Download Isolated Benign Unilateral Abducent Nerve Palsies in Young

Brief Report
Isolated Benign Unilateral Abducent
Nerve Palsies in Young Children
- A Case Series
Sanitha Sathyan DNB, Meena C.K DNB, Elizabeth Joseph K MS
ABSTRACT
Aim: To report a case series of benign isolated abducent
nerve palsies, in 6 children, diagnosed in 2 months at a
tertiary care centre from within an area of 30 square km.
Methods: This retrospective case series includes 6
patients < 18 months of age with acute onset abducent
nerve palsy, who presented during a period of 2 months.
There was no history of prior trauma/ neurological disease.
The mean deviation was 40 prism diopters and there was
-3 to -4 limitation of abduction in the involved eyes. All
underwent MRI brain, which was normal.
Results: All the patients had partial recovery within 2-5
days and total recovery in 10-14 days after treatment with
oral steroids.
Conclusion: This case series supports the entity of
benign idiopathic sixth nerve palsy and emphasizes
on the importance of supportive treatment in otherwise
asymptomatic young children. Key words: Abducent palsy,
children, isolated
Introduction
Acute onset sixth nerve palsy in a child raises suspicion
of serious neurological disease like raised intracranial
pressure, pontine glioma and meningitis. However, benign
self resolving sixth nerve palsies are also reported. In 1967,
Knox, Clark, and Schuster1 reported a series of 10 children
with spontaneous sixth cranial nerve paralysis that occurred
about 7 to 21 days after a nonspecific illness. Symonds2
, Bixenman and Von Noorden et al3 also have reported
isolated self resolving abducent nerve palsies. Acquired
sixth nerve palsies following immunisation have also been
reported.4,5 Clustering of the cases of acute abducent nerve
palsies have not been reported in literature so far.
Materials and Methods
We report a retrospective case series of 6 patients < 18
months of age, who presented within a period of 2 months,
with acute onset of sixth nerve palsy, which resolved with
supportive therapy.
All the patients presented to us with acute onset deviation
of eyes and associated face turn to the same side, within 2
days of onset of symptoms. Mean age was 13.83 months (10
– 18 months). There was no history of trauma, documented
fever, previous ocular deviations or neurological disease.
The mean deviation by the Modified Krimsky test was 40
prism diopters (30-60 prism diopters) and there was -3 to
-4 limitation of abduction in the involved eyes. Cycloplegic
refraction, anterior segment and fundus examinations were
otherwise normal.
All the patients had normal neurological evaluation including
MRI brain and were started on oral prednisolone (1 mg/
kg body weight), which was tapered over 4 weeks, with
a presumed etiology of transient neuritis of the abducent
nerve.
Results
All the patients had partial recovery within 2-5 days and
total recovery with a mean of 13.66 days (10-14 days). (ref:
Table:1)
Table:1 Clinical profile of patients:
Age
Case
(months)
Partial
Esotropia
recov(prism
ery
diopters)
(days)
Total
Recovery
(days)
10
1
10
60
2
(recurrence
2 months later)
2
11
40
5
14
3
12
30
3
10
4
18
40
3
14
5
14
40
2
10
6
18
30
3
14
Kerala Journal of Ophthalmology | 83 |
Address for Correspondance: Little Flower Hospital, Angamaly - 683 572. Email: [email protected]
Vol. XXVI, No.1, March 2014
One child had a second episode of acute onset sixth nerve
palsy in the same eye 2 months after the steroids were
weaned off. MRI brain was normal in this episode also and
the patient was restarted on oral steroids. Partially recovery
was seen in 3 days and total recovery in 7 days.
Discussion
Benign self resolving unilateral sixth nerve palsy in young
children is a relatively rare diagnosis.
The etiology of benign, self resolving, unilateral sixth nerve
palsies remain uncertain and none of the published literature
points to a definitive cause. The major predisposing
conditions listed in the series by Knox et al1 included viral
infection, otitis media and thrombosis of the inferior petrosal
sinus. Symonds et al2 postulated that since the sixth nerve
and the inferior petrosal sinus pass through a tightly fitting
dural sheath of Dorello’s canal, the compression of the
nerve could readily occur if the sinus becomes thrombosed.
Functional recovery of the sixth nerve may occur with
organization and canalization of the clot .
A case of recurrent sixth nerve palsy in a child of 5 episodes
was reported by Bixenman and Von Noorden et al3, indicating
a viral neuritis. They postulated that benign sixth nerve palsy
of childhood may have the same immunological basis similar
to post-infectious processes like Guillian-Barre syndrome.
With recovery from the initial episode, the abducens nerve
may have become predisposed to recurrent inflammatory
episodes, triggered by febrile illnesses. Acquired sixth nerve
palsies after immunisation have also been reported.4,5
All these cases reported in our series in children less than 18
| 84 | Kerala Journal of Ophthalmology
months of age were seen in a period of 2 months and 4 of the
cases were reported from an area of 30 square kilometres,
which points toward a probable infective etiology. Though
there was no definite history of viral infection or trauma, the
relatively benign course with recovery within 2 weeks suggest
a transient neuritis of the sixth nerve, probably triggered by
an insignificant viral infection. Also the one recurrent case of
sixth nerve palsy suggests a possible immunological basis
as proposed by Bixenman and Von Noorden et al.5
Though we could not suggest a definitive etiological
diagnosis, all the patients in our series were empirically
treated with systemic steroids with full recovery within 2
weeks. This report is in favour of the entity called benign
idiopathic sixth nerve palsy and emphasizes on the
importance of avoiding invasive procedures like lumbar
puncture in otherwise asymptomatic infants.
References
1. Knox DL, Clark DB, Shuster FF. Benign VI nerve palsies
in children. Pediatrics. 1967;40:560–564
2. Symonds, C. P. Annals of Royal College of Surgeons
England 1952: 10- 347
3. Bixenman WW, von Noorden G. Benign recurrent VI
nerve palsy in childhood. J Pediatr Ophthalmol
Strabismus. 1981 18(3):29–34.
4. Werner DB, Savino PJ, Schatz NJ. Benign recurrent sixth
nerve palsies in childhood secondary to immunization or
viral illness. Arch Ophthalmol 1983; 101:607-8
5. A McCormick, S Dinakaran. Recurrent sixth nerve palsy
following Measles Mumps Rubella vaccination. Eye
2001: 15: 356–357