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Three Part Question

In [adult patients with traumatic spinal cord injury] does [hyperbaric oxygen therapy] lead to [improved neurological benefit and outcome]

Clinical Scenario

A 36 year old motorcyclist sustained an isolated cervical spinal cord injury at C5/6 level discovered on MRI after falling off his motorcycle in a road traffic collision. You wondered whether hyperbaric oxygen therapy may be a useful treatment to improve his neurological outcome.

Search Strategy

A multi-field specific search was performed using the Ovid MEDLINE(R) database 1950 to April Week 1 2010, with the search terms below; The search was limited to English Language and Human.

(((HBO or HBOT or hyperbaric oxygen or hyperbaric oxygenation or hyperbaric oxygen therapy) and spinal cord injury) or spinal cord trauma).af. (303)
limit 1 to (english language and humans) (104)

Search Outcome

Ovid MEDLINE(R) database 1950 to April Week 1 2010 using a specific multi-field search returned 104 publications in total, 2 original journal articles were relevant.
Cochrane Library database using a sensitive search term returned 23 reviews in total, 1 review was found to be relevant.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Gamache et al. 1981 USA	ALL patients admitted for CNS spinal injury included. Hyperbaric treatment commenced <12hrs for Complete cord lesions and <24hrs for Incomplete cord lesion s 25 Patients received protocol guided hyperbaric treatment after standardised treatment: IV methylprednisolone 125mg IV Date: Jul 1977 to Dec 1978 13 patients were treated for 90-120mins at 2.5atm O2 every 2hrs x4, then every 6hrs x4 12 patients were treated for 90mins at 2.0atm O2 every 4hrs x3, then BD until improvement ceased.	Prospective, Non-randomised, non, case-controlled non-blinded comparison therapeutic trial using standardised protocol.	Initial level of motor function recorded and scored out of 100 (as normal)	Pre-HBOT score 32 compared to 36 post HBOT (P>0.10)	No power calculations and small sample size Non-randomised sample No case control group for objective comparison Lacking diagnosis criteria Non-blinded study subject to bias Confounders not considered i.e. variation of diagnosis Statistical data lacking
			Motor score repeated at discharge after hyperbaric treatment.	4 patient reported significant improvement (all had partial cord lesions) (no significant difference)
			Data compared to pre-collected non-hyperbaric treated patient data at 4 and 12 months.	21 reported no clinical difference
Asamoto et al. 2000 Japan	Selection of 34 patients from 114 patients with cervical spinal cord injury, who sustained hyperextension spinal cord injury with no bone damage and no previous history of vertebral or cord disease were selected. Date: June 1994 – April 1999. 13 patients received standardised HBOT protocol: 2.0atm O2 OD x 10days, started <24hrs of onset of disease. 21 patients received standard non-HBOT.	Retrospective, non-randomised, non-blinded case controlled observational therapeutic trial	Admission Neurological Cervical Spine Scale (NCSS) and mean rate (%) of improvement were compared between HBO and non-HBO group.	Improvement rate: In HBO group: Range from 100%-27.3%, with mean value 75.2% In non-HBO group: Range from 100%-25.0% with mean value 65.1%	No power calculations and small sample size Lacking detailed diagnostic method used. Non-randomised sample Non-blinded study subject to bias Actual statistical analysis not fully disclosed No mention of the time period between initial and outcome neurological analysis at follow up.
Ishihara et al. 1997 Japan	41 patients diagnosed with cervical myelopathy were treated with HBOT (2.5atm O2 for 1 hour) prior to planned elective neurosurgery. 18 – cervic al spondylotic myelopathy 17 – ossification of the posterior longitudinal ligament 6 – intervertebral disc herniation	Prospective non randomised, single-blinded, non-case controlled diagnostic trial	Pre-operative Japanese Orthopaedic Association (JOA) Score were recorded and the duration of neurological improvement observed in HBOT were categoried into 4 groups (excellent, good, fair, poor). The post operative JOA score at final follow up were then correlated to improvement observed in HBOT.	Recovery rate of JOA score: • Excellent group 75.2±20.8% • Good group: 78.1±17.0% • Fair group: 66.7±21.9% • Poor group: 31.7±16.4% Correlation between HBO effect and recovery rate of JOA score after surgery P=<0.0001 HBO can be employed to assess the chance of recovery of spinal cord function after surgical decompression	No power calculations and small sample size No control group for comparisons Non-randomised sample Not truly blinded study as assessor knew of HBOT involvement Diagnostic trial only

Comment(s)

Since the introduction of hyperbaric oxygen therapy (HBOT) in the 1960s, particular interests have been noted in its apparent usefulness of HBOT in improving recovery of injured neuronal tissues. Recent evidence evaluated in a 2009 Cochrane review has highlighted potential positive effect of HBOT in reducing the risk of death in patients suffering from acute traumatic brain injury; however it has not recommended the routine use of HBOT until further good quality outcome data is published. Much of the scientific evidence studying the potential mechanisms of HBOT in acute spinal cord injuries have been modelled from animal studies, and there is currently a chiasm of good quality clinical data from large randomised controlled trials correlating the multitude of animal study data to actual clinical outcome. From the limited available data studied in this review, there appears to be a consensus that HBOT is of limited therapeutic use in the recovery of permanently damaged neuronal cells, but its usefulness may lie within its potential ability to limit secondary neuronal cell death by reducing risk of cord oedema development through induction of vasoconstriction, whilst maintaining adequate oxygenation to neuronal tissues. The subsequent benefit of its ability to prevent secondary ischaemia from cord oedema development may be explained by the stabilisation of neuronal cellular activity and mitochondrial integrity, thus preventing apoptosis activation. Although the overall effectiveness of HBOT in acute spinal cord injury may appear to be limited to cord damage limitation, this potential positive effect may well be useful in patients who sustain Spinal Cord Injury Without Radiological Abnormalities (SCIWORA). When the diagnosis of SCIWORA is suspected after full radiological plain film and CT imaging, an MRI is recommended to exclude compressive lesions of the cord or roots or ligamentous disruption that might warrant surgical intervention (AANS). In confirmed cases of SCIWORA where there is no subluxation or malalignment injuries, the mainstay of treatment has been limited to lengthy immobilization and avoidance of activity that may lead to either exacerbation of the present injury or increase the potential for recurrent injury (AANS). With the proposed mechanism of neuro-protection with HBOT discussed above, HBOT may be effective in limiting secondary neuronal cell death in patients diagnosed with SCIWORA. Future good quality randomised controlled trial into the effectiveness of HBOT in the treatment of acute spinal cord injury may be indicated in the potential development of a new treatment modality for patients diagnosed with SCIWORA. However, based on current evaluation of available evidence, there is a lack of good quality evidence correlating scientific knowledge and clinical outcome to support the definitive clinical use of HBOT in acute spinal cord injury.

Clinical Bottom Line

Based on current evaluation of available evidence, there is a lack of good quality evidence correlating scientific knowledge and clinical outcome to support the definitive clinical use of HBOT in acute spinal cord injury.

References

1. Gamache et al. The Clinical Application of Hyperbaric Oxygen Therapy in Spinal Cord Injury: A preliminary report Surgical Neurology Vol. 15 (2) Feb 1981 p85-87
2. Asamoto et al. Hyperbaric oxygen (HBO) therapy for acute traumatic cervical spinal cord injury Spinal Cord (2000) 38, p538-540
3. Ishihara et al. Prediction of the surgical outcome for the treatment of cervical myelopathy by using hyperbaric oxygen therapy Spinal Cord (1997) 35, 763-767