Neurosurgical forum Without knowing the intentions of the neurosurgeon who implanted it, it would also be wrong to call it a misapplication of the device. Perhaps a more appropriate title for my letter would have been "Dangers Inherent in the On-Off Device for CSF Shunts." As Dr. Portnoy states in his letter and I stated in my original letter, this device should be used with caution. I would still recommend that the literature packaged with the on-off device state its opening pressure. The multipurpose valve does have a place in the neurosurgical armamentarium in the battle against hydrocephalus. Awareness of the dangers inherent in the use of this shunt will remind neurosurgeons to use the device in those patients for whom its features are specifically indicated. ARTHURM. GERBER,M.D. Toledo, Ohio

Microadenectomy or Microhypophysectomy T o THE EDITOR: I wish to comment on the recent article on transsphenoidal microhypophysectomy in acromegaly (U HS, Wilson CB, Tyrrell JB: Transsphenoidal microhypophysectomy in acromegaly. J Neurosurg 47.'840-852, December, 1977). The authors should be congratulated for this excellent article on the treatment of acromegaly using the open transsphenoidal approach and microsurgical technique. Since we introduced the method in early 1960, it is gratifying to encounter several other groups who are convinced of its superior effectiveness. I have only a minor critical comment concerning the use of the proper name for describing the surgical method. " M i c r o h y p o p h y s e c t o m y " refers to ablation of the normal pituitary gland, as used in the palliative treatment of advanced breast cancer or diabetic retinopathy. On the contrary, in the treatment of acromegaly, all effort is made to preserve the normal gland while only the tumor is selectively removed. Therefore the procedure should be called "microadenectomy." JULESHARD~, M.D. Montreal, Quebec

Ankylosing Spondylitis and Sciatica T o THE EDITOR: In a recent report (Bingham WF: The role of HLA B27 in the diagnosis and management of low-back pain 668

and sciatica. J Neurosurg 47:561-566, October, 1977), Bingham discussed the value of typing for H L A B27 in patients hospitalized with low-back pain and sciatica before using invasive diagnostic procedures. HLA B27, one of the histocompatibility antigens that participates in cell interactions concerned with immunity, is present in only 7% of Caucasians but has been found in 96% of patients with ankylosing spondylitis (AS). Since AS usually presents with low-back pain, as well as sciatica in 10%, it can mimic the syndrome of ruptured lumbar intervertebral disc. Thus, tissue typing for HLA B27 would seem to be a good differentiator. However, H L A B27 typing alone is not sufficient; only 20% of Caucasians with HLA B27 ever develop definite AS. It is as though AS is the result of an altered immune response of B27-positive individuals to infection (venereal?) by an unknown organism. Because 20% of the population often has lowback pain, back pain in a B27-positive patient is equally likely to be due to some other condition as to AS. Furthermore, since AS occurs in, at most, 1.4% of Caucasians (20% of 7%), most patients with back pain do not have AS, and B27 screening would thus be of low yield. Is there a subset of patients in whom H L A B27 typing would frequently prevent unnecessary myelography? Patients with neurological signs or a crossed sciatic sign would be excluded from this subset, which would contain a large proportion of patients with lowback pain only, especially if associated with morning stiffness. Alternating sciatica, systemic signs such as fever, weight loss, anemia, and elevated sedimentation rate also increase the suspicion of AS. Suspicion of sacroiliitis in x-ray studies might also call for B27 typing. So far, the primary value of HLA B27 typing has been to increase our awareness of AS by showing that the disease is 100 times more prevalent than previously suspected and occurs equally in men and women. The association of H L A B27 and AS is significantly lower in black Americans. With increasing awareness, undiagnosed cases have been found by identifying previously unreported changes in the sacroiliac joints, and we should now pay more attention to this area when reading spine films. Also, isotope bone scan may be positive before sacroiliitis is visible

J. Neurosurg. / Volume 48 / April, 1978

Neurosurgical forum roentgenographically, but only in patients with an elevated sedimentation rate. Dr. Bingham is to be commended for bringing this subject to the attention of neurosurgeons. The article by Calin and Fries ~ is also recommended to physicians who treat low-back pain. W. ROBERTHUDGINS,M.D. Dallas, Texas Reference

1. Calin A, Fries JF: Striking prevalence of ankylosing spondylitis in "healthy" W27 positive males and females. N Engl J Med 293:835-839, 1975 RESPONSE: Doctor Hudgins' comments regarding the significance of H L A B27 testing are much appreciated. I agree with his implication that not all patients with lowback pain require B27 screening and that physicians should be selective in ordering the test. Unfortunately, I cannot be more precise. The subset to which he refers would appear to be those patients who have enough suspicious historical, physical, laboratory, and radiological findings to warrant testing. Even the patient with an enormous lumbosacral disc extrusion frequently has a father or brother with similar complaints, such as low-back stiffness on awakening or one fuzzy sacroiliac joint. From a totally pragmatic standpoint, B27 testing is important because the diagnosis of ankylosing spondylitis (AS) is so evasive. The presence of the antigen certainly does not es-

J. Neurosurg. / Volume 48 / April, 1978

tablish the diagnosis. It sounds a note of caution. It forces the clinician to consider this possibility more seriously. He may wish to initiate a therapeutic trial of anti-inflammatory medication (such as phenylbutazone, indomethacin, salicylates), or to obtain a formal consultation in rheumatology. Additional x-ray films of the sacroiliac joints, including tomography, may be indicated. A further trial of conservative management may even be warranted. If AS can be reasonably excluded after such a cautious review, he may confidently proceed with his original diagnostic and therapeutic plans. I might add that the patient who is found to be B27-positive should probably be informed of that fact and of its potential significance. If he harbors both a lumbar disc rupture and early AS, he may not derive the symptomatic relief from surgery that might otherwise be expected. Such cases no doubt account for a small percentage of discectomy failures. WILLIAMF. BINGHAM, M.D. La Crosse, Wisconsin

Basal Ganglia Germinoma and Dystonia: Erratum

We regret that, through a printer's error, in the article by Lins, et al. (Lins M M , McDonnell DE, Aschenbrener CA, et al: Extrapyramidal disorder with pineal germinoma. Case report. J Neurosurg 48:108-116, 1978), Figure 5 was printed upside down.

669

Ankylosing spondylitis and sciatica.

Neurosurgical forum Without knowing the intentions of the neurosurgeon who implanted it, it would also be wrong to call it a misapplication of the dev...
268KB Sizes 0 Downloads 0 Views