arterial blood pressure [49]	11 (22)		38 (78)	0
Somatosensory evoked response [48]	10 (21)		3 (6)	35 (73)
Motor evoked response [47]	10 (21)		0	37 (79)
Preferred anaesthetic technique
Sevoflurane			13 (26)
Isoflurane			2 (4)
Desflurane			17 (35)
TCI propofol			1 (2)
TCI propofol + remifentanil			16 (33)
Preferred fresh gas mix
O2/N2O			2 (4)
O2/Air			47 (96)
Positive end expiratory pressure?
Yes			23 (47)
No			26 (53)
Preferred physiological parameters	< 4 kPa	4–4.4 kPa	4.5–5.0 kPa	> 5.0 kPa
Arterial pCO₂	0	16 (33)	31 (63)	2 (4)
Arterial pO₂	< 10 kPa		10–12 kPa	> 12 kPa
	0		9 (18)	40 (82)
	>/ = 60mmHg	>/ = 80mmHg	+/- 20% normal	Controlled hypotension
Invasive arterial blood pressure	12 (24)	20 (41)	17 (35)	0
Intensive care management [n]
Mannitol [39]			1 (3)
Hypertonic saline [39]			1 (3)
Temperature regulation [39]			26 (67)
	>/ = 60mmHg	>/ = 80mmHg	+/- 20% normal	No active control
Arterial blood pressure control (inotropes if required)	9 (23)	21 (54)	7 (18)	2 (5)
If intubated:	< 4 kPa	4–4.4 kPa	4.5–5.0 kPa	> 5.0 kPa
Control pCO₂	0	6 (16)	29 (76)	3 (8)
	< 10 kPa		10–12 kPa	> 12 kPa
Control pO₂	1 (3)		11 (29)	26 (68)
High dose methylprednisolone	Within 8 hours		Within 24 hours	Not recommended
	4 (10)		4 (10)	31 (79)

Discussion

Our survey revealed that the treatment of traumatic spinal cord injuries by U.K. neurosurgeons and neuroanesthetists is highly variable. To the best of our knowledge this is the first study of its kind in the U.K. Overall, U.K. neurosurgeons are more conservative than their international colleagues in advocating early decompression. A survey by Fehlings and associates revealed that ≥85% of international neurosurgeons, primarily from America and Europe (not the U.K.), preferred to decompress the spinal cord within 24 h of the injury, regardless of complete versus incomplete cord damage (Fehlings et al., 2010). Only 29% of U.K. neurosurgeons decompress the cord within 24 h for complete and 61% for incomplete injuries. Our neuroanesthetic survey is unique and cannot be compared to the study by Fehlings and associates, who did not collect data on the medical management of patients with spinal cord injury.

Intuitively, early decompression should improve outcome; several animal experiments using rats (Dimar et al., 1999) and dogs (Carlson et al., 2003; Delamarter et al., 1995; Rabinowitz et al., 2008) confirm this. However, there is evidence from non-randomized trials (Ng et al., 1999; Pointillart et al., 2000; Vaccaro et al., 1997; Vale et al., 1997), case series (Botel et al., 1997; McKinley et al., 2004; Petitjean et al., 1995), and retrospective studies (Tator et al., 1999) that early decompression does not improve neurological outcome after spinal cord injury in humans. A major problem with the human data is the variability of the medical management. Failure to correct hypotension, hypoxia, hypercapnea, and hyperglycemia or fever may have confounded any benefits of decompression in these studies. To date there are no published data from randomized controlled trials comparing neurological outcome after early versus delayed surgical decompression in patients with optimized medical management. These issues may explain the variability in the surgical management of acute traumatic spinal cord injury, and we advocate that any further trials assessing timing of surgery should standardize medical management to remove any confounding factors.

The variability in anesthetic management of spinal cord injury is also explained by the lack of clear evidence. Although spinal cord pressure is not measured after a cord injury to guide management, our survey suggests that many U.K. neuroanesthetists assume that the injured spinal cord responds in the same way as the injured brain. Most (96%) anesthetize patients with spinal cord injury in the same way that they anesthetize patients with brain injury. However, intraoperative monitoring of patients with acute traumatic spinal cord injury is more limited, and their intensive care management does not follow the same principles as those used for brain injury (i.e., optimizing cord perfusion pressure and oxygenation). We believe this is deficient and may confound secondary injury.

