The effect of gigantomasty on vertebral degeneration: A computed tomography study

Abstract

The main reason for waist and back pain in patients with gigantomasty is increased thoracic kyphosis and lumber lordosis. These symptoms and abnormal spinal angulations regress after reduction mammoplasty operations. However, the effect of chronic mechanical stress caused by gigantomasty on the spinal degenerative process is not clear yet. In this study with computed tomography it is shown that degenerative spondylosis is more widespread and severe in patients with large breasts.

Keywords

Gigantomasty computed tomography degenerative spondylosis

1. Introduction

Degenerative spondylosis is seen less frequently in thoracic vertebrae than cervical and lumbar regions. In spite of frequently seeing alterations in thoracic vertebra due to spondylosis in routine radiologic imaging, symptoms are rarely seen in clinical practice [1]. Common causes of degenerative spondylosis are genetic inheritance, the aging process and mechanical loading [2, 3]. Mechanical stress mostly affects the lumbar region and spondylosis is frequently seen in this area [3]. The main reasons for mechanical stress are obesity, trauma, scoliosis and carrying excess load [2].

Gigantomasty is an idiopathic hypertrophy of breast glandular and fatty tissue that is related to genetic tendency and hormonal factors [4]. The hypertrophic breast tissue can cause various physical problems for women. The principal of these are skin irritation due to friction beneath bra straps and breast tissue, numbness in the fingers, decline in physical performance, respiration problems and body aches. These aches are generally in the head-neck, shoulder, back, and waist regions [5, 6]. It was shown that back and waist pain are related to spinal mechanical loading and thoracic kyphosis-lumber lordosis caused by gigantomasty. These symptoms generally regress after breast reduction surgery [5, 7]. The aim of breast reduction surgery is to decrease the impact of the breasts on the vertebral axis [7, 8].

As it is well known that gigantomasty causes back and waist pain due to abnormal angulations on the spinal axis and mechanical stress, the long-term effect of this mechanical stress on the spinal degenerative process is not clearly known. The aim of this study was to investigate the effect of gigantomasty on development of degenerative spondylosis.

2. Methods

2.1 Patients

Chest computed tomography (CT) scans of 785 female patients that were carried out in the radiology department of our hospital between January 2014 and January 2015 (13 months) were retrospectively evaluated. Images were acquired with a 16-row multi-detector CT scanner (Toshiba Alexion Advance, 16 slice, TSX-034A/1C, Japan) in the helical mode with 120 kV voltage, 50 mA per section, a 512 $\times$ 512 matrix and 5-mm slice thickness. The main indications for chest CT were pneumonia, trauma, asthma, pulmonary embolism, malignancy and mediastinal pathology. Some of these scans were performed without administration of intravenous contrast media, whereas others were performed with administration (Iohexol; Omnipaque, Nycomed, Oslo, Norway and Ioversol; Optiray, Covidien, Dublin, Ireland).

The field of view of chest CTs routinely constituted the lower neck and upper abdominal levels. Ninety patients were excluded at this step because of not including the upper abdominal levels. Abdominal slices of the remaining 695 patients were examined on the workstation of the CT scanner. Patients having abdominal pathologies such as ascites, masses, anterior abdominal wall hernia and soft tissue edema that could increase abdominal circumference were excluded. Abdominal circumference (AC) values were measured on the slice at the level of the lateral arch of the 12 ${}^{\text{th}}$ rib or on the previous slice. This value was used as representative of body mass index (BMI) [9]. Two-hundred and fifteen patients with AC lower than 80 (BMI $<$ 25) were determined. The remaining patients were excluded from the study because of obesity.

Multiplane reformatted CT images of 215 patients were acquired in soft tissue and bone kernels and were evaluated by focusing on the spinal region. Hospital records of these patients were analyzed. Subjects with a history of scoliosis, vertebral compression fracture, vertebral surgery, vertebral anomaly, spinal instrumentation, rheumatoid arthritis, ankylosing spondylitis and intervertebral disc herniation were excluded. The remaining 133 patients were included in the analysis.

Axial chest CT images of 133 patients were reviewed in soft tissue windows. Patients where both breasts were in the field of view and that lacked pathologic findings were determined. Total breast volumes (TBV) were calculated by adding volumes of each breast to each other, which were calculated separately on 3D breast reconstruction images acquired on the CT workstation [10] (Fig. 1). Patients were divided into three groups according to TBVs: small breast (SB: 0–799 gr), normal breast (NB: 800–1499 gr) and large breast (LB: $>$ 1499 gr). These three groups were statistically equal to each other with regard to age and AC values and the study was planned to be done with 99 patients in the end (Fig. 2). There were 35 (35.4%), 33 (33.3%) and 31 (31.3%) patients in the SB, NB and LB groups, respectively.

