**Abstract**

A mathematical model for convective heat and mass transfer of two immiscible fluids in a vertical channel of variable width with thermo-diffusion, diffusionthermal effects is presented. The governing boundary layer equations generated for momentum, angular momentum, energy and species concentration are solved with appropriate boundary conditions using Galeriken finite element method. The effects of the pertinent parameters are studied in detail. Furthermore, the rate of heat transfer, mass transfer and shear stress near both walls is analyzed.

**Keywords:** vertical channel, immiscible fluids, finite element method, heat and mass transfer


*6.4. The Final Sai*

The final *sai* started after a lunch break with 'Offering Three Cups', which followed the same procedure and pattern as performed in the initial *sai*, with group skits presented in between. Next came a *nuo*-exorcism ritual called 'Rinsing Off Plagues' (*chongwen* 沖 瘟). This ritual was fairly simple in form but quite engaging. In the beginning, a miniature 'plague boat' (*wenchuan* 瘟 船) made of paper was brought in and placed on firewood in front of the Incense Pavilion. Then, the Chief Master of Ceremonials recited 'the Writ of Exorcising Evil Spirits' (*Quxie wen* 驅 邪 文). While he was reciting the text, a ritual attendant set fire to the paper boat under the watchful eye of the Chief Master of Ceremonials. After that, a boy and a girl, about five or six years old, were brought in by their respective fathers. With their child held firmly on the chest, they jumped over the flaming boat in the presence of a large crowd of spectators, who reacted with a hearty round of applause. The ritual of 'Rinsing Off Plagues' is an ancient form of *nuo* exorcism performed during the temple festival to cleanse the community of evil spirits and epidemic diseases, and this is also the case with *Dancing Jianzhai* and *A Monkey Extracted from Its Shell*, both of which are key pieces in the repertoire of local Nuo theatre (*nuoxi* 儺 戲) (Du 2016).

The final *sai* then proceeded to 'Beating the Drum of the Supreme Peace' (*da taipinggu* 打太 平 鼓), which was presented in front of the Incense Pavilion by a troupe of drummers from the Assembly of Eight Sounds to pray for peace and prosperity. Following the drum music was 'Offering Sacrifices to the Wind' (*jifeng* 祭 風), which was performed in each of the four corners of the village, starting clockwise from the eastern corner. The ritual involved erecting an altar (Figure 56), offering incense, kowtowing and reciting sacrificial texts (*jiwen* 祭 文) (Figure 57).

Among the various ritual, musical and theatrical performances for the final *sai*, the most important is 'Seeing Off the Deities According to Their Wishes' (*Songshen dacai* 送 神 打 彩).51 Similar to 'Inviting the Deities' and 'Welcoming the Deities', 'Seeing Off the Deities' is a grand procession, in which the gods and goddesses are carried in their sedan chairs, divine carriages or spirit tablets back to their own temples or shrines.  He then rose to his feet to chant the 'Writ of Seeing Off the Deities' (*Songshen wen* 送 神 文), which contained a long list of the invited deities and of the divine blessings the local community had received from them (Figure 58). Following the chanting of the ritual text was 'Offering Three Cups'. A village elder was invited to say prayers of grateful thanks to the goddess and her invited deities (Figure 59).

**Figure 56.** An Altar Is Set Up for the Ritual of Offering Sacrifices to Wind.

Wang Jinzhi then led all Entertainers from the Assembly of Eight Sounds to perform a music and dance to honour the gods and goddess, and after that, they walked up one by one to make a deep obeisance in thanksgiving for their divine grace. With the (sedan chairs, divine carriages and spirit tablets of) invited deities being carried back to their home shrines and temples, the final *sai* came to an end.

