692

HBV may be involved in the immunopathogenesis in some casesof IgA nephropathy in endemic areas.M Experiments with serumsickness induced by immunisation with bovine serum albumin inrabbits show that small immune complexes are deposited on theepithelial side of the glomerular basement membrane, whereas thelarger immune complexes are deposited mainly in the mesangium.9If HBV antigens with lower molecular weight induce membranousnephropathy while mesangial deposits of HBV antigens with highermolecular weight result in mesangial proliferativeglomerulonephritis with IgA deposits, a mixed picture ofmembranous and IgA nephropathy should be seen in HBV-associated glomerulonephritis, since immune complexes withdifferent molecular weights may be present in these patients. IgAnephropathy and membranouse nephropathy associated with HBVantigenaemia has been reported from Canadal0 and Hong Kong."The ultrastructural finding of spherical viral particles and finelygranular viral particles in the masangium and glomerular basementmembrane respectively is consistent with this concept.’oInterestingly, the Canadian patient’o was a Chinese immigrant.These findings support your editorial view that the properties of

the antigen may be a more important determinant of the type ofglomerulonephritis than the immune response. Confirmation ofthis concept is of more than theoretical importance in the

understanding of immune-complex glomerulonephritis.

Departments of Medicineand Morbid Anatomy,

Prince of Wales Hospital,Shatin, Hong Kong

K. N. LAIF. M. LAI

J. VALLANCE-OWEN

1. Levy M, Kleinknecht C Membranous glomerulonephritis and hepatitis B virusinfection. Nephron 1980; 26: 259-65.

2. Furuse A, Hattori S, Terashima T, et al. Circulating immune complex in

glomerulonephritis associated with hepatitis B virus infection. Nephron 1982, 31:212-18.

3. Takehoshi Y, Tanaka M, Miyakawa Y, et al. Free ’small’ and IgG-associated ’large’hepatitis Be antigen in the serum and glomerular capillary walls of two patients withmembranous glomerulonephritis N Engl J Med 1979; 300: 814-19

4. Hirose H, Udo K, Matsuda I, et al. Deposition of hepatitis Be antigen in membranousglomerulonephritis: Identification by F(Ab)2 fragments of monoclonal antibody.Kidney Int 1984; 26: 338-41.

5. Sluzarczyk J, Michalak T, Nozarewicz-de Mezer T, et al. Membranous

glomerulopathy associated with hepatitis B core antigen immune complexes inchildren. Am J Pathol 1980; 98: 29-39

6. Lai KN, Lai FM, Chan KW, et al. The clinico-pathologic features of hepatitis B virusassociated glomerulonephritis. Quart J Med 1987; 63: 323-33

7. Lai KN, Lai FM, Lo S, Leung A. Is there a pathogenetic role of hepatitis B virus inlupus nephritis? Arch Pathol Lab Med 1987; 111: 185-88.

8. Nagy J, Bajtai G, Sule T, Ambrus M, Deak G, Hamon A. The role of hepatitis Bsurface antigen in the pathogenesis of glumerulopathies. Clin Nephrol 1979; 12:109-16.

9. Germuth FG, Rodriguez E. The immunopathology of the renal glomerulus. Boston:Little, Brown, 1973.

10. Magil A, Webber D, Chan V. Glomerulonephritis associated with hepatitis B surfaceantigenemia Report of a case with features of both membranous and IgAnephropathy. Nephron 1986, 42: 335-39.

11. Lai KN, Lai FM, Lo S, Lam C. IgA nephropathy and membranous nephropathyassociated with hepatitis B surface antigenemia. Hum Pathol 1987; 18: 411-14.

INNERVATION OF ZYGAPOPHYSEAL JOINTSYNOVIAL FOLDS IN LOW-BACK PAIN

SiR,—Discussions of low-back pain (with or without leg pain)have tended to emphasise the intervertebral disc as a major cause ofsymptoms, since no nerves are thought to be present in lumbarzygapophyseal joint synovial folds. However, transmission electronmicroscopy and silver and gold chloride impregnation techniqueshave lately demonstrated that the synovial folds (particularly thelarge lumbosacral zygapophyseal joint synovial folds 1) have 0-2-0.4tm paravascular nerves2-4 and 06-12 lun myelinated nerves whichare remote from blood vessels.3,4 Substance P immunofluorescentnerves were demonstrated in human lumbosacral zygapophysealjoint synovial folds.5 Substance P, a physiologically potentneuropeptide, is thought to participate in nociceptive transmissionof nerve impulses.6 Therefore, in the absence of positiveradiographic findings, innervation of the synovial folds may haveclinical significance in low-back pain, should the synovial foldsbecome pinched between the facet surfaces, with resultingtraumatic synovitis. The innervation may explain whyfluoroscopically controlled injections of steroids and anaesthetic

