|Year : 2017 | Volume
| Issue : 3 | Page : 247-249
Sixth nerve palsy - Window to a dreaded brain tumor in children (pontine glioma)
Department of Ophthalmology, Andaman and Nicobar Islands Institution of Medical Sciences, Port Blair, Andaman and Nicobar Islands, India
|Date of Web Publication||30-Jan-2018|
Dr. Sujit Das
Department of Ophthalmology, Andaman and Nicobar Islands Institution of Medical Sciences, Port Blair - 744 104, Andaman and Nicobar Islands
Source of Support: None, Conflict of Interest: None
Pontine glioma is a rare tumor and exclusively occurs in children. It originates from the glial (connective/supporting) cells of the brain. In children, they are the leading cause of deaths from brain tumors. The usual age of presentation is later half of first decade. Most of the children die within 18 months of diagnosis. It mostly affects 6th and 7th cranial nerves along with hearing defect.
Keywords: Sixth nerve palsy in children, brain steam tumor, pontine glioma
|How to cite this article:|
Das S. Sixth nerve palsy - Window to a dreaded brain tumor in children (pontine glioma). Kerala J Ophthalmol 2017;29:247-9
| Introduction|| |
A pontine glioma occurs in the “pons” which controls breathing, heart rate, and the nerves and muscles used in seeing, hearing, walking, talking, and eating. Pontine glioma is a rare tumor and exclusively occurs in children. It originates from the glial (connective/supporting) cells of the brain. Gliomas of the brainstem, such as diffuse intrinsic pontine glioma (DIPG) are uncommon in adults, but in children they are the leading cause of deaths from brain tumors. Pontine gliomas grow quickly, so symptoms can appear suddenly and progress rapidly. It is hard to treat and has a poor prognosis.
The usual age of presentation is later half of first decade. Mostly, it affects 6th and 7th cranial nerve and usually bilateral. Involvement of frontopontine cerebellar fiber causes ataxia. Most of the children die within 18 months of diagnosis. Glioma can affect the optic nerve also, where the presenting feature is visual disturbances, proptosis, squint, and exophthalmos.
There is no standard staging system for childhood brain stem glioma. Treatment is based on the following: whether the tumor is newly diagnosed or recurrent and the type of tumor (either a DIPG or a focal glioma). Surgical excision is difficult and not so promising, whereas chemotherapy does not have any role. Hence, external beam radiotherapy is the main way of treatment.
| Case Report|| |
An 8-year-old boy presented with complaining of acute onset of inward deviation of the left eye, horizontal diplopia, and mild headache for the past 2 weeks [Figure 1]. There was unsteadiness and difficulty in using limbs for 3–4 days. No associated history of hearing loss, vomiting, fever, facial asymmetry, muscle paralysis, difficulty in speech and swallowing, and no history of any seizure episode. No history of any trauma. No history of significant illness. No relevant family history was there. On examination, best-corrected visual acuity was 6/6 in both eyes; intraocular pressure was 12 mmHg in both eyes. There was esotropia in the left eye with restricted movement of lateral rectus. Corneal sensation was normal, pupil response was normal, optic disc showed no papillodema. The right eye was absolutely normal. Pediatric and neurologist opinion were taken. Glasgow Coma Scale score was 15/15, no facial/lower motor neuron palsy, plantar reflex showed bilateral extensor, cerebellar signs right > left, gait-ataxic. Noncontrast computed tomography brain-normal [Figure 2], contrast magnetic resonance imaging (MRI) brain showed enhancing pontine glioma of low grade [Figure 3] and no evidence of hydrocephalus. He was then referred to higher center for further management where he underwent external beam radiation and put on steroid. His diplopia and neurological symtoms got better but subsequent MRI brain showed no reduction in size of the tumor. On follow-up, he developed puffiness of face, mild headache, on off vomiting, and no improvement of esodeviation [Figure 4]. No diplopia was present. Best-corrected visual acuity was 6/6 in the right eye, 6/18 in the left eye, no improvement with pinhole. Intraocular pressure was 14 mmHg in both eyes, near vision in right eye N6 and left eye it was N12. Pupillary reaction was normal in both eyes. Lid closure was complete but while during sleep there was mild sclera show in the left eye. Right eye optic disc was normal whereas left eye optic disc showed temporal pallor - rest fundus was normal. Mild ataxic gait was persisting. Surgical intervention was not advised for this patient.
|Figure 3: Magnetic resonance imaging brain (plane and contrast) showing space occupying lesion low grade pontine lesion|
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| Discussion|| |
Pontine glioma mostly affects 6th and 7th cranial nerves along with hearing defect. Hence, any 6th or 7th nerve palsy in children should be evaluated carefully with MRI brain. Early evaluation and early diagnosis along with type of glioma have its prognostic importance. Although pontine glioma occurs as bilateral phenomena, this 8-year-old child presents with insidious onset of unilateral 6th nerve palsy with gait disorder - points toward a cause involving brain steam lesion. Because cancer in children is rare, treatment will be overseen by a pediatric oncologist, neurosurgeon, radiation oncologist, neurologist, rehabilitation specialist, endocrinologist, and psychologist. Dexamethasone is a steroid drug frequently administered to brain stem tumor patients for the swelling and “tightness” of their tumor at the base of their skull. Dexamethasone is an extremely effective medicine for symptomatic swelling associated with the treatment of a brain stem glioma, particularly with radiotherapy. However, dexamethasone is not necessary unless a child has symptomatic swelling.
| Conclusion|| |
Childhood pontine glioma is a rare and dreaded brain cancer with poor survival rate - most of the children die within 18 months after diagnosis. Surgery is not an option for pontine glioma because of its location and external beam radiotherapy remains the standard of treatment.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]