Intracranial metastases surgery

Intracranial metastases surgery

see Intracranial metastases surgery indications.

Intracranial Metastases Surgical Technique.


Automated classification of brain metastases and healthy brain tissue is feasible using optical coherence tomography imaging, extracted texture features, and machine learning with principal component analysis (PCA) and support-vector machines (SVM). The established approach can prospectively provide the surgeon with additional information about the tissue, thus optimizing the extent of tumor resection and minimizing the risk of local recurrences 1).

Wolpert et al. defined risk profiles for the development of BM-related epilepsy and derived a score which might help to estimate the risk of post-operative seizures and identify individuals at risk who might benefit from primary prophylactic antiepileptic drug therapy 2).


1)

Möller J, Bartsch A, Lenz M, Tischoff I, Krug R, Welp H, Hofmann MR, Schmieder K, Miller D. Applying machine learning to optical coherence tomography images for automated tissue classification in brain metastases. Int J Comput Assist Radiol Surg. 2021 May 30. doi: 10.1007/s11548-021-02412-2. Epub ahead of print. PMID: 34053010.
2)

Wolpert F, Lareida A, Terziev R, Grossenbacher B, Neidert MC, Roth P, Poryazova R, Imbach L, Le Rhun E, Weller M. Risk factors for the development of epilepsy in patients with brain metastasis. Neuro Oncol. 2019 Sep 10. pii: noz172. doi: 10.1093/neuonc/noz172. [Epub ahead of print] PubMed PMID: 31498867.

Posterior parietal cortex

Posterior parietal cortex

The posterior parietal cortex (the portion of parietal neocortex posterior to the primary somatosensory cortex) plays an important role in planned movements, spatial reasoning, and attention.

Damage to the posterior parietal cortex can produce a variety of sensorimotor deficits, including deficits in the perception and memory of spatial relationships, inaccurate reaching and grasping, in the control of eye movement, and inattention. The two most striking consequences of PPC damage are apraxia and hemispatial neglect.


Pereira et al. from Geneva showed that perceptual consciousness and monitoring involve evidence accumulation. They performed single-unit recording in a participant with a microelectrode in the posterior parietal cortex, while they detected vibrotactile stimuli around the detection threshold and provided confidence estimates. They find that detected stimuli elicited neuronal responses resembling evidence accumulation during decision-making, irrespective of motor confounds or task demands. They generalized these findings in healthy volunteers using electroencephalography. Behavioral and neural responses are reproduced with a computational model considering a stimulus as detected if accumulated evidence reaches a bound, and confidence as the distance between maximal evidence and that bound. They concluded that gradual changes in neuronal dynamics during evidence accumulation relates to perceptual consciousness and perceptual monitoring in humans 1)


Spatial remapping, the process of updating information across eye movements, is an important mechanism for trans-saccadic perception. The right posterior parietal cortex (PPC) is a region that has been associated most strongly with spatial remapping. The aim of a project of Ten Brink et al. was to investigate the effect of damage to the right PPC on direction specific transsaccadic memory. They compared trans-saccadic memory performance for central items that had to be remembered while making a left- versus rightward eye movement, or for items that were remapped within the left versus right visual field.

They included 9 stroke patients with unilateral right PPC lesions and 31 healthy control subjects. Participants memorized the location of a briefly presented item, had to make one saccade (either towards the left or right, or upward or downward), and subsequently had to decide in what direction the probe had shifted. We used a staircase to adjust task difficulty (i.e., the distance between the memory item and probe). Bayesian repeated measures ANOVAs were used to compare left versus right eye movements and items in the left versus right visual field.

In both conditions, patients with right PPC damage showed worse trans-saccadic memory performance compared to healthy control subjects (for the condition with left- and rightward gaze shifts, BF10 = 3.79; and when items were presented left or right, BF10 = 6.77), regardless of the direction of the gaze or the initial location of the memory item. At the individual level, none of the patients showed a direction specific deficit after leftward versus rightward saccades, whereas two patients showed worse performance for items in the left versus right visual field.

Damage in the right PPC did not lead to gaze direction specific impairments in trans-saccadic memory, but instead caused more general spatial memory impairments 2).


1)

Pereira M, Megevand P, Tan MX, Chang W, Wang S, Rezai A, Seeck M, Corniola M, Momjian S, Bernasconi F, Blanke O, Faivre N. Evidence accumulation relates to perceptual consciousness and monitoring. Nat Commun. 2021 May 31;12(1):3261. doi: 10.1038/s41467-021-23540-y. PMID: 34059682.
2)

Ten Brink AF, Fabius JH, Weaver NA, Nijboer TCW, Van der Stigchel S. Trans-saccadic memory after right parietal brain damage. Cortex. 2019 Jun 28;120:284-297. doi: 10.1016/j.cortex.2019.06.006. [Epub ahead of print] PubMed PMID: 31376588.

