The ultrastructural study of a skeletal muscle biopsy in a case of familial oculopharyngeal muscular dystrophy confirms the presence of 7-8 nm wide tubular filaments within muscle fiber nuclei.

MUSCLE & NERVE 5~735-737 1982

NUCLEAR INCLUSIONS IN OCULOPHARYNGEALMUSCULAR DYSTROPHY

JEAN-JACQUES R. MARTIN, MD, CHANTAL M. CEUTERICK, MS, and RUDOLF J. MERCELIS, MD

Oculopharyngeal muscular dystrophy (OPMD) presents with characteristic clinical and genetic fea- tures including autosomal dominant inheritance, onset in later life, progressive palpebral ptosis, im- paired swallowing and spreading of motor weak- ness to facial and limb-girdle m ~ s c l e s . ' ~ Light mi- croscopy of muscle biopsies has shown rimmed vacuoles in small fibers and other nonspecific alter- ations." ~ n I y one electron microscopic report'" mentions the presence of intranuclear tubular filaments in less than 7% of the muscle fiber nuclei. The purpose of our report is to confirm this finding.

CASE REPORT

A 53-year-old female patient of Dutch origin pre- sented with a bilateral palpebral ptosis of 10 years duration, nasal speech, and swallowing difficulties

From the Department of Neuropathology Born-Bunge Foundation and University of Antwerp Antwerp Belgium

Acknowledgments The financial support of the Belgian Foundation for Scientific Medical Research (grant 3 0004 81) the Baron Charles Bracht Foundation and Mrs C Vincentelli is gratefully acknowledged Dr L Mol referred the patient to us

Address reprint requests to Dr Martin at the University of Antwerp Building T Room 5-18 UIA Universiteitsplein 1 8-2610 Wilrijk (Ant- werpen) Belgium

Received for publication May 12 1982 revised manuscript accepted for publication July 30 1982

01 48-639WO50910735 $01 2510 1982 John Wiley & Sons Inc

for 3 years. Clinical examination confirmed these signs and revealed also a slight weakness of the shoulder and pelvic girdle muscles (grade 4 of the Medical Research Council Memorandum Scale). Eyegrounds were normal. Electrocardiography gave normal results. Normal motor and sensory conduction velocities were recorded. A myasthenia test was negative. Electromyography showed a slight myogenic involvement of the upper facial muscles. A biopsy was performed in the left del- toid muscle.

Family history was positive, the patient's father and a paternal uncle having had similar clinical features 15 to 20 years before death, which occurred at the respective ages of 73 and 70 years. No muscle biopsy was available from those 2 patients.

METHODS

Classical light- and electron microscopic methods were used."

RESULTS

Light microscopy showed a few atrophic fibers, rare necrotic fibers, and sniall amounts of rimmed vacuoles. Examination of cryostat sections stained with hernatoxylin-eosin was not contributory as far as the subsarcolemmal nuclei were concerned. Sel- dom did one find with oil-immersion a few7 nuclei with an eosinophilic central area instead of the usual hematoxylaffinic staining of chromatin. His-

Oculopharyngeal Muscular Dystrophy MUSCLE & NERVE NoviDec 1982 735

+-+--- A-

I0 20 30 90

TYPE I

_1 r TYPE 2

toenzymology revealed a normal checkerboard pattern with type 1 (49%), type 2a (36%), and type 2b (1 5%) fibers. The atrophic fibers contained the rimmed vacuoles and belonged nearly exclusively to type 1. Quantitative studies on 5 12 muscle fibers indicated a normal distribution of the lesser diame- ters (Fig. l ) , negligible atrophy and hypertrophy factors, and normal variability coefficients for all types. Enzyme histoenzymatic techniques revealed no other significant features. No immunohistolog- ical techniques against actin or desmin filaments were applied.

'l'he examination of 174 muscle fiber nuclei on serni-thin sections showed a central area of translu- cency in 8 of them (4.6%).

