Reply to Dr Nash

Reply to Dr Nash

218 Letters to the Editor motor weakness which was considered to be fully compatible with a cauda equina lesion. I have also been aware of three sim...

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218

Letters to the Editor

motor weakness which was considered to be fully compatible with a cauda equina lesion. I have also been aware of three similar cases following root sleeve injections of local anaesthetic and steroid. I do not know the details of the first case, but have recently been asked to comment on a case with persisting neurological sequelae after injection at C3, with hemiparesis and sensory deficit, and a further patient with urinary incontinence following root sleeve injections unilaterally at L4, L5 and S1, although it is doubtful that this was due to the injection. The anatomy of the blood supply to the cord is well described. Dommisse et al. (1980) have performed anatomical dissection of 50 human cadavers. The cord is totally dependent on the three longitudinal arterial trunks, which run from the medulla to the conus medullaris. The anterior spinal artery overlies the median sulcus of the cord, and gives off anterior perforators that supply the cord. The paired posterolateral trunks are small and tortuous, being intertwined between the posterior rootlets. The posterior perforators penetrate the cord in the company of the nerve rootlets. Ligation of the anterior vessel distal to the artery of Adamkiewicz usually leads to paraplegia in the rhesus monkey. The medullary feeder arteries supply and maintain the long arterial trunks. These are variable in number and level of supply. They arise from the segmental arteries (which supply the segmental nerves, and arise at every segmental level). There are usually more than nine (two to 17) supplying the anterior and more than 15 (six to 25) supplying the posterior trunks. The artery of Adamkiewicz (arteria radicalis anterior magna) is the largest medullary feeder and occurs on the left side in 80% of cases between T7 and L4, especially T9–T11. The intervertebral foraminae are of critical value in the blood supply of the cord, as the feeder vessels pass through the foraminae alongside the nerve root. However, Dommisse does show that there are arteri-arterial anastomoses between the segmental intervertebral arteries in the thorax. They are potential sources of alternative supply to the cord. Dommisse proposed surgical guidelines to prevent postoperative paraplegia. He stated that neither cautery nor tight plugging nor heavy retraction should be applied to the intervertebral foramen, lest a single essential feeder vessel be destroyed. Two decades on, we should heed his advice, and treat the foramen with respect. Trauma to the feeding vessels from the introduction of needles to the foramen can produce vasospasm, and the potential for consequent cord ischaemia. We have an obligation to warn our patients of the risk, however small, of such a catastrophic complication when we perform such procedures.

References Brouwers PJAM, Kottink EJBL, Simon MAM, Prevo RL. A cervical anterior spinal artery syndrome after diagnostic blockade of the right C6nerve root. Pain 2001;91:397–399.

Dommisse GF. The arteries, arterioles, and capillaries of the spinal cord: surgical guidelines in the prevention of postoperative paraplegia. Ann R Coll Surg Engl 1980;62:369–376. Koning HM, Koster HG, Niemeijer PE. Ischaemic spinal cord lesion following percutaneous radiofrequency spinal rhizotomy. Pain 1991;45:161–166. Timothy Paul Nash a,b,* Walton Centre for Neurology and Neurosurgery, Lower Lane, Fazakerley, Liverpool L9 7LJ, UK b Department of Neuroscience, Pain Research Institute, University of Liverpool, Liverpool, UK a

* Tel.: 144-151-529-5749; fax: 144-151-529-5486. E-mail address: [email protected] (T.P. Nash).

PII: S0 304-3959(02 )00 005-2

Reply to Dr Nash We thank Dr Nash for his comments regarding our paper in which we describe a cervical anterior spinal artery syndrome after diagnostic blockade of the right C6-nerve root. Dr Nash adds a few interesting cases of medullary complications after injections into the intervertebral foraminae at different levels. He concludes that we have an obligation to warn our patients of the risk, however small, of such a catastrophic complication when we perform such procedures. A recent e-mail I received from an anaesthesiologist from the United States emphasizes this opinion. He mailed me the following message: “I do about 1500 blocks a year, this past week I performed a right C6 selective nerve root block under fluoroscopy using the same tunnel approach that you described, on a healthy 53-year-old male. Following the block (I used lidocaine 1%, 2 cm 3 and triamcinolon 40 mg) the patient sat up and stated that his arms felt weak and that he had difficulty catching his breath…. The second MRI showed a cord infarct consistent with the anterior spinal artery…. The procedure had gone smoothly”. In his second e-mail he wrote me that he had been notified that a suit had been filed. Considering our medicolegal-driven healthcare systems, I tend to agree with Dr Nash that, although there are very few detailed reports in literature of these kind of complications, we should warn our patients of the risk of cord infarction as an iatrogenic complication, when we perform such procedures. Paul J.A.M. Brouwers a,*, Ella J.B.L. Kottink a, Marc A.M. Simon b, Rik L. Prevo c a Department of Neurology, Medisch Spectrum Twente, P.O. Box 50.000, 7500 Enschede, The Netherlands

Letters to the Editor b

Department of Anaesthesiology, Medisch Spectrum Twente, Enschede, The Netherlands c Department of Neuroradiology, Medisch Spectrum Twente, Enschede, The Netherlands

* Corresponding author. Tel.: 131-534872000; fax: 131-534872882. E-mail address: [email protected] (J.A.M. Brouwers).

