Frameless Gamma Knife Radiosurgery with Leksell ICON: Initial Experience.

Gamma knife radiosurgery saw the light of the day when the Swedish physician "Lars Leksell" postulated the salient first principles of stereotactic radiosurgery. Prior to being realized in its new 'avatar' "The ICON", Leksell Gamma Knife (LGK) "Perfexion" has been the most practiced model and is still in practice in most of the centers in India. The Gamma Knife ICON (the sixth generation model) utilizes the concept of the Cone-Beam Computed Tomography (CBCT) module, thus allowing non-invasive immobilization of the skull employing frameless treatments without jeopardizing accuracy to sub-millimeters. The LGK ICON however has the same stereotactic delivery and patient positioning system as Perfexion and mesmerizes the care givers with the added technically sound feature of the CBCT imaging arm, that is, CBCT and an intra-fraction motion management system. The experience with ICON on both the sub-sets of patients has been intriguing and awe-inspiring. Despite its challenges of being detected with significant intra-fraction errors, we realized that the non-invasive thermoplastic mask fixation system has its own set of specific characteristics: fairly simple dosimetry; short radiation delivery times; and calm, composed, co-operative patients. We have been successful in conducting frameless gamma knife surgeries in ~25% of patients planned for gamma knife surgery. We look forward to witness this avant-garde pioneering scientific automation being practiced in a higher number of patients.

Simplifying Tumor Volume Estimation from Linear Dimensions for Intra-Cranial Lesions Treated with Stereotactic Radiosurgery.

AIMS: This study aims to derive simple yet robust formula(s) for the calculation of cranial tumor volume using linear tumor dimensions in anterioposterior (AP), mediolateral (ML) and craniocaudal (CC) directions and also propose a reproducible methodology for tumor dimension measurements. MATERIALS AND METHODS: Magnetic resonance images (MRI) of 337 patients planned for Gammaknife Stereotactic Radiosurgery for different types of brain tumors were analyzed using Leksell Gamma Plan (LGP) software. Tumor volume in three dimensional was outlined and maximum tumor diameters were measured in three orthogonal directions AP, ML, and CC on the MRI. Formulas were derived to calculate tumor volume from AP, ML, and CC diameters using linear regression technique. An agreement between the calculated volume and standard volume observed from LGP software was determined using Bland Altman (B-A) plot. A comparison was made between the volume calculated using traditionally used formula of ellipsoid, standard volume obtained from LGP software and volume calculated from formulas derived in the present study. RESULTS: The tumors were divided into two categories based on their size for better volume prediction. The tumors having product of their diameters in the range 0-2.5cc were called "small tumors" and the formula proposed for their volume estimation (V = 1.513) × (AP × ML × CC) + 0.047 ) was found to predict the tumor volume with an average bias of 0.0005cc. For "large tumors," having product of diameters in the range 2.5-36cc, the proposed formula (V = 0.444 × (AP × ML × CC) + 0.339 ) predicted the tumor volume with an average bias of 0.007cc. CONCLUSIONS: The two formulas proposed in the study are more accurate as compared to the commonly used formula that considers the tumors as ellipsoids. The methodology proposed in the study for measurement of linear tumor dimensions is simple and reproducible.

Microvascular Clipping of A1 Segment Aneurysms.

BACKGROUND: Aneurysms arising from the proximal segment (A1) of the anterior cerebral artery (ACA) are relatively rare. Because of their small size, abnormal location in relation to the parent artery and the risk of damage to the surrounding perforators, their surgical management is a big challenge. We present our experience with 7 patients of A1 segment aneurysms. SETTINGS AND DESIGN: Tertiary care referral center. MATERIALS AND METHODS: Seven patients who were diagnosed with A1 aneurysms between 2009 and 2017 were included. Preoperative evaluation included Non-Contrast Computed Tomography (NCCT) head and angiography (Digital Subtraction Angiography with/without CT-Angiography). The clinicoradiological condition of the patients was graded as per World Federation of Neurological Surgeons (WFNS), Fisher and Hunt and Hess (H and H) Grading systems. A retrospective review of clinical features, radiological descriptions, surgical treatment, and outcomes was done. RESULTS: All patients underwent microneurosurgical clipping. All aneurysms were saccular, ranging in size from 4 to 14 mm and neck size varied from 2 to10 mm. Most aneurysms 5 (71.4%) had a posterior direction. Anatomical variations were noticed in 3 (42.8%) patients. Posteroinferiorly directed aneurysms were difficult to clip. As per Glasgow Outcome scale (GOS), 6 (85.7%) patients had a good outcome, whereas 1 (14.2%) had poor outcome. As per the modified Rankin Scale (mRS) too, 6 (85.7%) had a favorable outcome. There were no deaths. CONCLUSION: A1 aneurysms are frequently associated with vascular anomalies and generally rupture when small. A1 aneurysms with a superior and anterior direction are relatively easy to clip whereas those directed postero-inferiorly are difficult. Close association with critical perforators also compounds the situation. Due to the rarity of A1 aneurysms, large series are few in literature.