Novel principles in spinal cord injury

By comparing the management of brain versus spinal cord injury, we recommend strategies (not currently used) that may improve neurological outcome after cord injury.

1. After brain injury, high intracranial pressure causes brain ischemia, herniation, and ultimately death (Patel et al., 2002). Therefore, intracranial pressure is measured and reduced. Spinal cord pressure at the site of injury is not measured after spinal cord injury, and it is thus impossible to evaluate the effects of anesthesia, early surgery, arterial blood pressure, and blood gases after spinal cord injury. We recommend developing a method to measure intrathecal spinal cord pressure at the site of injury.

2. Decompressive craniectomy for brain injury involves removing bone and opening the dura (Cooper et al., 2011; Jaeger et al., 2003). Bony decompression without dural opening is inadequate because intracranial pressure remains high. Decompressive surgery for spinal cord injury involves bony decompression and realignment without dural opening. Therefore, the spinal cord pressure probably remains high after spinal decompression. Durotomy and duraplasty in animal models have been shown to improve functional outcome (Smith et al., 2010). We recommend evaluating bony decompression plus duraplasty rather than bony decompression alone after spinal cord injury.

3. After severe brain injury we perform repeated CT scans to determine whether the brain is compressed. CT scans are inadequate for viewing the spinal cord; MRI scans are required instead. Our survey revealed that MRI scans are not routinely performed before or after spinal surgery. We recommend performing repeated MRI scans to evaluate spinal cord edema, dural compression, and the effect of treatments.

4. The treatment of spinal cord injury differs from the treatment of brain injury. In brain injury the bony damage is often ignored and attention is focused on preserving brain tissue. In spinal injury the spinal cord is often ignored and attention is focused at bony fixation. We recommend giving more emphasis on spinal cord perfusion and reducing secondary injury, rather than focusing on the bony injury alone.

Conclusions

The surgical and medical management of acute spinal cord injuries in the U.K. is variable. U.K. neurosurgeons treat traumatic spinal cord injuries more conservatively than international neurosurgeons. Our survey highlights the need for further research in the early management of spinal cord injury, including developing a method to measure spinal cord pressure and evaluating duraplasty, in addition to bony decompression, performing serial MRI scans, and placing the emphasis on reducing secondary neurological injury rather than fixing bone.

Footnotes

Acknowledgments

This work was funded by the Neurosciences Research Foundation (NRF) and the U.K. Spinal Cord Injury Research Network (UKSCIRN). The NRF and UKSCIRN played no role in study design, collection, analysis, interpretation of data, or writing of the report, or the decision to submit the article for publication. There is full independence of the researchers from the funders.

Author Disclosure Statement

No competing financial interests exist.

Appendix

(If yes, please complete the rest of the survey)

(If no, please go to question 11)

2. How many cases of acute spinal cord injury (within the first week) have you anaesthetized for spinal fixation* surgery in the year?

3. For patients that need surgery for spinal fixation* during the first week after an acute spinal cord injury, which of the following do you consider as essential monitoring?

4. During surgery for spinal fixation* of acute spinal cord injury do you use SSEPs or MEPs (please tick):

5. Your preferred anaesthetic technique for patients that present for spinal fixation* after acute spinal cord injury includes:

6. Your preferred fresh gas mixture for patients that present for spinal fixation* surgery is:

7. In this group of patients, during surgery do you maintain Pco ₂ within:

8. In this group of patients, during surgery do you maintain Po ₂ within:

9. Do you usually use PEEP?

10. During surgery for spinal fixation* within the first week after isolated spinal cord injury, what level do you maintain arterial blood pressure at?

11. As a Neuroanaesthetist do you look after patients in Intensive care?

(If Yes, please complete the rest of the survey), (If No, survey ends)

Which of the following would you consider as routine medical management for the acute phase (first week) of isolated traumatic spinal cord injury patients?

12. Mannitol?

13. Hypertonic saline?

14. Temperature regulation?

15. Active arterial blood pressure control (use of inotropes if needed)?

16. If intubated, control of Pco ₂?

17. If intubated, control of Po ₂?

18. What is your recommended use of high-dose methylprednisolone?

(i.e., 30 mg/kg bolus, 5.4 mg/kg/h for 24 h)

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