**Figure 57.** Offering Sacrifices to Wind.

**Figure 58.** The Chief Master of Ceremonials Chants the 'Writ of Seeing Off Deities'.

**Figure 59.** Village Elder Kneels Down to Kowtow.


**2.2. Cell culture models**

*StemRegenin 1* (*SR-1*) binds and inhibits the AhR, which mediates toxicity of environmental pollutants, by binding to specific DNA enhancer sequences. This receptor can be activated by endogenous or exogenous ligands and contributes to several physiological processes, among which cell migration, apoptosis, and cell growth [74–77]. Importantly, AhR-deficient mice have increased numbers of BM HSCs [78]. The AhR functions in complex with the AhR Nuclear Translocator to induce differentiation by regulating genes directly such as *c-MYC* and *C/EBP*. During hematopoietic differentiation, its targets also include *PU.1, β-CATENIN, CXCR4,* and *STAT5* [79]. Currently, the antagonist of AhR (SR-1) is used in clinical trials to

needed per transplant from 5 to 1 [80]. Importantly, SR-1 also enhances *in vitro* proplatelet formation [81]. To achieve proper Plts production, MKs have to produce an extensive membrane system; the demarcation membrane system. This requirs extensive lipid biosynthesis which can be inhibited by AhR [82]. Thus, blocking the inhibition of AhR with SR-1 may increase the

EPO is sufficient for steady-state erythropoiesis, when proliferative signals are mediated through the EPOR-associated RON receptor and EPO-induced differentiation is dependent on STAT5 [83, 84]. Increased erythropoiesis during development and upon blood loss requires the cooperative action of the EPOR and KIT [85]. Activation of KIT prevents differentiation and propagates the long-term proliferation of erythroid progenitors through inhibition of *FOXO3a* and activation of mRNA translation via the PI3K/mTOR pathway [86, 87]. Activation of the GR is required for stress erythropoiesis and to inhibit *in vitro* differentiation. Interestingly, glucocorticoids activate largely the same growth inhibitory genes in EBLs and in immune cells, but growth inhibition is counteracted by EPOR/KIT activation [88]. Even in the presence of serum, glucocorticoids promote selective proliferation of erythroid progenitors by both supporting erythroid proliferation and inhibiting proliferation of other myeloid and lymphoid cells [57]. Erythropoiesis is also regulated by the availability of iron, which is imported into the cell as holotransferrin via the transferrin receptor (TfR; CD71), and by selenium through selenoproteins [89, 90]. *In vivo*, erythropoiesis is dependent on the formation of erythropoietic islands that form around a central macrophage [91, 92]. Whereas CD169 macrophages are essential for erythropoiesis *in vivo*, high level of enucleation can be achieved *in vitro* in the absence of macrophages (van den Akker and von Lindern, manuscript in preparation) [93]. The complete understanding of which macrophage signals control enucleation *in vivo* may further

proplatelet formation, through increasing the lipid membrane biosynthesis.

optimize the *in vitro* production of erythrocytes for transfusion purposes.

TPO is the main regulator of megakaryopoiesis, and multiple other factors can work synergistic with it. IL-6 can, in conjunction with TPO, increase hepatic TPO synthesis [94]. This effect is through the shared usage of gp130 and amplification of the same downstream JAK pathways [95]. The direct admission of IL-6, besides its effect on TPO, results in increased polyploidization and subsequently leads to an enhanced Plts production in patients [96]. IL-11 is not constitutively expressed but was shown to be induced in thrombocytopenia patients undergoing

cells prior to transplantation, thereby reducing the number of CB units

expand CB-CD34<sup>+</sup>

250 Cell Culture

*2.1.4. Erythroid-specific regulation*

*2.1.5. MK-specific regulation*


**Principles of Haemodiafiltration: Rationale for Improved Patients' Survival**

Goran Imamović, Bernard Canaud, Nusret Mehmedović and Cäcilia Scholz

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/63067

#### **Abstract**

Haemodiafiltration (HDF) is a renal replacement modality that combines diffusion and enhanced convection in order to remove small- and middle-molecular-weight com‐ pounds, respectively. They are removed along solvent drag effect of ultrafiltration through increased transmembrane pressure (TMP), whereas the replacement solution is infused intravenously at equal amount minus the desired fluid volume removal for achieving dry weight. Limiting factors for high-volume on-line haemodiafiltration (HV oHDF) are blood flow and viscosity (haematocrit, protocrit), filter performance and technical features of HDF monitor. Most recent advanced technology of dynamic analysis of pressure pulses along the blood flow pathway in the dialyser has enabled optimal ultrafiltration flow performances. HV oHDF offers today the best compromise of cardioprotective option by reducing cardiovascular risk factors in end-stage kidney disease patients. Recent randomised controlled trials (RCTs), individual participant data meta-analyses and a number of observational studies have shown the evidence of survival advantage of HDF over conventional haemodialysis (HD). The convective volume has become the key quantifier for HV oHDF as the measure of dialysis dose. Its cut-off values for better survival have been recognised, but the research is still needed in the years to come to set the required optimal volumes tailored to individual patients' needs.

