Pendular See-Saw Nystagmus: A Rare Presenting Manifestation of Craniopharyngioma

ABSTRACT

Pendular see-saw nystagmus is an extremely rare form of nystagmus characterised by cyclical movement of the eyes with a conjugate torsional component and a disjunctive vertical component. Intorsion and elevation of one eye is accompanied by simultaneous extorsion and depression of the contralateral eye. Most commonly it results from a suprasellar/parasellar mass compressing the meso-diencephalic region. Herein, we report a case of a 5-year-old girl who presented with pendular see-saw nystagmus secondary to a craniopharyngioma. The nystagmus resolved following excision of the lesion.

A 5-year-old girl presented due to ‘twitching’ movements of her eyes. They were initially noticed by her parents six months previously and had been persisting since. The child was otherwise asymptomatic. She had had an uneventful perinatal period and had attained her motor, verbal and social milestones on time. Physical examination revealed a short child (height standard deviation score −2.4). She had pendular see-saw nystagmus (see video in online supplemental material). There was no abnormal head tilt or posturing. Her extraocular movements were full in both eyes. The pupils were symmetrical and reacting appropriately to light. Uniocular distance visual acuity was 6/9 in both of her eyes (using the Tumbling E chart), however, on confrontation she had a bitemporal hemianopia. Fundus examination showed mild bilateral temporal optic disc pallor. The rest of the physical examination was grossly normal and she did not have any focal neurological deficits. Perimetry was attempted, however, she was uncooperative.

Computerised tomography of the head was performed, which showed a hypodense suprasellar mass with peripheral rim calcification (Figure 1). Subsequently, magnetic resonance imaging (MRI) revealed a large (3.2 × 2.8 × 3.6 cm), cystic sellar-suprasellar mass. The lesion caused superior displacement of the optic chiasm and reached up to the suprasellar cistern and floor of the third ventricle (Figure 2a,b). The radiological features were consistent with a craniopharyngioma. An anterior pituitary profile revealed secondary hypocortisolism, secondary hypothyroidism and low insulin-like growth factor-1, suggestive of growth hormone deficiency.

Figure 1.

Non-contrast computerised tomography showing a hypodense suprasellar lesion with peripheral rim calcification

Figure 2.

Magnetic resonance image showing a cystic sellar-suprasellar mass appearing hypointense with peripheral rim enhancement on the T1-weighted post-gadolinium coronal image (2a) and hyperintense on the T2-weighted sagittal image (2b). The lesion measures 3.2 × 2.8x3.6 cm and causes superior displacement of the optic chiasm and reaches the suprasellar cistern and floor of the third ventricle

She was started on levothyroxine and hydrocortisone replacement. She underwent transfrontal craniotomy. During surgery, the lesion was seen to be compressing the optic chiasm and reached up to the floor of the third ventricle. Subtotal excision of the sellar-suprasellar mass was performed. Histopathological examination confirmed the lesion to be an adamantinomatous craniopharyngioma (Figure 3). Post-surgery her nystagmus resolved over a period of one month. However, she developed central diabetes insipidus and required additional desmopressin replacement. When followed-up at three months, she was nystagmus-free. Her uniocular distance visual acuity, visual field and fundus appearance however remained unchanged. Repeat MRI showed a 1.8 × 1.7 × 1.3 cm residual lesion still compressing the optic chiasm for which she is planned for intensity-modulated radiotherapy.

Figure 3.

Photomicrograph showing islands of squamous epithelium with peripheral palisading, central stellate reticulum (black arrow) and the presence of wet keratin (blue arrow), suggestive of adamantinomatous craniopharyngioma (haematoxylin and eosin, x200)

Discussion

First reported by Maddox in 1914,¹ see-saw nystagmus is characterised by cyclical movement of the eyes manifesting clinically as intorsion and elevation of one eye and simultaneous extorsion and depression of the other eye. The resulting waveform can be either pendular or jerk, otherwise referred to as see-saw and hemi-see-saw nystagmus, respectively.² The mechanism of this form of nystagmus is yet to be fully elucidated.³ However, the hitherto available evidence supports the fact that pendular-waveform see-saw nystagmus usually results from a midline meso-diencephalic bilaterally compressing lesion (as in the index case). The jerk-waveform variant, on the other hand, is mostly the result of a unilateral lesion in the meso-diencephalic junction.²

Two-third of the patients with pendular see-saw nystagmus have suprasellar/parasellar lesions that compress the meso-diencephalic region.^3–5 Amongst them, the most commonly encountered lesions are craniopharyngiomas and giant pituitary adenomas.^3,4,6 Damage to the interstitial nucleus of Cajal, located in the meso-diencephalic region adjacent to the medial longitudinal fasciculus, has been implicated in the pathogenesis of pendular see-saw nystagmus.³ Fibres from the interstitial nucleus of Cajal project to the oculomotor and trochlear nuclei as well as to the vestibular nuclei and spinal cord. Damage to the interstitial nucleus of Cajal itself or its projections may lead to unstable visuo-vestibular control resulting in see-saw nystagmus. Earlier it was believed that disturbance in vision alone may be sufficient for the genesis of see-saw nystagmus^7,8; however, the present belief is that visual loss need not be present. This is exemplified by the occurrence of see-saw nystagmus in patients with isolated medullary and cerebellar lesions with normal vision.^9,10 Other rare causes of see-saw nystagmus include multiple sclerosis,¹¹ head injury,¹² brainstem stroke,⁹ whole brain radiation, intrathecal methotrexate therapy¹³ and certain congenital causes like achiasma, hemichiasma,¹⁴ Arnold-Chiari malformation¹⁵ and platybasia.¹⁰

Craniopharyngiomas are rare embryonic malformations of the sellar and parasellar area accounting for 1.2–4% of all childhood intracranial tumours. In children and adolescents, the adamantinomatous variant predominates. Over 90% of craniopharyngiomas have a suprasellar component. Symptoms result from mass effect of the lesions leading to non-specific manifestations of raised intracranial pressure (nausea and vomiting) along with visual impairment and anterior pituitary hormone insufficiencies.¹⁶ Around 50% of patients with craniopharyngiomas present with ocular symptoms consequent to optic atrophy, papilloedema and concomitant squint.¹⁷ Craniopharyngiomas presenting as see-saw nystagmus are extremely unusual. In our index case, the lesion was extending up to the floor of the third ventricle probably causing bilateral compression of the meso-diencephalic region resulting in pendular see-saw nystagmus. Transcranial subtotal excision led to a reduction in the size of the lesion and decompression of the mesodiencephalic region, resulting in resolution of the nystagmus.

Declaration of interest statement

The authors declare that they have no conflicts of interest.

Patient consent and ethics statement

Written informed consent was obtained from the patient’s father.

Supplemental data

Supplemental data for this article can be accessed on the publisher’s website.