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|Year : 1999 | Volume
| Issue : 2 | Page : 148-51
Suprasellar arachnoid cyst presenting with precocious puberty : report of two cases.
Gupta SK, Gupta VK, Khosla VK, Dash RJ, Bhansali A, Kak VK, Vasishta RK
Departments of Neurosurgery, Endocrinology and Pathology, Postgraduate Institute of Medical Education and Research, Chandigarh, 160012, India.
Departments of Neurosurgery, Endocrinology and Pathology, Postgraduate Institute of Medical Education and Research, Chandigarh, 160012, India.
Suprasellar arachnoid cysts (SSAC) are uncommon intracranial lesions. Two patients of SSAC presenting with precocious puberty are described. In both the cases partial excision of the cyst wall, through a pterional craniotomy, establishing communication with the basal subarachnoid spaces was carried out. The endocrinological symptoms regressed after surgery. The clinical presentations of SSAC and the treatment options available are reviewed.
|How to cite this article:|
Gupta S K, Gupta V K, Khosla V K, Dash R J, Bhansali A, Kak V K, Vasishta R K. Suprasellar arachnoid cyst presenting with precocious puberty : report of two cases. Neurol India 1999;47:148
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Gupta S K, Gupta V K, Khosla V K, Dash R J, Bhansali A, Kak V K, Vasishta R K. Suprasellar arachnoid cyst presenting with precocious puberty : report of two cases. Neurol India [serial online] 1999 [cited 2019 Apr 22];47:148. Available from: http://www.neurologyindia.com/text.asp?1999/47/2/148/1632
Arachnoid cysts are intra-arachnoidal collections of cerebrospinal fluid (CSF) and account for 1% of all traumatic intracranial mass lesions. These are commonly of congenital origin. Neurological deficit is produced through expansion, local compression and obstruction to the flow of CSF. Suprasellar arachnoid cysts (SSAC) are uncommon lesions, accounting for 9% of all intracranial arachnoid cysts., Inspite of an increase in the number of cases reported, following the advent of computerised tomography (CT), their symptomatology and treatment remains controversial. Although the exact incidence of precocious puberty in SSAC is uncertain, it is an uncommon presentation with only sporadic reports in the literature.,,,, Two cases of SSAC presenting with precocious puberty are reported along with review of literature.
Case No.1 : A 10 year old boy presented with complaints of change in voice and an abnormal increase in the size of external genitalia over a period of 6 months. There was no history of associated headache, vomiting or visual disturbances. His height was 120 cm (expected 137cm) and weight 26.5 kg (expected 31.4 kg). He had a deep voice; axillary and pubic hair of A1/P3 (Tanner's grade 3) [Figure 1] and a testicular volume of 5 ml on each side. Both the testes were firm in consistency.
Plain X-rays of the skull were normal. CT scan demonstrated a nonenhancing hypodense, cystic suprasellar lesion with mild hydrocephalus. MRI showed a suprasellar lesion, which was hypointense on T1 weighted image and hyperintense on T2 weighted images [Figure 2]. The MR signal intensity was similar to that of CSF. Endocrinological profile revealed increased levels of luteinizing hormone (LH)-6.5 mlU/ml, follicular stimulating hormone (FSH)-1.25 mlU/ml with normal levels of prolactin (PR) 1100 mlU/ml, testosterone - 1.5 nmol/litre, T3-1.7 ng/ml and T4 -96 ng/ml.
A pterional craniotomy with partial excision of the cyst wall was done. Communication with the basal subarachnoid cisterns was established. The histopathological report confirmed the diagnosis of an arachnoid cyst[Figure 3]. The secondary sexual characters gradually regressed postoperatively.
Case No.2 : An eight year old boy was admitted with history of repeated attacks of giddiness for the past 3 months. During each episode, which lasted 5-7 minutes, the child would fall down. There was no loss of consciousness, headache, vomiting or diminution of vision. CT scan showed dilated lateral and 3rd ventricles. A diagnosis of aqueductal stenosis was made and a right VP shunt was put in. The patient was readmitted 3 months later with headache, vomiting, anorexia and malnutrition of 10 days duration. Repeat CT Scan showed dilated lateral and 3rd ventricles. Shunt revision was performed and the patient was discharged. The child presented again at the age of 9 years with deep voice and, enlargement of external genitalia. He had axillary and pubic hair of A1P4 (Tanner's grade 4), and a large testicular volume of 6ml on each side. The child was malnourished. His height was 117 cm (expected 127 cm) and weight 18.2 kg (expected 20.2 kg). A metrizamide CT was done which showed a suprasellar cystic lesion not communicating with the ventricles. The diagnosis of a suprasellar arachnoid cyst was made. Endocrinological investigations revealed increased levels of LH 6.5 mlU/ml, FSH-1.225 mlU/ml, testosterone 3.9 nmol/lit and normal levels of T3 (0.58 ng/ml) and T4 (55 ng/ml). A right frontal craniotomy and partial excision of the cysts wall was done, communicating the cyst with the basal subarachnoid spaces. Biopsy was confirmatory of an arachnoid cyst. Postoperatively there was minimal regression of the secondary sexual characters. The patient was put on medroxyprogesterone acetate (MPA)(100 mg i.m. monthly) to arrest the progression of secondary sexual characters.
