C1-C2 sagittal Cobb angle

C1-C2 sagittal Cobb angle

Cervical lateral radiograph; b Detail of 36-inch lateral radiograph showing measurements a. Occiput-C2 sagittal Cobb angle, b. Occiput-C7 sagittal Cobb angle, c. C1-C2 sagittal Cobb angle, d. C2-C7 sagittal Cobb angle, e. T1 tilt. Horizontal solid white line: C1-C7 Sagittal Vertical Axis – distance between plumb line dropped from anterior tubercle of C1 and posterior superior corner of C7; Horizontal white dotted line: C2-C7 Sagittal Vertical Axis—distance between plumb line dropped from centroid of C2 and posterior superior corner of C7; White dashed line: Center of Gravity-C7 Sagittal Vertical Axis—distance between plumb line dropped from anterior margin of external auditory meatus and posterior superior corner of C7.


Twenty-three patients who underwent C1 lateral mass screw (LMS)-C2 translaminar screw (TLS) and 29 who underwent C1 LMS-C2 pedicle screw(PS) fixation with ≥ 2 years of follow-up were retrospectively analyzed. Three-planar (sagittal, coronal, and axial) radiographic parameters were measured. Patient-reported outcomes (PROs) including the Neck Disability Index (NDI), Japanese Orthopaedic Association (JOA) score and the Short Form 36 Physical Component Summary (SF-36 PCS) were documented. Factors potentially associated with PROs were identified.

The radiographic parameters significantly changed postoperatively except the C1-2 midlines’ intersection angle in the TLS group (p = 0.073) and posterior atlanto-dens interval in both groups (p = 0.283, p = 0.271, respectively). The difference in bilateral odontoid lateral mass interspaces at last follow-up was better corrected in the TLS group than in the PS group (p = 0.010). Postoperative PROs had significantly improved in both groups (all p < 0.05). Thereinto, NDI at last follow-up was significantly lower in the TLS group compared with PS group (p = 0.013). In addition, blood loss and operative time were obviously lesser in TLS group compared with PS group (p = 0.010, p = 0.004, respectively). Multivariable regression analysis revealed that a change in C1-C2 sagittal Cobb angle was independently correlated to PROs improvement (NDI: β = -0.435, p = 0.003; JOA score: β = 0.111, p = 0.033; SF-36 PCS: β = 1.013, p = 0.024, respectively), also age ≤ 40 years was independently associated with NDI (β = 5.40, p = 0.002).

Three-planar atlantoaxial instability (AAI) should be reconstructed by C1 LMS-C2 PS fixation, while sagittal or coronal AAI could be corrected by C1 LMS-C2 TLS fixation. PROs may improve after atlantoaxial reconstruction in patients with chronic AAI. The C1-2 Cobb angle is an independent predictor of PROs after correcting chronic AAI, as is age ≤ 40 years for postoperative NDI 1).

1)

Pan Z, Xi Y, Huang W, Kim KN, Yi S, Shin DA, Huang K, Chen Y, Huang Z, He D, Ha Y. Independent Correlation of the C1-2 Cobb Angle With Patient-Reported Outcomes After Correcting Chronic Atlantoaxial Instability. Neurospine. 2019 Jun;16(2):267-276. doi: 10.14245/ns.1836268.134. Epub 2019 Jun 30. PubMed PMID: 31261466.

Tumor Embolization

Tumor Embolization

Indications

Tumor embolization is a procedure that can be performed prior to a planned surgical resection. Embolization shuts down the blood supply to a tumor reducing blood loss during surgical resection. A secondary benefit from embolization can be that tumor margins are more easily identified and a tumor can be removed more completely and with less effort. Tumors of the spine, head, and neck that can be embolized have relatively large blood vessels supplying the tumor.

● meningiomas:see Preoperative embolization of intracranial meningioma.

● hemangiopericytomas

● juvenile nasopharyngeal angiofibromas

● paraganglioma’s (carotid body tumor, glomus vagale, glomus jugulare),

● aneurysmal bone cyst

● hemangioblastomas

● vascular metastases from renal cell, thyroid, and chorio cancers.