**Keywords:** haemodialysis, haemodiafiltration, convection, ultrafiltration, mortality

### **1. Introduction**

The uremic syndrome is characterised by an accumulation of uremic toxins due to inadequate kidney function. There have been more than 90 compounds considered to be uremic toxins listed

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

by the European Uremic Toxin Work Group. Sixty-eight have a molecular weight less than 500Da, 10have amolecularweightbetween500 and12,000Da and12 exceed12,000Da.Twentyfive solutes (28%) are protein bound [1]. These figures are further increasing with the adop‐ tion of new knowledge and technology of uremic toxins detection.

The clearance of solutes during conventional haemodialysis (HD) depends on their size and the concentration gradient across the dialysis membrane. Solutes weighing less than 500 Da are considered low-molecular-weight solutes and they are removed by passive diffusion down a favourable concentration gradient. Urea is considered a marker of such toxins. Its clearance, as measured by Kt/Vurea, correlates with patient morbidity [2] showing the evidence that such toxins contribute to the uremic syndrome.

However, despite improvements in technology and patient care, the mortality rate of patients on maintenance dialysis remains high, at approximately 15–20% per year [3]. As specified in the United States Renal Data System report, the expected remaining life span after the initiation of renal replacement therapy was eight years for dialysis patients aged 40–44 and 4.5 years for those 60–64 years of age. In general population the ranges of the expected remaining life span at specified ages are 30–40 years and 17–22 years, respectively. The values in older dialysis patients are only slightly better than those in patients with lung cancer [4]. Therefore, there is an obvious need to change the practices and to attempt to approach the problem differently.


5. High-pressure carbon dioxide applications

The most cited drawback of using supercritical carbon dioxide as solvent is the high investment cost for equipment acquisition and operation. However, the extraction with supercritical carbon dioxide presents a lower extraction time because of its diffusivity and low surface tension, greater selectivity in the compounds of interest and little or no consumption of organic solvents [43–46].

As given above, it is observed that the process of extraction of essential oils using supercritical CO2 is ecologically a cleaner method than the conventional ones, and it has been seen as one of

Carbon Dioxide Use in High-Pressure Extraction Processes

http://dx.doi.org/10.5772/intechopen.71151

227

Phytosterols (plant sterols) are non-volatile triterpenes. The great majority of these compounds are formed by carbon with one or two carbon-carbon double bonds [62]. And the most common phytosterols found in plants are β-sitosterol, campesterol, and stigmasterol [63]. These compounds have various biological activities such as lowering the total serum or plasma cholesterol levels and the low-density lipoprotein cholesterol levels. In addition, they have

For the extraction of these phytosterols, the supercritical CO2 has been shown to be an efficient technique for extraction of fixed oils from vegetable matrices. Studies report that this solvent may be superior to obtain oils in relation to the conventional extraction, exhibiting a recovery rate of phytosterols of 836.5 mg/100 g versus 30.5/100 g using a Soxhlet-type extraction apparatus [66]. A very important parameter for the extraction of phytosterols with supercritical CO2 is the increase of the pressure, because it favors the solvation power and consequently the solubilization of these compounds, with a recovery rate of up to 7262.80 mg.kg1 [67]. Table 6 presents some articles published in the literature on the extraction of phytosterols

Carotenoids are tetraterpenes present in plants that have several applications in food [72], cosmetic [73], and pharmaceutical [74] areas. Some of the benefits provided by these pigments are: antioxidant activity and strengthening of the immune system against degenerative diseases such as cancer, cardiovascular diseases, muscle degeneration, inflammation, hyperten-