Optic Tract Edema: A Rare Entity in Pituitary Macroadenoma.

Pituitary tumors are relatively common tumors accounting for almost 15% of all primary brain tumors. Pituitary macroadenomas cause mass effect on the optic apparatus causing a myriad of visual deficits. On imaging generally the anterior visual pathway is involved which may be compressed by the mass lesion. Edema in the posterior visual pathway, i.e., optic tracts on magnetic resonance imaging is a relatively common finding in craniopharyngiomas and other metastatic lesions in the pituitary region. Edema in the optic tracts in pituitary macradenomas is a very rare entity as reported by various authors in literature. We report a case of optic tract edema in a case of pituitary macroadenoma which caused rapid deterioration in the vision of the patient and improved after administration of steroids.

Impact on Cognitive Improvement Following Burr Hole Evacuation of Chronic Subdural Hematoma: A Prospective Observational Study.

OBJECTIVE: Patients of Chronic subdural haematoma can present with only subtle cognitive impairment without any motor deficit. It is hence imperative for the treating clinician to be aware of this entity. The aim of the study was to identify any statistically significant improvement of cognitive functions following burr hole evacuation of Chronic SDH especially in the elderly patients. METHODS AND MATERIAL: A Prospective observational study of 30 patients of CSDH, from Jan 2015 to Dec 2016 was done at a tertiary level Armed Forces Hospital. The study had 23 male, 07 female, with age ranging from 7-85 years. The cognitive function of each patient was assessed at admission and 24 hours after surgery by MMSE. Radiological confirmation was done by CT head. Standard two burr holes were made and hematoma evacuated. The clinical, cognitive assessment and radiological data were collected and analysed. RESULTS: There was no statistical significance preoperatively between age and pre operative cognitive impairment, headache, hemiparesis, dysarthria (P>0.05). We however found a statistically significant improvement postoperatively in cognitive impairment, headache (P= 0.00), motor deficit (P=0.01) and dysarthria (P=0.046). CONCLUSION: The clinical features of dementia and other neurodegenerative disorders simulate CSDH in the geriatric population. These patients should have early neuroimaging and prompt surgical intervention to alleviate cognitive deficits.

Spastic quadriparesis due to pathological fracture of odontoid secondary to carcinoma prostate: A rare presentation.

Prostate carcinoma presenting as symptomatic metastases to atlantoaxial spine is extremely rare. Spastic quadriparesis due to pathological fracture of odontoid as the only initial manifestation without symptoms of primary malignancy is rarer still. We report a 64-year-old male who presented with progressive spastic quadriparesis along with urinary retention of 3 weeks duration. Computed tomography and magnetic resonance imaging cervical spine and craniovertebral junction showed type III pathological fracture of odontoid with anterior translation of C1 with spinal cord compression. Biopsy from an enlarged prostate showed adenocarcinoma of prostate. The patient was managed conservatively from neurological aspect as he refused for any surgical intervention.

Nelson's syndrome presenting as bilateral oculomotor palsy.

Nelson's syndrome refers to a clinical spectrum arising from progressive enlargement of pituitary adenoma and elevated adrenocorticotrophic hormone after total bilateral adrenalectomy for Cushing's disease comprising of hyperpigmentation, visual field defects which can be life threatening. We report here a 50-year male presenting with rapid onset of Nelson's syndrome with an unusual finding of bilateral oculomotor palsy mistakenly treated as ocular myasthenia.

Post-traumatic cervical pneumorrhachis--a rare entity.

Pneumorrhachis(PR) is a rare phenomenon and post traumatic PR even more so. Presentation can vary from asymptomatic to significant neurological deficit and so the management has to be individualised. We present a case of post-traumatic cervical PR.

Primary spinal pleomorphic xanthoastrocytoma.

Pleomorphic xanthochromic astrocytoma primarily of the spinal cord is a rare entity. The case is possibly the fifth such report. Complete surgical excision is the essential requirement for good survival. In the absence of any clearly laid down protocols of adjuvant treatment, anecdotal reports support treatment with chemotherapy alone or both chemotherapy and radiotherapy.