Technique

A sheath is placed in the femoral artery and a guide catheter is positioned as close as possible to the vessels of interest e.g., in case of a meningioma the guide catheter tip is positioned in the proximal ECA. Angiography and roadmapping are performed through the guide catheter. Using fluoroscopy and road mapping, a microcatheter is advanced over wire into the branches supplying the tumor. Angiography is performed through the microcatheter to ascertain the branch supplies the tumor and no concerning collaterals with intracranial circulation exist. A blank road map is obtained and embolization commenced. PVA particles or Onyx may be used for embolization. In case of Onyx, a DMSO compatible catheter must be used. PVA may be cheaper and quicker to use for tumor embolization. However, the devascularization is not durable and the occluded ves- sels may recanalize; therefore, with PVA the surgery should be performed within a few days of the embolization.


If a tumor has a prominent blood supply then flow can be shut down to the tumor using 3 types of agents. All agents essentially perform the same task, i.e. reducing blood flow; however, they have slightly different properties and are used for different benefits.

NBCA or Onyx™ are polymer agents that consolidate over time and have similar properties to conventional superglues that are pushed through a catheter flowing forward from the catheter tip into vessels just short of the tumor itself. When forward flow stops they form a dense plug stopping blood supply to the tumor.

Microspheres or microbeads are tiny polyvinyl alcohol spheres or particles suspended in a sterile solution that are pushed through a catheter flowing forward from the catheter tip into vessels just short of the tumor itself. As they flow forward the vessel narrows and the particles lodge within the vessel forming a dam. As more particles lodge again a dense plug forms and blood flow stops.

Microcoils are tiny coils, similar to a “miniature slinky,” made from platinum or platinum like alloys that are pushed through a catheter with a special pusher rod. The coil deploys at the tip of the catheter and initially forms a mesh within the vessel being treated. More coils can then be deployed into the mesh. As coils are deployed the mesh structure reduces blood flow and when enough mesh is present, blood flow stops.

Timing

Embolization before surgical resection of tumors has been demonstrated to reduce intraoperative blood loss, but the optimal time that should elapse between embolization and tumor resection has not been established. We evaluated whether immediate surgical resection (< or =24 h) after embolization or delayed surgical resection (>24 h) was more effective in minimizing intraoperative blood loss.

Complications

Embolization for feeders other than ECA and use of liquid materials could increase the complication rate in intracranial tumor embolization 1).

References

1)

Hishikawa T, Sugiu K, Murai S, Takahashi Y, Kidani N, Nishihiro S, Hiramatsu M, Date I, Satow T, Iihara K, Sakai N; JR-NET2 and JR-NET3 study groups. A comparison of the prevalence and risk factors of complications in intracranial tumor embolization between the Japanese Registry of NeuroEndovascular Therapy 2 (JR-NET2) and JR-NET3. Acta Neurochir (Wien). 2019 Jun 7. doi: 10.1007/s00701-019-03970-w. [Epub ahead of print] PubMed PMID: 31172282.

Squash cytology

Squash cytology

Squash cytology is of significant importance in intraoperative consultation of central nervous system (CNS) pathology. There are several studies on squash cytology of CNS lesions, and only a few of them deal with spinal lesions alone.

(1) To evaluate intraoperative squash cytology of spinal lesions. (2) To correlate cytological diagnosis with histopathological diagnosis and assess the diagnostic accuracy. (3) To study Ki67 expression on squash smears and determine whether it can assist in grading spinal tumours on cytology.

A prospective study was conducted on 68 patients with clinico-radiologically diagnosed lesions of the spine. Intraoperative squash smears were stained with Hematoxylin and eosin stain, Papanicolaou (Pap) stain, and May-Grünwald-Giemsa (MGG) stain. Subsequently, histological diagnosis was made. Ki67 immunostaining was performed on squash smears and histology sections.

The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of squash cytology in spinal lesions were 84.6, 100, 100, 23.1, and 80.88%, respectively. On immunocytochemistry, the mean Ki67 labelling indices for grade I, II, and III tumours were 0, 0.33 and 9%, respectively.

Squash smear cytology is a rapid intraoperative technique for diagnosing spinal lesions, with high specificity and high positive predictive value. It is more effective in diagnosing neoplasms than non-neoplastic lesions. Ki67 immunostaining can be done on cytology smears to effectively differentiate between WHO grade I and grade II spinal tumor1).