Because of their hydrophobic characteristics, carotenoids are usually extracted using organic solvents such as hexane and petroleum ether. Carotenoids with hydrophilic characteristics can be obtained with more polar solvents such as acetone, ethanol, and ethyl acetate [77]. The

Plants Phytosterols References

Brassica napus β-sitosterol, campesterol and brassicasterol [69] Hippophae rhamnoides L. β-sitosterol [70]

stigmastatrienol, Δ7-stigmastenol, Δ7,25-stigmastadienol, and Δ7-avenasterol

cholesterol, Δ-5 avenasterol and stigmasterol, while lower levels of Δ-5,24 stigmastadienol, brassicasterol, clerosterol + Δ-5-23 stigmastadienol, Δ-7

[68]

[71]

Cucurbita pepo convar Desmosterol, campesterol, stigmasterol, β-sitosterol, spinasterol, Δ7,22,25-

Sesamum indicum L. β-sitosterol + sitostanol, cholesterol, campesterol + campestanol +24-methylene

avenasterol, eritrodiol and Δ-7 stigmasterol

antitumor activities inhibiting the development of colon cancer [64, 65].

the most viable alternatives.

5.2. Phytosterols extraction

using supercritical CO2.

5.3. Carotenoid extraction

sion, insulin resistance and obesity [75, 76].

Table 6. Phytosterols extracted using supercritical CO2

### 5.1. Essential oil extraction

Essential oils have been used to prevent or treat human diseases for several centuries. The extraction of the volatile compounds present in edible or medicinal aromatic plants is generally carried out by hydrodistillation; however, the authors report that some compounds may undergo hydrolysis during the extraction period [47]. Although there are other techniques for isolating essential oils, the use of CO2 as supercritical fluid has been considered a "chemically green" unconventional extraction technique that does not alter or degrade the substances present in oils because it uses relatively low temperatures in the extraction process.

Guan et al. [48] performed a comparison between conventional extraction methods and extraction with supercritical CO2 and observed that the extraction using supercritical CO2 as solvent was less effective with recovery rate of 57.36% for eugenol compared to steam distillation with 58.2%, but it was more effective when compared to hydrodistillation with recovery rate of 48.82% and Soxhlet extraction with 57.24%. However, when compared with the extraction of eugenol acetate, the extraction with supercritical CO2 presented higher yields in relation to the other extraction methods.

Extraction of chemically active volatile molecules with supercritical CO2 is very widespread [49–51]. This is due to the possible applications as agents that promote biological activities [52], such as antioxidant activity [53], anti-inflammatory activity [54], insecticidal activity [55], and phytotoxic activity [56]. In Table 5, some studies in the literature on the extraction of essential oils with supercritical CO2 can be observed.

Table 5. Published studies on extraction of essential oils using CO2 as supercritical fluid.

As given above, it is observed that the process of extraction of essential oils using supercritical CO2 is ecologically a cleaner method than the conventional ones, and it has been seen as one of the most viable alternatives.

### 5.2. Phytosterols extraction

5. High-pressure carbon dioxide applications

solvents [43–46].

5.1. Essential oil extraction

226 Carbon Dioxide Chemistry, Capture and Oil Recovery

other extraction methods.

oils with supercritical CO2 can be observed.

dibutyl phthalate

The most cited drawback of using supercritical carbon dioxide as solvent is the high investment cost for equipment acquisition and operation. However, the extraction with supercritical carbon dioxide presents a lower extraction time because of its diffusivity and low surface tension, greater selectivity in the compounds of interest and little or no consumption of organic

Essential oils have been used to prevent or treat human diseases for several centuries. The extraction of the volatile compounds present in edible or medicinal aromatic plants is generally carried out by hydrodistillation; however, the authors report that some compounds may undergo hydrolysis during the extraction period [47]. Although there are other techniques for isolating essential oils, the use of CO2 as supercritical fluid has been considered a "chemically green" unconventional extraction technique that does not alter or degrade the substances