PII: S 0304-395 9(02)00006-4

Spiritual healing as a therapy of chronic pain: a randomized, clinical trial We read with great interest the randomized clinical trial by Abbot et al. (2001) that sought to assess the efficacy of spiritual healing in chronic pain. Measuring and treating chronic pain presents a true clinical challenge. The authors are to be commended for applying a rigorous scientific framework to the investigation of an alternative/complementary therapy of healing. In this study the primary outcome measure of efficacy was the McGill Pain Questionnaire (MPQ). Since its introduction as a novel and innovative instrument to quantify pain (Melzack, 1975), the MPQ has been used to measure pain for many conditions both acute and chronic. The responsiveness of the MPQ, specifically its ability to accurately detect change when it has occurred, has not been subjected to formal responsiveness studies. In the context of using the MPQ as a primary outcome measure in randomized controlled trials on pain treatment modalities the question is raised as to what constitutes a clinically meaningful change. Farrar et al. (2000) and Rowbotham (2001) have underscored this issue pointing out that determining and defining a clinically important change in level of pain is challenging and understudied. Abbot et al. defined an eightunit change in PRIT score as the level for analyzing significant change. We are interested in knowing how the authors chose this specific value and under what terms it was found to be clinically relevant. Pain is a multi-dimensional, complex, and subjective experience which makes evaluating it extremely challenging. The MPQ is based on three qualities of pain, namely sensory, affective, and evaluative dimensions. Formal studies on the validity of the MPQ, including factor analysis, have shown sensory and affective dimensions to be consistently demonstrated but have varied in their results suggesting between two and seven dimensions (Bailey and Davidson, 1976; Leavitt et al., 1978). This suggests that the dimensions of pain presented by the MPQ are not always clearly evident and raises the question of whether there are other dimensions of pain not considered in the construct/content of the MPQ. It is possible that a thera-

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peutic modality such as spiritual healing affects a different aspect of the pain experience that is not assessed by the MPQ. Using this argument, one needs to find a suitable measurement tool for the modality being tested or else suffer the consequences of lacking construct validity. In other words, if the effects of spiritual healing change pain in ways other than in the sensory, affective, or evaluative aspects, then it will not likely be detected except by chance. A third concern relates to the practice of comparing grouped mean pain scores. By combining the scores of those who improved after the intervention with those who did not or with those who worsened, it is possible that an effect among a significant proportion of responders could be missed (Farrar et al., 2000). Although the authors did note (Part I) that eight subjects in the treatment group and five in the control group experienced a greater than 50% reduction in pain, the statistical significance of this difference was not determined. Finally, in future studies we would suggest coupling other clinically relevant measures, such as use of analgesics and/ or pain-related physician visits, with the complementary scales used by the authors. We recognize the inherent difficulties in undertaking comprehensive evaluations of chronic pain, and look forward to future investigations on this interesting therapy.

References Abbot NC, Harkness EF, Stevinson C, Marshall FP, Conn DA, Ernst E. Spiritual healing as a therapy of chronic pain: a randomized, clinical trial. Pain 2001;91:79–89. Bailey CA, Davidson PO. The language of pain: intensity. Pain 1976;2:319–324. Farrar JT, Portenoy RK, Berlin JA, Kinman JL, Strom BL. Defining the clinically important difference in pain outcome measures. Pain 2000;88:287–294. Leavitt F, Garron DC, Whisler WW, Sheinkop MB. Affective and sensory dimensions of back pain. Pain 1978;4:273–281. Melzack R. The McGill pain questionnaire: major properties and scoring methods. Pain 1975;1:277–299. Rowbotham MC. What is a ‘clinically meaningful’ reduction in pain?. Pain 2001;94:131–132.

Worth Everett a,b,*, Faten Aberra c, Gregory Bisson d, Bruno Casanova e, Emmanuelle Pare´ e, Barbara Piasecki c a Department of Emergency Medicine; Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104-4283, USA b Department of Internal Medicine; Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104-4283, USA c Division of Gastroenterology, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104-4283, USA d Department of Infectious Diseases, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104-4283, USA

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