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Neurology India, Vol. 51, No. 3, July, 2003, pp. 407-409 Suprasellar arachnoid cyst presenting with bobble-head doll movements: A report of 3 cases Desai KI, Nadkarni TD, Muzumdar D, Goel A Correspondence Address: Code Number: ni03134 ABSTRACT We report a series of three patients with suprasellar arachnoid cysts who presented with a rare bobble-head doll' syndrome. The abnormal head movements improved after surgical evacuation of the cysts in all the three cases. Various pathophysiological mechanisms involved in the bobble-head doll syndrome are discussed. The literature on suprasellar arachnoid cysts is briefly reviewed. INTRODUCTION Arachnoid cysts account for approximately 1% of all intracranial lesions.[1],[2] Suprasellar arachnoid cysts account for about 9% of all intracranial arachnoid cysts.[3],[4],[5] The association of abnormal bobble-head doll movements with suprasellar arachnoid cysts is rare but has been reported.[4] We report a series of 3 cases of suprasellar arachnoid cysts that presented with remarkably similar abnormal bobble-head doll movements. The pathophysiology of these abnormal movements in relationship to the suprasellar arachnoid cyst is discussed and the relevant literature is reviewed. CASE REPORT Three cases of suprasellar arachnoid cysts were treated in the Department of Neurosurgery, King Edward Memorial Hospital from 1995 to 2000. The age ranged from 2 to 5 years (mean - 3.3 years). All three were female patients. The duration of complaints ranged from 4 months to 6 months (average 5 months). The primary and predominant presenting clinical complaint was bobble-head doll movements. The movements in all the three patients were remarkably similar and comprised antero-posterior to-and-fro nodding movements of the head. The bobbling spell lasted from 30 seconds to 1 minute and could be stopped voluntarily or by tilting the head backwards. The movements began on leaning forwards. The movements were rhythmic at the frequency of approximately two times per second. There was no associated feature of raised intracranial pressure, abnormal behavior or any focal neurological deficits. Preoperative diagnosis of suprasellar arachnoid cyst was made in all three patients by computerized tomography (CT) scans and magnetic resonance imaging (MRI) scans [Figure-1a] & [Figure-1b]. The hormonal assay, which included serum T3, T4, TSH, prolactin and cortisol, was normal. In two patients, a sub-frontal route through a right basal frontal craniotomy was adopted. In one patient, the cyst was observed in the suprasellar space through the optico-carotid corridor. In the other patient, a translaminar approach was adopted to expose the cyst. The lamina terminalis was diaphanous and the blue-domed cyst was obvious through the thin lamina terminalis. In the third patient, the massive cyst was exposed through a transcallosal route. The cyst was encountered after incising the corpus callosum. The cyst contained clear CSF under moderately high pressure in each case. The cyst was widely marsupialized in each case so that it communicated freely with the subarachnoid space. Multiperforated sialastic tubes were strategically placed, communicating the cyst area to the cisternal spaces. The histological examination of the cyst wall in all the three patients revealed arachnoid cyst. The bobbling head movements stopped completely after surgery in all the three cases. The follow-up ranged from 6 months to 6 years with an average of 38 months. MRI scans done during the follow-up showed regression of the hydrocephalus and reduction in the size of the suprasellar arachnoid cysts. DISCUSSION The true incidence of intracranial arachnoid cysts is unknown because many may be asymptomatic throughout life.[6],[7] With the advent of CT and MRI the frequency of the diagnosis of arachnoid cyst has increased significantly. Congenital arachnoid cysts differ from secondary or false arachnoid cysts in that they are formed following inflammatory loculations of the CSF.[1],[2] The sellar region arachnoid cysts are divided into suprasellar cysts and intrasellar cysts. Suprasellar cysts are by far the more common type. Most suprasellar arachnoid cysts occur in children and there is a known male prevalence. The clinical manifestations of the suprasellar arachnoid cysts include symptoms and signs of obstructive hydrocephalus, visual impairment, endocrinal dysfunction and gait ataxia.[3],[4],[5] Endocrine dysfunction can occur in the form of precocious puberty, amennorhoea, developmental delay, skeletal growth retardation and hypothalamic disturbances.