Guan et al. [48] performed a comparison between conventional extraction methods and extraction with supercritical CO2 and observed that the extraction using supercritical CO2 as solvent was less effective with recovery rate of 57.36% for eugenol compared to steam distillation with 58.2%, but it was more effective when compared to hydrodistillation with recovery rate of 48.82% and Soxhlet extraction with 57.24%. However, when compared with the extraction of eugenol acetate, the extraction with supercritical CO2 presented higher yields in relation to the

Extraction of chemically active volatile molecules with supercritical CO2 is very widespread [49–51]. This is due to the possible applications as agents that promote biological activities [52], such as antioxidant activity [53], anti-inflammatory activity [54], insecticidal activity [55], and phytotoxic activity [56]. In Table 5, some studies in the literature on the extraction of essential

Aromatic plant Bioactive compounds References

[61]

Juniperus communis L. Germacrene D and 1-octadecene. [57] Satureja hortensis γ-Terpinene, thymol, and carvacrol [58] Myrtus communis L. Methyl eugenol, 1,8 cineole, and beta- caryophyllene [59] Leptocarpha rivularis α-thujone, β-caryophyllene, and caryophyllene oxide [60] Piper nigrum L. β-caryophyllene, limonene, sabinene, 3-carene, β-pinene, and α-pinene [53]

Camellia sinensis L. 9-Thiabicyclo[3.3.1]non-7-en-2-ol, tricosane, heneicosane, tetracosane, and

Table 5. Published studies on extraction of essential oils using CO2 as supercritical fluid.

present in oils because it uses relatively low temperatures in the extraction process.

Phytosterols (plant sterols) are non-volatile triterpenes. The great majority of these compounds are formed by carbon with one or two carbon-carbon double bonds [62]. And the most common phytosterols found in plants are β-sitosterol, campesterol, and stigmasterol [63]. These compounds have various biological activities such as lowering the total serum or plasma cholesterol levels and the low-density lipoprotein cholesterol levels. In addition, they have antitumor activities inhibiting the development of colon cancer [64, 65].

For the extraction of these phytosterols, the supercritical CO2 has been shown to be an efficient technique for extraction of fixed oils from vegetable matrices. Studies report that this solvent may be superior to obtain oils in relation to the conventional extraction, exhibiting a recovery rate of phytosterols of 836.5 mg/100 g versus 30.5/100 g using a Soxhlet-type extraction apparatus [66]. A very important parameter for the extraction of phytosterols with supercritical CO2 is the increase of the pressure, because it favors the solvation power and consequently the solubilization of these compounds, with a recovery rate of up to 7262.80 mg.kg1 [67]. Table 6 presents some articles published in the literature on the extraction of phytosterols using supercritical CO2.

### 5.3. Carotenoid extraction

Carotenoids are tetraterpenes present in plants that have several applications in food [72], cosmetic [73], and pharmaceutical [74] areas. Some of the benefits provided by these pigments are: antioxidant activity and strengthening of the immune system against degenerative diseases such as cancer, cardiovascular diseases, muscle degeneration, inflammation, hypertension, insulin resistance and obesity [75, 76].

Because of their hydrophobic characteristics, carotenoids are usually extracted using organic solvents such as hexane and petroleum ether. Carotenoids with hydrophilic characteristics can be obtained with more polar solvents such as acetone, ethanol, and ethyl acetate [77]. The

Table 6. Phytosterols extracted using supercritical CO2

techniques used to extract this compound may be maceration, Soxhlet, microwave-assisted extraction [78, 79], ultrasound-assisted extraction [80], pressurized liquid extraction [81, 82], and supercritical fluid technology using low temperature. The process is performed in a short time in relation to conventional processes and does not use toxic solvents to collect the compound of interest [83]. In Table 7, some published works that used supercritical CO2 to obtain carotenoids are shown.

### 5.4. Fatty acids extraction

Fatty acids (FA) belong to the lipid class and differ according to the size of the C chain (2–80), the presence or absence of double bonds (saturated or unsaturated) or their radical function as the groups hydroxyl, epoxy, and halogen atoms [89]. Ingestion of FA is essential to have an adequate energy balance in the human organism in addition to reducing the risk of some diseases such as diabetes [90], hypertension [91], coronary diseases [92], and inflammation [93].