One hundred and fifty cases of CNS lesions in pediatric patients were studied over a period of 2 years. Intraoperative squash smears were prepared, stained with hematoxylin and eosin, and examined. Remaining sample was subjected to histopathological examination.

Medulloblastoma (24.0%) was the most frequently encountered tumor followed by pilocyctic astrocytoma (21.33%) and ependymoma (13.33%). Diagnostic accuracy of squash smear technique was 94.67% when compared with histological diagnosis.

Smear cytology is a fairly accurate tool for intraoperative CNS consultations 2).


Fifty prospectively registered patients with clinical diagnosis of CNS tumors were enrolled in the study. All the patients were subjected to magnetic resonance imaging (MRI). Intraoperative CSC was performed and smears were stained with Leishman and rapid Hematoxylin and Eosin (H and E) stain. The diagnosis of CSC was compared with MRI diagnosis and histopathological diagnosis. The CNS tumors were categorized based on clinical and therapeutic implications. Diagnostic accuracy, sensitivity, specificity, and positive and negative predictive value of MRI and CSC were calculated by using appropriate formulae.

The age range of the CNS tumors included in the study was 2 to 68 years. There was a slight female preponderance. Sensitivity, specificity, positive predictive value, and negative predictive value of preoperative MRI were 90.47%, 82.76%, 79.17%, and 92.31% respectively. These values of utility parameters for CSC were 100% for each of the clinical and therapeutic implications. It helped neurosurgeons in optimizing surgical procedure in 12 cases of meningioma. It influenced surgical management in 1 case of infratentorial pilocytic astrocytoma, and helped in the diagnosis and management of 9 unexpected tumors missed on MRI 3).


A prospective study of 114 patients with CNS tumors was conducted over a period of 18 months (September 2004 to February 2006). The cytological preparations were stained by the quick Papanicolaou method. The squash interpretation and FS diagnosis were later compared with the paraffin section diagnosis.

Of the 114 patients, cytological diagnosis was offered in 96 cases. Eighteen nonneoplastic or noncontributory cases were excluded. Using hematoxylin and eosin-stained histopathology sections as the gold standard, the diagnostic accuracy of cytology was 88.5% (85/96) and the accuracy on FS diagnosis was 90.6% (87/96). Among these cases, gliomas formed the largest category of tumors (55.2%). The cytological accuracy in this group was 84.9% (45/53) and the comparative FS figure was 86.8% (46/53). In cases where the smear and the FS diagnosis did not match, the latter opinion was offered.

Squash preparation is a reliable, rapid and easy method and can be used as a complement to FS in the intraoperative diagnosis of CNS tumors 4).

References

1)

Chakrabarty D, Chaudhuri S, Maity P, Chatterjee U, Ghosh S. Utility of Squash Cytology in Spinal Lesions with Special Reference to Ki67 Immunostain. Acta Cytol. 2019 Jun 24:1-7. doi: 10.1159/000500681. [Epub ahead of print] PubMed PMID: 31234167.
2)

Jindal A, Kaur K, Mathur K, Kumari V, Diwan H. Intraoperative Squash Smear Cytology in CNS Lesions: A Study of 150 Pediatric Cases. J Cytol. 2017 Oct-Dec;34(4):217-220. doi: 10.4103/JOC.JOC_196_15. PubMed PMID: 29118478; PubMed Central PMCID: PMC5655660.
3)

Patil SS, Kudrimoti JK, Agarwal RD, Jadhav MV, Chuge A. Utility of squash smear cytology in intraoperative diagnosis of central nervous system tumors. J Cytol. 2016 Oct-Dec;33(4):205-209. doi: 10.4103/0970-9371.190442. PubMed PMID: 28028335; PubMed Central PMCID: PMC5156983.
4)

Mitra S, Kumar M, Sharma V, Mukhopadhyay D. Squash preparation: A reliable diagnostic tool in the intraoperative diagnosis of central nervous system tumors. J Cytol. 2010 Jul;27(3):81-5. doi: 10.4103/0970-9371.71870. PubMed PMID: 21187881; PubMed Central PMCID: PMC2983079.
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