[8],[9] Chiari malformation, syringohydromyelia or rhinorrhoea are uncommonly associated with these cysts.[10],[11] Suprasellar arachnoid cysts rarely present with rhythmic to-and-fro bobbling of the head and trunk. Benton, in 1966, first described this abnormal movement as bobble-head-doll movement when describing children with third ventricular cyst.[12] There are many case reports of anterior third ventricle cysts presenting with bobble-head-doll movements. The association of suprasellar arachnoid cyst with bobble-head-doll movements is rare and there are isolated cases reported in the literature.[4],[13],[14],[15],[16],[17],[18],[19] The bobble-head-doll movement is a rare movement disorder characterized by 2 to 3 seconds antero-posterior bobbling of the head and neck on the trunk that is reminiscent of the movement seen in old-fashioned dolls with weighted heads at coil-spring necks. The movements become accentuated when the patient is upright and disappear when the patient is recumbent. The bobbling movement is suppressed during sleep or voluntarily by tilting the head backward. The syndrome of bobble-head-doll movements is commonly found in lesions which cause third ventricle dilatation.[20],[21] The common lesions are suprasellar arachnoid cyst, colloid cyst, aqeductal stenosis, craniopharyngioma and rarely, choroids plexus papilloma of the third ventricle.[16],[21] The exact pathophysiological mechanism of the bobble-head-doll movements caused by these lesions is unclear. Several theories about the mechanism of the unusual movement disorder are postulated. The cyst compresses the dorsomedial nucleus of the thalamus that occupies the paraventricular area. The polysynaptic pathways project from the dorsomedial nucleus of the thalamus to the midbrain tegmentum and red nucleus via the caudate nucleus and the putamen. The crossed and uncrossed rubrotegmentospinal and reticulospinal tracts descend to motor neurons in the cervical spinal cord, which innervate the neck muscles. Compression or intermittent pressure by the cyst on the dorsomedial nucleus stimulates these diencephalic extra-pyramidal pathways and results in bobbling movements of the head. The somatotropic motor pattern in the dorsomedial nucleus of the thalamus for the head and neck muscles is medial while that for the extremities and trunk is lateral. When compressed by an extremely large cyst, involuntary movements of the limbs also occur along with bobble-head-doll movements.[13],[20],[21] In contrast, Wiese and his colleagues suggested that head bobbling is a learned behavior, through which the patient is able to reduce the cyst size or relieve the ventricular dilation by rocking the cyst back and forth. Thus intermittent emptying of the cyst occurs. Wiese observed that the bobble-head phenomenon is often positional and can be temporarily suppressed by patients. He also concluded that bobbling movements ameliorate the headaches. He supported his theory by serial metrizamide CT cisternography studies and demonstrated a decrease in the size of the suprasellar arachnoid cyst by bobbling movements.[14] The various surgical options for treating the suprasellar arachnoid cyst include a sub-frontal fenestration of the cyst into the basal cisterns, a transcallosal fenestration of the cyst, cystoperitoneal shunt and percutaneous ventriculostomy.[4],[5],[22] Endoscopic marsupialization of the suprasellar arachnoid cyst by flexible or rigid endoscope is also described in the literature. There is a significant incidence of recurrence irrespective of the initial procedure.[23] The establishment of a single CSF space, by surgically communicating the cyst with the ventricular system or the basal cisterns, appears to offer the best chance of success in the treatment of the suprasellar arachnoid cyst. The syndrome of bobble-head-doll movements regressed completely after operation in all our 3 patients, clearly indicating the causal relationship. Literature review also supports this finding. It probably relates to the relieving of the compression of the dorsomedial nucleus of the thalamus, thereby breaking the abnormal excitatory extra-pyramidal circuit. To conclude, the association of bobble-head-doll movements in suprasellar arachnoid cysts is extremely rare. Surgical drainage of the suprasellar cysts offers an immediate, complete and permanent disappearance of these abnormal movements. REFERENCES
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