Some of its applications are in food, nutraceutical, and cosmetic industries, and in the production of lubricants, biodiesel, and glycerol [94–96]. Some of the extraction methods that can be used to obtain FA are mechanical extraction [97], extraction by supercritical fluids and organic solvent [98], microwave-assisted extraction [99], and supercritical CO2 extraction [98]. Table 8 shows some studies that used supercritical CO2 to obtain the main classes of the FA group.

non-polar molecule and does not have "power" to solubilizate polar substances as is the case of the phenolic compounds (phenolic acids and flavonoids) [105, 106]. As previously mentioned, parameters of processes, such as temperature and pressure, can influence the extraction of bioactive compounds. Besides these two parameters, anthocyanins are also important for the extraction of phenolic compounds. Solvent flow rate, percentage of co-solvent, co-solvent type (ethanol or water), and extraction time are parameters that directly implicate the yield of

3-O-galactoside, delphinidin 3-O-arabinoside, cyanidin 3-O-glucoside, petunidin 3-O-galactoside, cyanidin 3-O-arabinoside, petunidin 3-O-glucoside, peonidin 3-O-galactoside, petunidin 3-O-arabinoside, peonidin 3-O-glucoside, malvidin 3-O-galactoside, peonidin

3-O-arabinoside, malvidin 3-O-glucoside, malvidin 3-O-arabinoside and

Raw material Compounds References

[113]

229

Carbon Dioxide Use in High-Pressure Extraction Processes

http://dx.doi.org/10.5772/intechopen.71151

[114]

Myrciaria cauliflora Anthocyanin [8] Elderberry (Sambucus nigra) Anthocyanins [110] Vitis vinifera var. Malvasia nera Anthocyanins [111] Arrabidaea chica Anthocyanins and luteolin [112] Scutellaria lateriflora L. Baicalin, dihydrobaicalin, lateriflorin, ikonnikoside I, scutellarin, oroxylin A 7-O-glucuronide, oroxylin A, baicalein, wogonin

Vaccinium myrtillus L. Delphinidin 3-O-galactoside, delphinidin 3-O-glucoside, cyanidin

malvidin 3-O-xyloside

Table 9. Phenolic compounds extracted with supercritical CO2 modified with ethanol/water.

Further examples of extraction of phenolic compounds using supercritical CO2 modified with co-solvents can be analyzed in the studies [106, 108, 109]. They extracted various flavonoids like quercetin, catechin, epicatechin from cranberry, blueberry, and raspberry. Table 9 presents some studies in which supercritical CO2 modified with ethanol/water were used to extract

Carbon dioxide can be safely applied in high-pressure extraction processes due to its numerous advantageous characteristics. It is neither toxic nor inflammable, being able to act as solvent, cosolvent, or anti-solvent, which allows it to be used in natural products and foodstuff processing that require treatments intending to preserve their nutritional and sensory properties. Since it is a non-polar substance, it is suitable for extraction of non-polar bioactive compounds when used in pure form. When associated with a polar co-solvent, it can be used for extraction of polar compounds such as phenolic compounds and anthocyanins. Therefore, these characteristics make carbon dioxide the most important fluid used in high-pressure processes for extraction, separation, fractionation, micronization, and encapsulation, applied to obtain concentrated

extracts with bioactive compounds for food, pharmaceutical, and cosmetic applications.

these substances at the end of the extraction process [107].

chemically active phenolic compounds.

6. Conclusion


**2.1. Management and surgical indication**

The evaluation of clinical general and neurological conditions of patients with advanced cancer and spinal metastases is performed with the Karnowsky performance scale (KPS) and the American Spinal Injury Association (ASIA) scores. Total spine MRI and total body CT scan is mandatory in order to update the stadium of the disease and to planning the most correct treatment.

Approximately 90% of cancer patients with spinal metastases have bone and/or back pain, followed by radicular pain. Half of these patients have sensory and motor dysfunction, and more than half have bowel and bladder dysfunction. Five to 10% of cancer patients present with cord compression as their initial symptom; among these, 50% are non-ambulatory at diagnosis, and 15% are paraplegic [8].