Arachnoid cysts probably arise as a result of anomalous splitting and duplication of the endomeninx during the neural tube folding. Light and electron microscopic studies have conclusively demonstrated that arachnoid cysts are intra-arachnoidal lesions, their outer and inner walls consisting of sheets of arachnoid cells, that join with normal arachnoid at the cyst margins., Suprasellar arachnoid cysts (SSAC) are thought to develop from an anomaly of the Liliequist's membrane, either as a diverticulum, or from a split within the membrane and secretion of CSF within the cavity., This diverticulum could increase in size following inflammatory, haemorrhagic or developmental events., Alternatively a ball valve like mechanism may allow ingress but not egress of CSF from the cyst. Free communication between the subarachnoid space and the cyst has been reported in several cases.,,
About 100 cases of SSAC have been described in sufficient detail in the French and English literature., Clinical manifestations include signs of obstructive hydrocephalus, visual impairment, endocrine dysfunction, gait ataxia and `bobble-head doll' syndrome. SSAC may also remain asymptomatic and be discovered incidently. Endocrine dysfunction can occur in the form of precocious puberty, amenorrhoea, developmental delay, skeletal growth retardation and hypothalamic disturbances. The frequency of this dysfunction is not well defined. Of the total 54 cases of SSAC reviewed by Hoffman et al in 1982, only eight had features of precocious puberty (14.8%). In the largest series of SSAC, 4 cases (out of 20) had precocious puberty. Brauner et al analysed 6 cases of precocious puberty secondary to SSAC. The pathogenesis of precocious puberty in SSAC is debatable. It is known that tumours and other pathological processes involving the hypothalamus frequently modify sexual development. These lesions may destroy the posterior hypothalamus leaving the anterior hypothalamus intact. The intact anterior hypothalamus in the absence of inhibitory influences, leads to increased pituitary function. The preoptic region possibly plays an important role in regulating the release of gonadotropic hormones from the anterior lobe of hypophysis. In rats, this region has been termed as the `sexually dimorphic nucleus of the preoptic area'. According to Styme, inhibitory tone develops within the central nervous system after birth which reduces the gonadotropin levels preventing early pubertal development. It is postulated that this neural inhibition may be interrupted by hypothalamic hamartomas leading to precocious puberty. A similar explanation may hold true for SSAC associated with precocious puberty.
On CT scan, the SSAC appears as a hypodense extra-axial lesion, of CSF density, that does not enhance after contrast. Its border is clearly defined, smooth and may be rounded or linear.,, Studies of CSF fluid using radionuclide or iodinated contrast agents have been used to differentiate between communicating and noncommunicating cyst or to differentiate SSAC from a dilated 3rd ventricle., MRI scanning has obviated the need for invasive neuroradiological intervention.
There is no consensus as to the operative procedure of choice in SSAC. Different treatment preferences include a subfrontal fenestration of the cyst into the basal cisterns,M a transcallosal fenestration of the cyst into the lateral ventricles with an optional ventriculoperitoneal shunting, cystoperitoneal shunt and a percutaneous ventriculocystostomy. There is a significant incidence of reoperation, irrespective of the initial procedure. The establishment of a single CSF space, by surgically communicating the cyst with the ventricular system or basal cisterns, appears to offer the best chance of a success in the treatment of SSACs. A shunt may still be required in an occasional hydrocephalic patient.
There are a few reports of regression of endocrine disorders with different treatment modalities.,,, Sugawara et al reported an infant with SSAC presenting with precocious puberty which eventually disappeared after a cysto-peritoneal shunt. The evolution of precocious puberty in the study by Brauner et al varied from one case to another, without any relation to the quality of control of the arachnoid cyst or the associated hydrocephalus. None of the patients treated by Pierre Kahn et al had regression of their endocrine symptoms. The persistence or post-operative development of these disturbances could be attributed to hypothalamic damage secondary to ventriculocystostomy. Two of the 5 patients of SSAC managed by cyst wall resection developed raised prolactin levels following surgery. Both these patients had a transcallosal drainage of the cyst possibly causing hypothalamic damage.
Both the patients being reported responded well after partial excision of the cyst wall and establishing a communication between the cyst and the basal subarachnoid space. In case 1, there was significant regression of the characters of precocious puberty, while case 2 had minimal regression and was given MPA to which he responded satisfactorily. This technique obviates the risk of damage to the hypothalamic region and could be responsible for the favourable clinical response.
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