The present study on the surgical outcome of subtypes of infra-tentorial space brain tumors in children and adults observed that about 1/3rd (31.7%) patients were children (18 years. and below). Histopathologically, malignancy featured in most, (54.1%), of the patients while benign tumors occurred in 45.8% patients (Tables 1 and 2). A research study in 1997 revealed that out of the 1000 vestibular schwannoma tumors operated in 962 patients, 2.1% patients had residual tumors; 1.1% patients had severe neurological disability; 5.5% patients had caudal cranial nerve palsies, and 1.1% had mortality [2]. Seol et al. in 2006 analyzed 116 patients of vestibular schwannomas where residual tumor was seen in 77.5% and the recurrence in 17.2%. The gross total resection was the best approach to avoid the recurrence [3]. Yamakami et al. in 2004 revealed 14% residual tumor, 4% neurodeficit, and no mortality in 50 operated patients of vestibular schwannomas [4]. The present study observed 50% residual tumors in trigeminal schwannomas and 23.4% in vestibular schwannomas. About 2.9% schwannomas were found in children. Roberti et al. 2001, wrote that a hundred and sixty one patients of infra-tentorial space meningiomas were operated over a period of 9 years with residual tumors found in 43% patients; progression of disease and recurrence in 13.7% and mortality was found in 2.5% patients [5]. The researchers in 2012 showed postoperative results of 64 patients of infra-tentorial space meningiomas, where recurrence occurred in 15.6% patients, severe neurological deficits in 33%, hydrocephalus in 43.75% patients, and mortality in 3.2% [6]. Hakuba et al. reported 17% mortality and severe neurological deficits in 83% patients in radical excision of clival meningiomas of infra-tentorial space [7]. Couldwell et al. studied 40 males and 69 females, a male female ratio of 1:1.7, with infra-tentorial space (petro-clival) meningiomas postoperatively in which gross total excision was achieved in 69% of the patients, 13% had recurrence or progression of disease [8]. Louis et al. reported a 5-year progression-free survival of approximately 50% [9]. The present analysis of meningiomas showed almost similar results (Tables 1 and 2). Hemangioblastomas are uncommon, highly vascular, well-circumscibed, less than 3% of all CNS tumors and mostly (7.5%) in adult cerebellum and brainstem [10]. The present study found an incidence of 6.8% for hemangioblastomas, including two sisters in a family, with an event-free survival (EFS) of 85.7%. Dermoid cysts represent a rare clinical entity that accounts for 0.1–0.7% of all brain tumors [11]. This study observed that the dermoids comprised 3.6% of all the infra-tentorial space tumors of the brain. The EFS of dermoids was 100%. Epidermoids, also known as cholesteatomas, are pearly tumors and account for approximately 0.1% of all intra-cranial tumors growing by the desquamation of the cyst wall and accumulation of keratin and cholesterol [12]. Zakrzewski et al, studied 216 children with infra-tentorial space tumors below 18th year of age, which depicted male/female ratio of 1.35:1.00. The commonest tumor subtype was pilocytic astrocytoma in 41.5% patients; medulloblastoma in 34.5%; ependymomas 13%, and mixed neuronal-glial tumors in 5.5% patients [13]. Muzmdar D et al. in 2011, while presenting 154 patients (age < 18 years) of Medulloblastoma noted that 92.2% (142 cases) had classical medulloblastomas and 5.1% (8 cases) had desmoplastic variant. The 5-year and 10-year progression-free survival rate was 73% and 41% respectively for average risk disease while for high risk disease, it was 34% [14]. Rutka 1997 noted that medulloblastomas are intra-cranial childhood neoplasm, accounting for 25% of all childhood tumors [15]. Also, Bloom and Bessell in 1990 showed that medulloblastomas in adults account for < 1% of all adult brain tumors [16]. Chan et al. in 2000 found in a study that the recurrence rate for medulloblastomas in adults is approximately 50% to 60%. The median time-to-tumor progression (TTP) and recurrence is approximately 30 months after treatment [17]. In the present study medulloblastomas (Figs. 4 and 5) were found in 