into zygapophyseal joints can give relief from low back pain with orwithout sciatica.7,g The innervation may also explain why gentlemobilisation of the zygapophyseal joints provides relief in somecases of low-back pain-presumably as a result of freeing synovialfolds which have become trapped between the facets.

Department of Anatomy and Human Biology,University of Western Australia,Nedlands, Western Australia 6009 L. G. F. GILES

1. Giles LGF, Taylor JR. Intra-articular synovial protrusions in the lower lumbar

apophyseal joints. Bull Hosp Joint Dis 1982; 42: 248-55.2. Giles LGF, Taylor JR, Cockson A. Human zygapophyseal joint synovial folds. Acta

Anat 1986; 126: 110-143. Giles LGF, Taylor JR. Innervation of lumbar zygapophyseal joint synovial folds. Acta

Orthop Scand 1987; 58: 43-46.4. Giles LGF, Taylor JR. Human zygapophyseal joint capsule and synovial fold

innervation. Br J Rheumatol 1987; 26: 93-98.5. Giles LGF, Harvey AR. Immunohistochemical demonstration of nociceptors in the

capsule and synovial folds of human zygapophyseal joints. Br J Rheumatol (mpress).

6. Jessell TM. Pain. Lancet 1982; ii 1084-88.7. Kirkaldy-Willis WH. A comprehensive outline of treatment. In: Kirkaldy-Willis WH,

ed. Managing low back pain. Edinburgh: Churchill Livingstone, 1963: 147-60.8. Aprill C. Lumbar facet joint arthrography and injection in the evaluation of painful

disorders of the low back. International Society for the Study of the Lumbar Spine(Dallas, 1986) abstr.

MULTIPLE PREGNANCY AND ASSISTEDREPRODUCTION

SIR,--Our main concern about the Voluntary LicensingAuthority’s (VLA’s) 1987 guidelines is that a non-statutoryauthority is seeking to impose strict limitations on the clinicaltreatment which infertility patients receive. Separate, but of equalimportance, to this fundamental issue is the concern that the VLA’sdirectives have been made without taking into account, or

publishing, analysis of all the UK data available to them. It is, forexample, unsatisfactory to state there is evidence to show that only3, or exceptionally 4, oocytes ensure an optimal outcome withgamete intrafallopian transfer (GIFT) without producing theevidence. A statistical analysis of over 1000 GIFT proceduresperformed in our Unit is readily available to the VLA.The VLA’s recommendation on the number of embryos to

transfer after in-vitro fertilisation (IVF) is based upon concernsabout multiple pregnancies of high order, but no evidence is

presented on what proportion of multiple births in the UK resultfrom IVF. It has always been our opinion that natural conception,associated with medical induction of ovulation, is a majorcontributor to multiple births of high order, as it was for the

septuplets delivered in Liverpool last month.We have done a survey on multiple births (triplets or more) in

1984-86 by asking special care baby units (SCBUs) whetherconceptions had been natural, natural after medical induction ofovulation, or IVF. Questionnaires were sent to 192 SCBUs ofwhich 62 (322%) have replied to date. In 27 (44%) there had beenno admissions of triplets or higher multiple births. The results(table) confirm that IVF is a very small contributor to multiplepregnancy births of high order resulting in SCBU admissions in theUK. 13% of admissions of quadruplet births or greater followedIVF treatment, and if triplet births are added the proportion falls to7%. In terms of total cots only 7% were occupied by babiesconceived following IVF.The outcome of fertility treatment is likely to be different in

women with different types of fertility problem. The risk of amultiple pregnancy of high order is likely to be far greater afternatural conception in hypogonadotropic women and some others

NUMBERS OF SETS OF TRIPLETS, QUADRUPLETS, QUINTUPLETS,AND SEXTUPLETS ADMITTED TO 35 SPECIAL CARE BABY

UNITS IN 1984-86