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Re: Different faces of facial paralysis

Dear editor,

I read the article of Dr M Riordan on investigation and treatment of facial paralysis in the April issue of the journal with a special interest. It is indeed a well-composed article. However I would like to elaborate some interesting points.

1.Although facial nerve paralysis is the commonest cause of facial weakness, weakness of facial muscles forms another interesting spectrum of facial weakness. Myotonic dystrophy and infantile facioscapulohumeral syndrome can present as facial weakness. Congenital myasthenia gravis and juvenile immune mediated myasthenia may be relevant to remember as differential diagnosis.[1]

2.Certain infections like tuberculosis and leprosy, although uncommon in UK, should not be ignored as we may continue to see them in immigrant population. Tubercular meningitis may start with fever and facial nerve palsy.[2] Infectious mononucleosis is another not too rare offender.

3.The author has rightly pointed out the importance of careful examination of the ear including hearing acessment. An unusual but very interesting cause of facial weakness is presence of an intraaural tick. Salivary glands of the tick secrete a toxin that either impairs the synthesis or the secretion of acetylcholine in the motor end plate of facial muscles [3]. Happily enough, the nerve weakness disappears with the removal of the tick.

4.Perinatal traumatic facial weakness is usually a disorder of a large term infant, delivered vaginally after a prolonged labour. Medico-legally it is important to remember that it is more often caused by facial nerve compression against the maternal sacrum during labour even before the obstetricians lay their hands on the baby.[1] Although the majority recover spontaneously, close attention to eye care is vital. It is also important not to misdiagnose absent depressor anguli oris as facial weakness.

5.Incidence wise brain stem glioma is as important as leukemia as a cause of facial weakness. It is interesting to point out that unlike adults, 17% of children with neurofibromatosis type 2 can present as facial weakness.[4]

6.Although uncommon, toxins will be an important differential diagnosis to the list of causes of facial weakness. Ingestion of ethylene glycol, an antifreeze agent, may present with facial diplegia. Inhalation of chlorocresol, a compound used in industrial production of heparin, is a recognised cause of recurrent facial weakness[1]

7.Vasculitic disorders (Polyarteritis nodosa, SLE),Sickle cell anaemia and childhood migraine can also present with facial weakness[5]

Dr Samudra Mukherjee
Senior House Officer
Department of Paediatrics
The Leeds General Infirmary
Clarendon Wing, Belmont Grove
Leeds LS2 9NS, UK

References:

(1) Fenichel GM. Clinical pediatric neurology-a signs and symptoms approach,3rd ed. W.B Saunders, 1997.

(2) Yaramis A, et al. Central nervous system tuberculosis in children: a review of 214 cases.
Pediatrics 1998;102:E 49.

(3) Indudharam R, Dharap AS, HoTM. Intraaural tick causing facial palsy.
Lancet 1996;348:6-13.

4.Evans DG, Birch SM , Ramsden RT. Paediatric presentation of Type 2 neurofibromatosis.
Arch Dis Child 1999;81(6):496-9.