Authors' objectives:

The primary aim of this review was to provide a brief descriptive summary review of the literature on arachnoiditis and to synthesize available information to address the following topics:

- the available published literature in peer reviewed journals - the nature and etiology of arachnoiditis - the characteristics of diagnosis - the prevalence and incidence of arachnoiditis - the prognosis, treatment, prevention and future outlook of the condition - the public health concern in New Zealand.

Authors' recommendations: - Arachnoiditis was variously described in radiology, experimental and pathology literature. Differing terminology has been used and has led to confusion over what should be termed arachnoiditis. It is a non-specific inflammatory condition involving the leptomeninges and intrathecal neural elements. Three distinct entities were generally recognised arachnoidal adhesions, adhesive arachnoiditis and calcific arachnoiditis. The term in the literature used for more clinically obvious and symptomatic forms was usually chronic adhesive arachnoiditis. There was varied opinion over whether or not rarer and more extreme forms were the same disease or distinct entities. - Early cases of arachnoiditis were mainly a complication of infection. Etiology today may be of iatrogenic origin through complications arising from the treatment of lower back pain. Patients often had a history of a pre-existing back condition and had undergone multiple myelograms and multiple surgeries. It was impossible to determine the single causative event in most patients, and there was a need for definitive evidence on the etiology of the condition. The relative importance of these etiological factors in the future was largely speculative. - Direct surgical inspection and radiology provided objective evidence of arachnoiditis. Newer, non-invasive radiological technology allowed for a greater degree of anatomical detail of the spinal meninges and surrounding structures. Three distinct anatomical appearances were recognised clumps of adherent nerve roots residing centrally in the thecal sac, nerve roots residing peripherally to the meninges giving an empty sac appearance, and soft tissue mass replacing the sub arachnoid space. Dependence on MRI or CT alone to detect abnormalities could result in inappropriate clinical evaluation and intervention. - Attempts to correlate clinical signs and symptoms with radiological findings of arachnoiditis produced variable results. The origin, type, location and distribution of symptoms in arachnoiditis patients was often atypical. Chronic and severe back and/or lower extremity/leg pain was the most common symptom. Clinical history typically began with presentation for back injury and pain followed by clinical investigation, including multiple myelograms and surgery laminectomy (often multiple) and sometimes spinal fusion. Underlying diseases such as meningitis, recent herniated disc and spinal stenosis might all overlap with arachnoiditis. - It was not possible to calculate the actual population-based incidence or prevalence of arachnoiditis in any form as the clinical data was not available. Estimates in the literature were anecdotal and variable and tended to indicate that clinically significant arachnoiditis was a rare event. The complete reliance on clinical experience coupled with the conditions rarity would seem to preclude it from demographic study. - There is scarcity of literature dealing with the prognosis of arachnoiditis. This indicated that the prognosis of the condition was not strongly progressive nor improvement evident in most cases. Prognosis was complicated by the variable onset and spectrum of symptoms, difficulties in diagnosis and treatment, other underlying spinal pathologies and the ageing process. - Arachnoiditis is a complex neurogenic pain condition and the exact relationship between anatomical arachnoiditis and pain has not been clearly documented. Much of the literature on treatment was related to chronic non-cancer pain management. These study populations included a wide variety of diagnoses. Therapy for arachnoiditis was palliative as it tends to relieve some symptoms, provide pain relief and give assistance with functional impairment but in most cases does not cure. A multidisciplinary regimen of pain management treatments was recommended. - Well designed clinical trials on the efficacy and safety of steroid injections and infusions are needed to better determine the benefits and hazards of their therapeutic role. Spinal cord stimulation devices provided pain reduction in some arachnoiditis cases but there was remaining uncertainty over the benefits and long-term results of these treatments. Surgical intervention is reserved for carefully selected patients but remains controversial given its surgically challenging nature and the potential benefits and risks of such treatment. - It is not clear how coordinated and systematic research into arachnoiditis will proceed given the relative rarity of the condition, the anecdotal nature of the literature and unresolved controversies. Support groups and clinicians working in the area will remain an important impetus to future research. Prevention will be an important aspect of health strategies to address this condition given the recognised etiology which may have iatrogenic origins, particularly the prevention of post-operative and post-injection complications in patients through reliance upon evidence-based clinical guidelines and conservative multidisciplinary therapies.

Authors' methods: Systematic review

Project Status: Completed

URL for project: http://nzhta.chmeds.ac.nz/publications.htm

Year Published: 2001

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: New Zealand

Organisation Name: New Zealand Health Technology Assessment

Contact Address: Department of Public Health and General Practice, Christchurch School of Medicine and Health Sciences, University of Otago, P.O. Box 4345, Christchurch, New Zealand. Tel: +64 3 364 1145; Fax: +64 3 364 1152;

Contact Name: nzhta@chmeds.ac.nz

Contact Email: nzhta@chmeds.ac.nz

Copyright: New Zealand Health Technology Assessment (NZHTA)