Figure 1.

Horizontal slice of breast tissue on the CT scan (A) and reconstructed 3D model of the breast (B).

Figure 2.

Patient selection.

2.2 Imaging evaluation

All patients were listed randomly to constitute a single group. Two radiologists, who were unaware of the breast volumes of patients and had at least 10 years of experience in CT interpretation, examined magnified midsagittal CT images including 1st thoracic to 1st lumbar levels. The degree of degeneration at each spinal level was determined using the Kellgren and Lawrence (KL) degeneration scale [11]. The scale was as follows: Grade 0: no radiographic feature of osteoarthritis; grade 1: minimal osteophytosis only; grade 2: definite osteophytosis with some sclerosis of the anterior part of the vertebral plate; grade 3: marked osteophytosis and sclerosis of the vertebral plates with slight narrowing of the disc space and grade 4: large osteophytes, marked sclerosis of the vertebral plates, and marked narrowing of the disc space (Fig. 3). The total degeneration grade (TDG), which was calculated by adding the KL degeneration grades of each spinal level, and the total number of involved levels (TNL) were determined for each patient. The relationship between these two variables and breast volumes were statistically analyzed.

Figure 3.

The degree of spinal degeneration according to the Kellgren and Lawrence scale; grade 1 (A), grade 2 (B), grade 3 (C) and grade 4 (D).

2.3 Statistical analysis

All statistical analyses were performed with IBM SPSS Statistics 22.0 software. Descriptive values of variables are expressed as mean $\pm$ standard deviation or median (min-max). Normal distribution of data was evaluated by Shapiro Wilk normalization test and Q-Q graphics. Group comparisons were made by One Way Analysis of Variance if numeric variables were distributed normally and by Kruskal-Wallis Analysis in case of abnormal distribution. Dunn test was used as a multiple comparison test if Kruskal-Wallis Analysis revealed a statistical difference between groups. Categorical intervariable relationships were analyzed with the exact method of the Chi-squared test. Relationships between numeric variables were analyzed with Spearman Correlation Analysis. All p levels less than 0.05 were considered to indicate statistical significance.

3. Results

The mean age of all women included in the study was 29 $\pm$ 7 years (18–40) and the AC was 68 $\pm$ 5 cm (57–80). Mean TBV was 1205 $\pm$ 680 (198–3413) gr. Mean TDG was 3.38 $\pm$ 3.95 (0–18) and mean TNL was 2.6 $\pm$ 2.51 (0–10). TDG and TNL were found to increase (rho $=$ 0.440; $p<$ 0.001 and rho $=$ 0.457; $p<$ 0.001, respectively) with increased breast volume independent of age and AC values on Spearman correlation analysis of 99 patients.

There were 35 (35.4%), 33 (33.3%) and 31 (31.3%) patients in the SB, NB and LB groups, respectively. The mean ages of the groups were 29 $\pm$ 7, 29 $\pm$ 7 and 29 $\pm$ 6 years ( $p=$ 0.855), respectively. AC values were 67 $\pm$ 5, 69 $\pm$ 5 and 69 $\pm$ 6 ( $p=$ 0.375), respectively. No statistically significant difference was present between the three groups with regard to these two parameters. The mean TBV’s of the three groups (SB, NB and LB) were 592 $\pm$ 152 (198–795), 1069 $\pm$ 147 (833–1380) and 2044 $\pm$ 525 (1500–3413), respectively.

TDG was significantly higher in the LB group (5 [0–18]) compared with the NB (2 [0–9]) and SB (0 [0–11]) groups ( $p<$ 0.001). TNL was significantly higher in the LB group (5 [0–10]) compared with the NB (2 [0–7]) and SB (0 [0–7]) groups ( $p<$ 0.001). No statistically significant difference was present between the SB and NB groups with regard to TDG and TNL (Tables 1 and 2).

