Body Mass Index Correlates with Skin to Spinal Canal Distance: A Large Retrospective Single‐Center Study

Abstract

BACKGROUND AND PURPOSE: Despite increasing demand for fluoroscopy-guided lumbar puncture (FG-LP), there is limited quantitative and epidemiological data on patients undergoing this procedure. Additionally, data are scarce on the correlation of iliac crest landmarks to the actual anatomical lumbar level (intercristal line). The aim of this study is to determine if (1) body mass index (BMI) correlates with skin to spinal canal distance (SCD) and (2) the iliac crest landmark correlates with the presumed anatomical landmark on cross-sectional imaging. METHODS: In this retrospective, single-center IRB-approved study, we assessed 495 patients who underwent FG-LP and had lumbar computed tomography/magnetic resonance imaging within 6 months of presentation. SCD was measured on the sagittal view at the L3-L4, L4-L5, and L5-S1 intervertebral levels. RESULTS: In our cohort of 495 adults (mean age ± standard deviation [SD], 53.2 ± 16.4 years), there was a statistically significant linear correlation between BMI and SCD at each intervertebral level. Mean ± SD (R 2) SCD at L3-4, L4-5, and L5-S1 was 6.7 ± 1.6 cm (.5486), 7.4 ± 1.9 cm (.5894), and 7.8 ± 1.9 cm (.5968), respectively. The intercristal line aligned with L3-L4, L4-L5, and L5-S1 in 2.1%, 72.4%, and 6.2% of patients, respectively. CONCLUSIONS: There was direct, positive linear correlation between BMI and SCD at clinically relevant lumbar disc levels. Furthermore, there is considerable anatomical variance in the intervertebral space that aligns with the superior aspect of the iliac crest.

The lumbar subcutaneous fat gradient in spinal anesthesia seen for morbidly obese patient with pre-procedure ultrasonography – A case report

“…Mahmoudi et al . [ 6 ] reported that the distance between the skin and the spinal canal, between the 3 rd and 4 th , 4 th and 5 th lumbar vertebrae, and 5 th lumbar vertebrae and 1 st sacral vertebrae is proportional to BMI and increases as it goes caudally. In our case, Figure 3 shows that the distance between the lumbar vertebrae and the skin increased caudally which suggests that the lumbar vertebrae and the skin are not parallel when the patient is seen from the side, but oblique caudally and spreads out [ Figure 4 ].…”

State‐of‐the‐art of lumbar puncture and its place in the journey of patients with Alzheimer's disease

“…31,52 Standard-length needles (70-90 mm) are used in adults, although longer needles may be needed in obese patients. 53,54 The use of longer needles makes the procedure more difficult because such needles are more flexible and thus have a tendency to divert off track. 31,55 This may necessitate multiple attempts at LP, causing local swelling, bruising, or muscle spasms, and increasing the risk of back pain.…”

“…Standard‐length needles (70–90 mm) are used in adults, although longer needles may be needed in obese patients 53,54 . The use of longer needles makes the procedure more difficult because such needles are more flexible and thus have a tendency to divert off track 31,55 .…”