Suprasellar arachnoid cyst presenting with bobble-head doll syndrome: Report of three cases.

Suprasellar arachnoid cysts can have varied presentations with signs and symptoms of obstructive hydrocephalus, visual impairment, endocrinal dysfunction, gait ataxia and rarely bobble-head doll movement. The bobble-head doll movement is a rare movement disorder characterized by antero-posterior bobbling of the head and neck on the trunk every 2-3 seconds. We present three cases with bobble-head doll syndrome associated with a large suprasellar arachnoid cyst and obstructive hydrocephalus, which were treated with endoscopic cystoventriculocisternostomy and marsupialization of the cyst.

Introduction

Bobble-head doll syndrome (BHDS) was first described by Benton et al. in 1966 in association with suprasellar arachnoid cyst with obstructive hydrocephalus.[1] BHDS is a rare movement disorder usually due to cyst in the region of third ventricle and less often due to choroid plexus papilloma, craniopharyngioma, aqueductal stenosis, colloid cyst, cyst in cavum septum pellucidum and cavum inter positum.[2]

Case Reports

Case 1

A 10-month-old female child brought by parents with H/O two episodes of generalized tonic clonic seizures, with involuntary bobbling of head over trunk since 1-month, On evaluation magnetic resonance imaging (MRI) showed well marginated cerebrospinal fluid (CSF) signal intensity cystic lesion in prepontine, interpeduncular, suprasellar, anterior third ventricle with moderate dilatation of third and both lateral ventricles [Figure 1]. She underwent right frontal burr hole, endoscopic partial excision and marsupialization of cyst, third ventriculostomy, and septostomy. Intra-operatively large arachnoid cyst was seen bulging into the foramen of Monro. Postoperative period was uneventful, no further episodes of seizures or involuntary bobbling of head. Follow-up MRI [Figure 2] done after 4 years revealed significant decrease in cyst and resolution of hydrocephalus possibly due to early presentation and interventions, allowing developing brain to expand.

Figure 1

T1-weighted images coronal: Well-defined cerebrospinal fluid signal intensity in prepontine, interpeduncular, suprasellar, anterior third ventricle with dilatation of third and both lateral ventricles

Figure 2

T1-weighted images axial: Well-marginated cerebrospinal fluid signal intensity cystic lesion in prepontine, interpeduncular, suprasellar, anterior third ventricle with moderate dilatation of third and both lateral ventricles

Case 2

A 8-year-old right handed female child presented with H/O high grade fever on and off for 2 months, H/O difficulty in walking, abnormal head movements for 1 month and one episode of generalized tonic clonic seizures. Child has bobbling of head back and forth which aggravated with walking and minimally relieved with rest. Child had difficulty in walking and walks with broad based gait. Her computed tomography (CT) and MRI brain was suggestive of large third ventricular arachnoid cyst with mass effect over the brain stem and obstructive hydrocephalus [Figures 3 and 4]. She underwent right frontal burr hole, endoscopic cysto ventriculostomy, third ventriculostomy and reservoir placement. Cyst was bulging into the foramen of Monro; it was thick, tough, vascular, adherent to ventricular wall and stretching the third ventricular floor and anterior wall [Figures 5 and 6]. Postoperatively she had minimal head bobbling and broad based gait, which gradually reduced on follow-up.

Figure 3

T1-weighted image axial: Ventricular dilatation has significantly decreased with near normal size ventricles

Figure 4

T2 sagittal: Gross dilatation of body of lateral and third ventricle with fenestrations of cyst at superior and inferior aspect

Figure 5

Cyst bulging into foramen of monro

Figure 6

Thinned out third ventricular floor

Case 3

A 4-year-old female girl presented with involuntary nodding of the head back and forth, ataxia on walking since 1-year. Nodding of the head started insidiously, gradually progressed and aggravated since last 3 months. Head nodding was more pronounced on walking and absent during sleep. Her head circumference was within normal limits. Her social, behavioral and language development were normal. Her routine hematological and endocrine parameters were normal. CT scan brain plain showed marked dilatation of lateral ventricles and third ventricles with a normal fourth ventricle [Figures 7 and 8]. MRI showed large suprasellar arachnoid cyst in third ventricle with compression of fornix, corpus callosum with enlarged lateral and third ventricles. She was taken up for surgery, right frontal burr hole, endoscope marsupialization of the cyst, cysto ventriculostomy, and third ventriculostomy. Intra-operatively cyst was bulging into the foramen of Monro, thick walled blue color, obstructing the aqueduct of sylvius. Third ventricular floor, lamina terminalis was completely thinned out exposing naked basilar and B/L anterior cerebral arteries respectively. CSF was under low pressure. Postoperatively head nodding completely disappeared.

Figure 7

Computed tomography scan: Cerebrospinal fluid cystic lesion noted in suprasellar, prepontine, interpendicular, third ventricle with moderate obstructive hydrocephalus. Normal fourth ventricle

Figure 8

Minimal decrease in cerebrospinal fluid density cystic lesion and obstructive hydrocephalus

Discussion

Arachnoid cyst account for 1% of all intracranial lesions and 9% of these are suprasellar.[3] Sellar region arachnoid cysts are classified into suprasellar and intrasellar cysts. Suprasellar arachnoid cysts are the most common type. Suprasellar arachnoid cyst are common in children <5 years and there is a male predilection.[3]

Pathophysiology of arachnoid cysts remains unclear. Various theories have been proposed regarding their formation. One of the theory proposes that during early embryonic development cysts occur as a result of splitting of the arachnoid membrane. Others said that arachnoid cysts enlarge due to either a secretory mechanism of the arachnoid cells or as a result of a “ball-valve” mechanism, allowing fluid into the cyst but blocking its outflow.[4] Schroeder and Gaab clearly identified a slit valve-like structure formed by an arachnoid membrane around the basilar artery that opened and closed with arterial pulsation.[5] Suprasellar cysts are uncommonly associated with chiari malformation and syringo hydromyelia.[6]

Among varied presentations of suprasellar arachnoid cyst, it rarely presents as BHDS. BHDS is characterized by rhythmic back and forth nodding of head and neck on trunk, at times side to side movements. Exact pathophysiological mechanism causing BHDS is unclear. Several mechanisms have been proposed - an extra pyramidal dysfunction, thalamic dysfunction,[7] red nucleus and its connections dysfunction. Wiese et al. showed it as a learned behavior through which patient can reduce the size of the cyst with intermittent emptying. His observation was supported by serial metrizamide CT cisternography and documented decrease in size of cyst with bobbling movements.[8]

Suprasellar arachnoid cysts are rare lesions, and their optimal management is still controversial. The aim of surgical treatment is to a restore a permanent communication between cystic cavity and the intraventricular or/and subarachnoid space to normalize CSF flow. Various treatment options are available - craniotomy and fenestration of cyst or sub frontal endoscopic assisted fenestration of the cyst, trans callosal fenestration of cyst, cysto-peritoneal shunt, percutaneous ventriculostomy, combined stereotaxy using neuro navigation and endoscopic fenestration of cyst.[9] Among the different surgical measures available, approach should be selected on an individual case basis. Endoscopic marsupialization of cyst with establishment of single CSF space by surgically communicating cyst with ventricles and basal cisterns are the preferred technique.

Conclusion

Suprasellar arachnoid cyst with BHDS is extremely rare. Surgical fenestration of cyst results in complete and permanent disappearance of bobbling movements. Endoscopic fenestration with cystoventriculocisternostomy is safe, effective and less invasive technique.