LETTER TO THE EDITOR

Ocular motor deficits in oculopharyn-

geal muscular dystrophy

D. Gautiera, I. Penisson-Besnierb,

S. Rivaud-Pechouxc, C. Rabautea

and D. Mileaa,d

aDepartment of Ophtalmologie, Centre

Hospitalier Universitaire d�Angers;bDepartment of Neurologie, Centre de

reference des maladies neuromusculaires,

Centre Hospitalier Universitaire d�Angers;cPierre et Marie Curie Universite Paris-6,

INSERM URMS 975, CNRS 7225, Paris,

France; and dDepartment of Ophthalmol-

ogy, Glostrup Hospital, Copenhagen

University, Denmark

Correspondence: D. Gautier, Department

of Ophtalmologie, Centre Hospitalier

Universitaire d�Angers, 4 rue Larrey,

49933 Angers Cedex 9, France (tel.:

+33241353274; fax: +33241354264;

e-mail: dlgautier@yahoo.fr).

Keywords: amplitudes of saccades,

ocular motility, oculopharyngeal muscular

dystrophy, saccades, speed of saccades

Received 6 September 2011

Accepted 12 December 2011

Sir,

Oculopharyngeal muscular dystrophy

(OPMD, MIM #164300) is a rare domi-

nantly inherited myopathy caused by a

short GCG-triplet expansion in the

poly(A) binding protein nuclear 1 gene

(PABPN1) [1]. Presenting signs, starting in

late adulthood, are slowly progressive

ptosis and dysphagia, with subsequent

possible involvement of other voluntary

muscles. Extraocular eye movements in

OPMD are to date poorly described [2].

The aim of this pilot study was to quantify

the ocular saccades in patients with

OPMD.

Subjects and methods

Eye movements of patients with geneti-

cally confirmed OPMD were recorded

using a new dedicated infrared video

oculography device (Mobile EyeBrain

Tracker, e(ye)BRAIN, Ivry-sur-Seine,

France, http://www.eye-brain.com). This

study, approved by the local ethics com-

mittee, was conducted in accordance with

the Declaration of Helsinki.

Characteristics of 20� horizontal sac-

cades (latency, amplitude, gain, and peak

velocity) of left and right eyes were

assessed using a horizontal pro-saccade

(gap) task both in the OPMD group and

in a matched healthy control group (28

volunteers, mean age 71.5 ± 11.8 years).

Because of ptosis, only horizontal

saccades were analyzed. Between-group

comparisons were made using the Mann–

Whitney U test, and P values <0.05 were

considered to be significant.

Results

Six patients with genetically confirmed

OPMD were included, four men and two

women (mean age 75 ± 12.3 years),

originating from five families. All were

heterozygous for the mutation, and the

mean size of GCG expansion was 9

(8–11). Age at referral ranged from 43 to

69 years (mean 57.5 years). The present-

ing symptoms were ptosis, dysphagia, or

limb weakness either in isolation or in

combination. Clinical ocular motor

examination was considered �within nor-

mal limits� by the referring neurologist, in

all included patients. The remainder of the

neuro-ophthalmic examination was nor-

mal. A various degree of proximal limb

weakness was found in five patients.

Horizontal saccades were significantly

slower in patients with OPMD than in

healthy controls (P = 0.00015). Latency,

amplitude, and gain showed no difference

between the two groups (Table 1).

Discussion

Various degrees of ocular motor involve-

ment in OPMD have been previously

described, but only on a clinical, qualita-

tive basis [3]. To the best of our knowl-

edge, no ocular motor study specifically

addressed this question in the past. Our

quantitative pilot study discloses a new

finding: reduced saccades speed, associ-

ated with totally preserved amplitude of

eye movements (explaining the normal

clinical examination). Because of the small

size of this pilot study, we could not

perform correlations between the change

in saccades speed and the progression of

the disease over time. The pathophysio-

logical explanation of the dissociation

between the impaired speed and the

normal amplitude of saccades remains

unclear, and further oculographic studies

should include patients with clinically

impaired eye movements.

References

1. Brais B, Bouchard J-P, Xie Y-G, et al. Short

GCG expansions in the PABP2 gene cause

oculopharyngeal muscular dystrophy. Nat

Genet 1998; 18: 164–167.

2. Hill ME, Creed GA, McMullan TF, et al.

Oculopharyngeal muscular dystrophy:

phenotypic and genotypic studies in

a UK population. Brain 2001; 124: 522–526.

3. Bouchard JP, Brais B, Brunet D, Gould PV,

Rouleau GA. Recent studies on oculopha-

ryngeal muscular dystrophy in Quebec.

Neuromuscul Disord 1997; 7(Suppl. 1):

S22–S29.

Table 1 Saccade characteristics in the two groups

Latency (ms) Amplitude (�) Gain Vmax (�/s)

Patients (n = 6) 284 ± 59 19.5 ± 1.6 0.95 ± 0.04 291 ± 49

Controls (n = 28) 253 ± 56 19.9 ± 1.6 0.97 ± 0.06 505 ± 57

P value >0.05 >0.05 >0.05 0.00015

Latency, amplitude value, (Vmax) peak velocity, (Gain) accuracy. There was a significant

reduction of Vmax in patients with oculopharyngeal muscular dystrophy.

e38� 2012 The Author(s)

European Journal of Neurology � 2012 EFNS

European Journal of Neurology 2012, 19: e38 doi:10.1111/j.1468-1331.2011.03657.x