Table 1
Comparision of TDGs between the breast volume groups (Kruskal-Wallis Analysis, the significance level is 0.05)

Groups	Test statistic	Std. error	Std. test statistic	Significance	Adjusted significance
SB – NB	$-$ 11.655	6.796	$-$ 1.715	0.086	0.259
SB – LB	$-$ 31.299	6.907	$-$ 4.531	0.000	0.000
NB – LB	$-$ 19.643	7.005	$-$ 2.804	0.000	0.000

Table 2

Comparision of TNLs between the breast volume groups (Kruskal-Wallis Analysis, the significance level is 0.05)

Groups	Test statistic	Std. error	Std. test statistic	Significance	Adjusted significance
SB – NB	$-$ 9.170	6.787	$-$ 1.351	0.177	0.530
SB – LB	$-$ 32.394	6.899	$-$ 4.696	0.000	0.000
NB – LB	$-$ 23.224	6.996	$-$ 3.320	0.001	0.003

4. Discussion

Osteophytes and osteoarthrosis are more widespread and severe in the human spine when compared with other primate species. The reason for this is the mechanical loading on vertebrae due to a bipedal posture [12]. Adams et al. [13] demonstrated in their study with cadavers that intervertebral joint degeneration is directly associated with age, but the intensity of degeneration is correlated with stress strain in these joints. The reason for the lower incidence of thoracic degenerative spondylosis compared to cervical and lumbar equivalents is the wider movement ability of cervical and lumbar regions compared to the thoracic region. With the help of the ribs, the thoracic levels are relatively free from biomechanical stress and instability [14]. We investigated the effect of high breast volumes on the spine in this study and think that examining the thoracic spinal level increased the reliability of our results, because it is relatively protected from spondylosis.

The principal reason for gigantomasty-related back and waist pain is altered body posture, which is associated with increased thoracic kyphosis and lumbar lordosis. The most important factor in reducing symptoms is probably the restoration of body posture. A decrease in symptoms after reduction mammoplasty and regression of back and waist pain in pregnant women after birth is related to this mechanism [5, 15, 16]. Furthermore, it was quantitatively shown that when pre- and postoperative radiologic measurements are compared, the thoracic kyphosis angle normalizes [7, 8] and the thoracolumbar compression force declines [6] in the postoperative period in patients undergoing reduction mammoplasty. We could not measure spinal angles because erect radiographs of the spinal column of our subjects were not present. However, higher TDG and TNL levels in the LB group compared to the NB and SB groups indicates that the effect of gigantomasty on aggravating thoracic kyphosis induces spondylosis. Thoracic spondylosis is probably more widespread and severe in patients with LBs because of this mechanism.

We used the Kellgren and Lawrence scale [11] to evaluate degeneration and this grading was done by taking into consideration vertebral end-plates and intervertebral disc spaces. Vertebral end-plates are important structures because they have neural innervation and are responsible for discogenic pain, accompany metabolite transport in the process of nourishment of discs and an injury to end-plates is usually associated with disc space involvement [17]. Furthermore, bone alterations (osteophytes and erosions) adjacent to the disc are strongly and substantially correlated with disc pathology [12]. For these reasons, we preferred to use this classification to evaluate spondylosis, which takes the condition of the end-plate into consideration.

Main limitations of our study: 1. It was a retrospective study completely based on CT images, so BMIs of patients could not be calculated. However, AC measurements were used, the reliability of which are well-known in the literature [9]. 2. Disc degeneration – a component of spondylosis-could not be evaluated, since magnetic resonance imaging is needed for this purpose. We used the KL scale, which takes subchondral bone alterations into consideration and gives indirect information on intervertebral discs [11]. 3. Breast volume measurements made based on CT images may not reflect real volumes exactly, but 3D breast reconstruction measurements have been shown to be correlated with real volumes in other studies [10]. 4. Spinal angles could not be measured because erect radiographs of the spinal column of subjects were not available. However, the effect of gigantomasty on spinal angles is an already known and discussed subject in the literature. Despite these limitations, to our knowledge, this study is the first to scrutinize the relationship between gigantomasty and vertebral degeneration, as well as to draw attention to gigantomasty as a known risk factor for vertebral degeneration.

In conclusion, gigantomasty seems to cause statistically significant degenerative spondylosis in the thoracic spine. It exhibits this effect probably by inducing mechanical load and thoracic kyphosis. Nevertheless, more clinical studies with wider case series are needed to support this hypothesis.

Conflict of interest

The authors declare that they have no conflicts of interest.

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The effect of gigantomasty on vertebral degeneration: A computed tomography study

Abstract

Keywords

1. Introduction

2. Methods

2.1 Patients

3. Results

Table 1 Comparision of TDGs between the breast volume groups (Kruskal-Wallis Analysis, the significance level is 0.05)

Conflict of interest

References

Table 1
Comparision of TDGs between the breast volume groups (Kruskal-Wallis Analysis, the significance level is 0.05)