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Seventh Cranial Nerve Palsy: The First Sign of Multiple Sclerosis in A Young Children

Multiple sclerosis (MS) is a chronic autoimmune inflammatory
disease of the central nervous system characterized pathologically
by demyelination and subsequent axonal degeneration...


Introduction
Multiple sclerosis (MS) is a chronic autoimmune inflammatory disease of the central nervous system characterized pathologically by demyelination and subsequent axonal degeneration [1,2]. In childhood,MS is a rare disease;overall incidence is less than 1 per 100000 children and overall prevalence is from 0.7 to 26.92 per 100 000 children [3]. It mainly involves adolescents, but rarely it can also affect children younger than 10 years old.The clinical onset in children is variable: isolated optic neuritis and isolated brainstem dysfunction are more frequent, but encephalitic signs, such as disorders of consciousness, headache, vomiting, seizures are also observed [4]. Acute disseminated encephalomyelitis (ADEM) is the initial diagnosis in 16% of children suffering from MS [5]. The 2017 International McDonald multiple sclerosis diagnostic panel proposed modifications to improve diagnostic accuracy, simplify application of the diagnostic criteria, and enhance timeliness of the diagnosis of multiple sclerosis, reducing the misdiagnosis.
These diagnostic criteria perform well in identifying children with multiple sclerosis and they are also applied in children younger than 11 years at presentation without clinical features of ADEM [6].
Over the last three decades, few cases on the association between peripheral demyelinating diseases and MS have been reported in literature [7]. One of the rarest correlations is that between MS and seventh nerve palsy [8][9][10].Peripheral facial palsy is a common disease in children. Viral infections, trauma, hereditary causes, and malignancies are some of the etiological reasons. In approximately half of cases, the etiology is not identified, suggesting a diagnosis of"Bell's palsy" [11,12].We describe the case of a 9-year-old child who was admitted for a recent headache, unilateral facial palsy, nystagmus and vomiting, and only after performing a brain MRI and other investigations the diagnosis of MS was made.

Case Report
A 9-year-old male patient was admitted to the Emergency Room for signs of seventh cranial nerve palsy in the last 24 hours, which occurred after seven days of frontal headache. He had never presented neurological symptoms before. After a Neuropsychiatric evaluation, an emergency cranial CT scan was performed, tested negative for bleeding signs and brain masses. Therefore, a brain MRI was programmed. However, for the recurrence of headache associated with vomiting, A. returned to our department. On physical examination, we observed an asymmetric closure of the right eyelid and buccal asymmetry, like peripheral paresis of the right

Discussion
MS is a chronic inflammatory autoimmune disease, characterized by recurrent episodes of demyelination and axonal degeneration of CNS disseminated in time and space [1,2]. MS is a rare pediatric disease and it mainly involves adolescents, but in extremely rare case it can also affect children under 10 [13]. The etiopathogenesis is still not clear and the triggers of the autoimmune reaction is actually unknown. Probably environmental and infectious factors contribute, in genetically predisposed subjects, to the development of MS. Disease onset during pubertal and post-pubertal age is clinically similar to the adult one, and is characterized by ataxia, dizziness, sensory deficits. Clinical presentation in younger children is more common with optic neuritis, isolated brain stem syndrome and encephalopathy symptoms like headache, vomiting, seizure and/or altered consciousness [4,13]. In our patient, the first clinical sign was the seventh cranial nerve palsy whose association with MS has been rarely described. Fukazawa and colleagues reported facial palsy as first symptom of MS in 4.7 % of 107 patients with MS [8]. Ivankovic and Demarin described a 35-year-old woman with MS initially misdiagnosed with Bell's palsy [9].
Moreover, Saleh and colleagues described an MS onset with seventh cranial nerve palsy in a 21-year-old patient [10]. Therefore, In MS patients, facial palsy may appear at the onset of the disease and it may be misdiagnosed as Bell's palsy.In our case, peripheral facial paralysis was associated with other neurological signs and symptoms, so the clinical picture was suspicious for a more complex diagnosis, rather than a simple Bell's palsy. In concordance with the Bell's palsy guideline development group (GDG) diagnostic imaging should not routinely performed, excepting for the presence of other neurological findings [14]. Therefore, the brain MRI was warranted, and it revealed a fundamental exam for the diagnosis.
In our case the diagnosis of MS was made on clinical, laboratory and radiologic findings, according to McDonalds 2017 criteria [6,15] (Table 1)   Useful investigation for differential diagnoses between CNS demyelinating inflammatory disease is testing for anti-AQP4 and anti-MOG antibodies. Anti-AQP4 antibodies are eleveted in neuromyelitis optic spectrum disorders (NMOSD) [16]. Anti-MOG antibodies are more frequent in ADEM and numerous pediatric studies suggest that positivity for these antibodies is predictive of CNS demyelinating disease other than MS [17][18][19].In our case, negativity for both anti AQP4 antibodies and anti MOG antibodies supported the diagnosis of MS.In conclusion, we can assert that making diagnosis of MS might be complex, given the variability of clinical manifestation at the onset especially in young children. As evident in our case, the seventh cranial nerve palsy, particularly when associated with other neurological signs and symptoms, should not be underestimated by the clinicians. So, it is important to keep in mind that in rare cases, peripheral facial palsy can also be a presenting sign of MS.