17.5% patients, mostly (84.7%) in children. The postoperative residual tumor was found in 43.0% and recurrence in 19.4%. There occurred a mortality of 30.5%. Djalilian and Hall (1998) reported that 53% patients in a study had grade IV malignant cerebellar gliomas and 47% anaplastic (grade III) astrocytomas [18]. The present study observed that 11.4% infra-tentorial brain tumors had high-grade anaplastic and glioblastoma type of malignant cerebellar astrocytomas. The postoperative residual tumor was found in 70.2% and a EFS of 31.9% was observed with a mortality of 2.1%. Witt et al. 2011 reported that the posterior fossa ependymomas comprise two distinct molecular entities, ependymoma posterior fossa A (EPN PFA) and ependymoma posterior fossa B (EPN PFB), with differentiable gene expression profiles [19]. In the present study, ependymoma of the 4th ventricle (Fig. 4) had residual tumors in 41.8% and recurrence in 11.6%. The EFS of 51.1% and a mortality of 6.9% were observed. Desai et al. 2001, reported that the pilocytic cerebellar astrocytomas comprise 25% of all infra-tentorial brain tumors in children [20]. Follow-up of 104 children with cerebellar juvenile pilocytic astrocytomas over a mean period of 8.3 years, Daszkiewicz et al. 2009, found that 57.6% (60/104) patients had permanent neurological deficits while 47 had significant behavioral disorders [21]. A study by Lesniak et al. 2003 observed that among 57 patients of brainstem gliomas, 29 had a total surgical resection, 8 a near total resection (> 90% resection), 15 a subtotal resection (50–90% resection), and 5 a partial resection (< 50% resection). The progression-free survival of all patients was 71.9% at 3 years and 45.6% at 5 years [22]. Donalson et al. 2006 reported high rate of recurrence or progression which often follows an inexorable course of progression, despite chemo/radio therapy [23]. All brainstem gliomas in present study had postoperative residual lesions and 37.5% had progression of disease and 56.2% had recurrence. The severe disability in the brainstem gliomas, like pontine gliomas (Fig. 5), in present study, was more often linked to the long survival, motor dysfunction, decubitus ulcers, and respiratory system infections caused by the early involvement of lower cranial nerves and the long tracts by these low-grade tumors subtypes. The brain stem gliomas had a mortality of 43.7% and an EFS of 31.2%. Sunderland et al. 2016 reported that overall 80% patients underwent gross total resection (GTR), 14 % subtotal resection (STR) and 6 % underwent biopsy of metastatic deposits of infra-tentorial space contents. The median overall survival (OS) was 6.00 months. The 28 day mortality was 7.6 % (n = 7) with a peri-operative morbidity of 22.8 % (n = 21) [24]. Zhang et al. 2012 observed that the most common primary site of malignancy for brain metastatic deposit was lung (20–40 %) followed by breast (5–17 %) and melanoma (7–11 %) with renal, colorectal, and gynecological cancers making up the majority of the remaining [25]. The present series of 410 infra-tentorial brain tumors consisted of 2.1% patients of metastatic deposits (Fig. 2), mostly from primaries like carcinoma lung, breast, renal cell carcinoma and malignant melanoma. Tate et al. in 2012 suggested an increase in survival of pineoblastomas with increasing degrees of resection by observing 5-year survival rate of 84% for patients who underwent gross total resection versus 53% for patients who underwent subtotal resection and 29% for patients who underwent debulking [26]. Pineoblastomas (Fig. 6) in this study comprised 1.7% of all infra-tentorial brain tumors while 57.1% of these were children. Roberti et al. 2001 reported 5% malignant meningiomas in a study of 161 patients [5]. However, Wang et al. 2016 reported that about 51% patients experienced recurrences. The relapse-free survival at 12 months was 84.3% and at 5 years was 57.8% [27]. Of 410 infra-tentorial space brain tumors presently, 0.97% had malignant meningiomas (WHO grade III), mostly rhabdoid and anaplastic, which formed 10.6% of all infra-tentorial tumors with a recurrence of 100% and mortality of 75.0%.

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