Type III odontoid fracture

Type III odontoid fracture

A type III odontoid fracture is a fracture through the body of the C2 vertebrae and may involve a variable portion of the C1 and C2 facets.

Type III fractures account for 39% of all odontoid fractures 1).

Type III odontoid fractures occur secondary to hyperextension or hyperflexion of the cervical spine in a similar manner to type II odontoid fractures. The difference is where the fracture line occurs.

In clinical practice, the Type III fracture encompasses a heterogeneous collection of morphologically different fractures of varying etiologies and patient demographics. At trauma centers, a complex, high-energy subtype exists that radiographically fits the definition of Type III odontoid fracture but of unknown clinical context.

Fractures with >50% comminution of the lateral mass or secondary fracture lines extending into the vertebral body or pars interarticularis were classified as complex by Niemeier et al. Biomechanically, complex fractures exhibit the same deforming forces as all odontoid fractures with additional instability in the rotatory or coronal plane 2).

Type III odontoid fracture treatment.

In general, the Type III fracture is believed to have high healing potential due to the large fracture surface area through cancellous bone 3).

Imaging pearl. A type III odontoid fracture may be misinterpreted as odontoid fracture type II on sagittal CT because the fracture may appear to lie above the vertebral body (VB). Always check the coronal view, which more readily demonstrates the relationship of the fracture to the VB.

Acute Type III odontoid fractures were identified at a single institution from 2008 to 2015. Fractures were categorized as high- or low-energy fracture with high-energy fractures defined as those with lateral mass comminution (>50%) or secondary fracture lines into the pars interarticularis or vertebral body. Patients were treated in either a hard collar orthosis or halo vest and were followed for fracture union and stability.

One hundred and twenty-five Type III odontoid fractures were identified with 51% classified as complex fractures. Thirty-three patients met the inclusion and exclusion criteria including 15 patients treated in a halo vest and 18 in a hard collar orthosis. Mean follow-up was 32 (±44) weeks. Seven patients demonstrated progressive displacement of either 2 mm of translation or 5° of angulation and underwent delayed surgical stabilization. Two additional patients required delayed surgery for nonunion and myelopathy. Initial fracture displacement and angulation were not correlative with final outcome. No statistical advantage of halo vest versus hard collar orthosis was observed.

Complex Type III odontoid fractures are distinctly different from low-energy injuries. In the current study, 21% of patients were unsuccessfully treated nonoperatively with external immobilization and required surgery. For complex Type III fractures, they recommended initial conservative treatment, while maintaining close monitoring throughout patient recovery and fracture union 4).

A young woman who suffered a severe polytrauma secondary to a motor vehicle collision was diagnosed with a sagittal plane atlantoaxial joint dislocation associated with a type III odontoid fracture, despite adequate initial polytrauma management, the neurological damage was too critical, ultimately the decease of the patient.

The atlantoaxial joint dislocation is a rare condition of the upper cervical spine and is usually secondary to a high-energy traumatism. The disruption of the atlantoaxial ligaments originates the considered most unstable cervical spine lesion and with the highest mortality. Attributable to the kinetic the bone fracture of the Atlas and Axis are commonly related, especially the odontoid process. Early immobilization followed by surgical decompression and stabilization is primordial. Typically, these injuries have an ominous prognosis, that is aggravated if added a polytrauma affecting adjacent neurological structures and other vital organs 5).


1)

Greene KA, Dickman CA, Marciano FF, Drabier JB, Hadley MN, Sonntag VK. Acute axis fractures. Analysis of management and outcome in 340 consecutive cases. Spine (Phila Pa 1976). 1997 Aug 15;22(16):1843-52. PubMed PMID: 9280020.
2) , 4)

Niemeier TE, Dyas AR, Manoharan SR, Theiss SM. Type III odontoid fractures: A subgroup analysis of complex, high-energy fractures treated with external immobilization. J Craniovertebr Junction Spine. 2018 Jan-Mar;9(1):63-67. doi: 10.4103/jcvjs.JCVJS_152_17. PubMed PMID: 29755239; PubMed Central PMCID: PMC5934967.
3)

Hanssen AD, Cabanela ME. Fractures of the dens in adult patients. J Trauma. 1987 Aug;27(8):928-34. doi: 10.1097/00005373-198708000-00013. PMID: 3612871.
5)

Sánchez-Ortega JF, Vázquez A, Ruiz-Ginés JA, Matovelle PJ, Calatayud JB. Longitudinal atlantoaxial dislocation associated with type III odontoid fracture due to high-energy trauma. Case report and literature review. Spinal Cord Ser Cases. 2021 May 25;7(1):43. doi: 10.1038/s41394-021-00407-4. PMID: 34035212.
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