The initial functional neurological score, evaluated with ASIA score, is the most important prognostic factor for the neurological recovery of patients undergoing surgery. Surgery, in the

majority of spinal metastasis cases, does not have a curative aim, but only palliative, to assure stability, pain control, and maintenance of neurologic integrity [3]. Surgery is also important to confirm the primary diagnosis, to debulk or remove the tumor mass for a more effective adjuvant therapy, and permit a patient's mobilization.

The main indications for surgery in case of spinal metastases are the progressive neurologic deficit before, during, or after chemo- and radiotherapy, the intractable pain unresponsive to conservative treatment, the need for histological diagnosis, the treatment of radio-resistant tumor histology (e.g., RCC, melanoma), and to restore the spinal stability.

Numerous grading systems has been proposed, like the modified Bauer Scoring System (mBS), in order to give an indication to a conservative, palliative or more aggressive surgical treatment to a metastatic spine disease. The modified Bauer classification results equal or inferior then 3 points in case of patients with short- or mid-term life expectancy (**Figure 1**).

**Figure 1.** Modified Bauer Scoring System and the prognostic score.

**1. Introduction**

422 Neurooncology - Newer Developments

Spinal cord involvement due to vertebral metastases is a frequent complication in cancer patients and metastatic lesions of spine can significantly condition their quality of life, potentially producing untreatable pain, vertebral fractures, or even neurological deficit due to spinal cord or radicular involvement [1, 2]. Spinal metastases are likely to increase their incidence because patients with cancer today can live longer, due to early detection, as well as to improvements in cancer treatment and care [3]. These lesions should be considered and treated both medically or surgically to prevent undesired sequelae, and to preserve or,

The spine is the third most common site for cancer cells to metastasize, following the lungs and the liver. Almost 70% of cancer patients are expected to have spinal metastasis. In case of symptomatic lesions, the majority (60–70%) are found in the thoracic region, while of the remainder, 20% are found in the lumbar region, and 10% are found in the cervical spine. More

Surgery of spinal metastases cannot be curative, but only palliative, aimed to preserve or, whenever possible, improve quality of life for patients with short- or mid-term life expectan‐ cy. In such cases, surgery is indicated for the stabilization of involved segments, for spinal cord

In the optic of reducing post-operative morbidity and accelerate the post-operative recovery, minimally invasive spine surgery (MISS) may represent the best option to achieve equiva‐ lent or superior outcomes to those of traditional open spine surgery, and to reduce the impact of surgery on critical patients with poor general and neurological conditions with short- or

**2. Patients with advanced cancer and thoraco-lumbar spine metastases**

The evaluation of clinical general and neurological conditions of patients with advanced cancer and spinal metastases is performed with the Karnowsky performance scale (KPS) and the American Spinal Injury Association (ASIA) scores. Total spine MRI and total body CT scan is mandatory in order to update the stadium of the disease and to planning the most correct

Approximately 90% of cancer patients with spinal metastases have bone and/or back pain, followed by radicular pain. Half of these patients have sensory and motor dysfunction, and more than half have bowel and bladder dysfunction. Five to 10% of cancer patients present with cord compression as their initial symptom; among these, 50% are non-ambulatory at

The initial functional neurological score, evaluated with ASIA score, is the most important prognostic factor for the neurological recovery of patients undergoing surgery. Surgery, in the

than 50% of patients with spinal metastasis have more than one level involved [6, 7].

whenever possible, improve the quality of their residual life [4, 5].

or root decompression, and for tissue diagnosis.

**2.1. Management and surgical indication**

diagnosis, and 15% are paraplegic [8].

mid-term life expectancy.

treatment.

To improve outcomes for patients with metastatic spine disease, many aggressive surgical strategies have been proposed. Nevertheless, an aggressive strategy is frequently associated with high morbidity and complication rates, and is not generally indicated in patients with poor general conditions and a limited life expectancy [9, 10].

These patients, in fact, often suffer from co-morbidities, malnourishment, diminished immunity, considerable pain, and they cannot face major surgery. Thus extensive surgical procedures or prolonged hospital stays are neither acceptable nor feasible in many of such patients.

Therefore, surgical risks must be weighed against life expectancy and quality of life, in order to justify standard surgical interventions.