Electron microscopy confirmed that the rimmed \.acuoles corresponded to areas of focal destruc- tion bvith pseudomyelinic profiles reaching a diam- eter of 4 to 6 pm. A few riiiiscle fibers were totally

50 60 70 80 demwyed and invaded by rriacrophaxes containing - ._ f igure 1 : Morphometric data. Normal distribution of the lesser lamellitr debris. Inclusions were found in the cen: diameters of type 1 and type 2 muscle fibers. Abscissa Dame- ters in micrometer:;. Ordinate' Percentage expressed in function of the total number of fibers.

t,.i,l of a few nuclei ( ~ i ~ . 2 ) , chromatirl being pushed aside. Their intranuclear location could be easily ascertained by the absence of a nuclear mem- lxtne between them and the chromatin on serial sections. The inclusions were composed of 7- to 8- nm wide filaments giving sometimes the inipres- sion of' heing hollow on perfectly transverse sec-

Figure 2: lntranuclear filaments. Their intranuclear location is demonstrated by the absence of nuclear membrane between them and the chro- matin at the upper part of the photograph. When cut transversely, the filaments appear hollow; on longitudinal sections they show sometimes a transverse periodic striation. Inset: lntranuclear filaments at low magnification. (Standard electron microscopic techniques.)

736 Oculopharyrgeal Muscular Dystrophy MUSCLE & NERVE NoviDec 1982

tions while, on longitudinal sections, transverse periodic striations could sometimes be observed. The filanients could be parallel to each other, forming interwoven bundles or palisades; they could also run in various directions. Such filaments were found in nuclei from otherwise normal- looking fibers. They were not present in the sarco- plasm. Satellite muscle cells, capillaries, and fibroblasts were normal.

DISCUSSION

The most characteristic feature in skeletal muscles of OPMD patients resides in the presence of rimmed vacuoles,".' which are not, however, spe- cific for this condition. * Abnormal mitochondria

aracrystalline mate ria^'.^ or fingerprint bodies have also been described but are even less specific. The 8-nm thick filaments discovered in three cases by Tome and Fardeau'" and in our case have not been reported in other examples of OPMD as yet.'

Several questions can be raised as to the distri- bution, the specificity, and the nature of such intranuclear filaments. Up to now they have only been described in biopsied deltoid muscles but they should be looked for, in autopsy rnaterial, in

Y

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more severely affected muscles such as the levator palpebrae or the pharyngeal muscles.','" The filaments found in OPMD are certainly different by their size and location from the much larger (1 5 to 18 nm) intra- and extranuclear filaments found in inclusion body myositis,'2536 or from those found in polymyositis.9 One apparent exception is the case reported by Schochet and McCormick" of a polyniyositis with intranuclear bundles of 7 nni- wide filaments; however, their strictly parallel orientation, smooth appearance, and punctate aspect, respectively, on longitudinal and on trans- verse sections represent differentiating features. Carpenter and associates' believed them to repre- sent actin filaments.

The filaments observed in OPMD differ also from nonviral intranuclear inclusions described in a variety of cells and of neurologic diseases; l 2 these nonviral inclusions are mostly wider, probably arise from chromatin, and are often found in au- topsy material or when the fixation is suhoptimal. The size of the OPMD filaments makes them also less likely to derive from chromatin as a result of aging.

Their exact nature and their relevance to OPMD cannot presently be assessed.

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I S . TomP FXIS, Fardeau 31: Nuclear inclusions in oculo- pharyngeal dystrophy. Atlu I t ' P t t u q k z t f i o l (Berl) 49:8.5-87, 10x0.

1.1. \'ictor hi, Hayea K, Adanis RD: Oculopharyngeal muscular dystrophy. A faniilial disease of late like characterized by dysphagia and progressive ptosis of the eyelids. "V E7jgl.J M r d 267:1267-1272, 1962.

Oculopharyngeai Muscular Dystrophy MUSCLE & NERVE NoviDec 1982 737