LETTERS

Is Conjunctival Biopsy Useful for Diagnosis of Neuroaxonal Dystrophy? Claudio Crisci, MD,* Manuel R. Gomez, MD,? George G. Hohberger, MD,$ Caterina Giannini, MD,' and Peter James Dyck, MD'

Increasingly, our colleagues have asked us to biopsy conjunc- tiva from infants suspected of having neuroaxonal dystrophy (ND). Typical alterations resulting from N D 11, 27 or other inborn errors of metabolism 13, 47 have been reported in biopsied conjunctiva.

Because the density, size distribution, and ultrastructural variability of nerve fibers in normal conjunctiva have not been reported, it is difficult to provide an adequate assess- ment of abnormality in this tissue. Study of normal tissue might also be useful for determining the optimal amount of tissue needed for an adequate evaluation.

To this end, we obtained small snippets (at least 2 x 3 mm in area) of conjunctiva from 7 infants and young children who had operations for strabismus. Informed consent (ap- proved by the Mayo Institutional Review Board) had been obtained from the parents.

In the operating room, the tissue was immersed directly into 2.5% glutaraldehyde in cacodylate buffer (pH 7.38, 10°C). The tissue was diced into s m a l l blocks, fixed over- nght, and after osmication, embedded into epoxy. Nerve fibers then were evaluated in multiple semithin sections and in electron micrographs. Myelinated fibers were encountered in half of the tissue blocks. We evaluated all blocks from each subject; only 3 subjects had more than 10 myelinated fibers for evaluation (Table). Often the fibers were obliquely oriented, making interpretation of the morphological abnor- malities difficult.

Our study of biopsied specimens of normal conjunctiva in children has shown that the test is time consuming and there- fore expensive and may provide insufficient fibers for analy- sis because of their uneven distribution. To obtain an ade- quate sample of myelinated fibers might require an even larger biopsy specimen, which is not desirable. These facts have led us to conclude that conjunctival biopsy, although

Fwquency of Myelinated F i h s in the Conjunctiva in 7 Children

useful for the detection of some metabolic storage disorders not solely confined to nerve fibers 157 may not be as sensitive as desired for the early detection of N D because too few fibers may be encountered.

'Peripheral Neuropathy Research Luboratoty ?Section of Pediatrdc Neurology $Department of OphthalmoIogy Mayo C h i c and Mayo Foundation Rochester, MN

Dr Crisci was supported by the Fondazione Clinica Del Lavom, Italy.

References 1, Arsenio-Nunes ML, Goutieres F. Diagnosis of infantile neuroax-

onal dystrophy by conjunctival biopsy. J Neurol Neurosurg Psy-

2. Marrin JJ, Leroy JG, Libert J, er al. Skin and conjunctival biopsies in infantile neuroaxonal dystrophy. Acta Neuropathol 1979;45:

3. Arsenio-Nunes ML, Gouderes F, Aicardi J. An ultramicroscopic study of skin and conjunctival biopsies in chronic neurological disorders of childhood. Ann Neurol 1981;9:163-173

4. Ceuterick C, Martin JJ. Diagnostic role of skin or conjunctival biopsies in neurological disorders. An update. J Neurol Sci 1984;65:179-191

5. Mazow ML. The efficacy of conjunctival biopsy as a screening technique in lysomal storage disorders. Trans Am Ophthalmol

chiatry 1978;41:511-515

247-251

Soc 1987;95:471-497

Prevalence of Lev Bodies in Alzheimer's Disease W. R. G. Gibb, MD, MRCP, and A. J. Lees, MD, FRCP

Joachim and coworkers {l] found that 23 of 131 (18%) brains of patients fulfilling a pathological diagnosis of Alz- heimer's disease (AD) showed nigral Lewy bodies; 14 (1 1%) and 9 (7%) of these patients were judged to have Parkinson's disease (PD) and incidental Lewy body disease, respectively.

No. of No. of Blocks Blocks with No. of Subject Age (yr) Tissue Blocks with MFs >5 MFs MFs/Subject

1 1.1 2 1.1 3 1.8 4 2.0 5 2.0 6 8.0 7 9.0

Total Median

3 9 5 7 4 6 4

38 5

2 3 3 5 1 3 2

19 3

2 6 4

59 3

52 39

165 6

MFs = myelinated fibers.

Copyright 0 1989 by the American Neurological Association 691