Radical prostatectomy is a standard surgical procedure performed to remove the entire prostate gland and treat localized prostate cancer. The surgery aims to eradicate the cancer while minimizing impact on the patient’s quality of life. This goal led to the development of two primary surgical techniques: nerve-sparing and non-nerve-sparing radical prostatectomy. The difference between these approaches centers on the handling of specific nerve bundles that run near the prostate. Understanding the technical distinction between these two procedures is important for patients considering surgical treatment.
Anatomical Basis of Nerve Sparing
The ability to perform a nerve-sparing procedure relies on the precise location of the neurovascular bundles (NVBs), which are structures responsible for erectile function. These bundles are a complex, mesh-like network of nerves and small blood vessels. They are situated on the posterolateral surface of the prostate gland, where the prostate capsule meets the pelvic fascia.
The NVBs are encased within fascial layers, notably Denonvilliers’ fascia, making the dissection plane extremely narrow and challenging to navigate. A nerve-sparing prostatectomy (NSP) involves the meticulous separation of these bundles from the prostate before the gland is removed. This dissection must occur delicately to avoid traction or thermal injury, which can still compromise nerve function.
In contrast, a non-nerve-sparing prostatectomy (NNSP) involves the complete removal of the NVBs along with the prostate tissue. This technique is necessary when the cancer is suspected to have extended close to the edge of the prostate gland. Removing the bundles ensures the widest margin of tissue is taken, prioritizing complete cancer removal over nerve preservation.
Criteria for Choosing the Surgical Approach
The decision to attempt a nerve-sparing procedure is a surgical judgment guided by balancing oncological safety with functional preservation. The surgeon must first assess the risk of leaving cancerous tissue behind, known as a positive surgical margin, if the NVBs are spared. The most significant factor influencing this decision is the clinical stage and location of the tumor.
If imaging or biopsy results suggest the cancer is localized entirely within the prostate—known as organ-confined disease—NSP is generally considered a viable option. Modern multiparametric Magnetic Resonance Imaging (mpMRI) is used to estimate the risk of extracapsular extension (ECE), or cancer spread outside the capsule, and to measure the distance between the tumor and the NVBs.
Patient-specific factors also play a role in the decision-making process. Younger patients, typically those aged 65 or less, and those with good pre-operative erectile function have a higher likelihood of functional recovery after NSP. Patients with multiple severe comorbidities may also be less suitable candidates for a procedure where functional outcome is a primary goal.
If there is a high suspicion of ECE on one side of the prostate, the surgeon may elect for a unilateral nerve-sparing approach, removing the NVB on the high-risk side while attempting to preserve the bundle on the contralateral, low-risk side.
If the cancer is deemed aggressive or locally advanced, or if the tumor is located close to the prostate apex or base where the nerves are densely distributed, the surgeon will typically proceed with a non-nerve-sparing procedure to maximize cancer control. The patient must be informed that the final decision to spare the nerves may be made intraoperatively, prioritizing cancer clearance if the risk of a positive margin appears too high.
Post-Operative Functional Outcomes
The two functional outcomes affected by the surgical approach are urinary continence and erectile function. Regarding potency, the difference between the two approaches is substantial. Following a non-nerve-sparing prostatectomy, the proportion of patients experiencing impotence is very high, often reported to be around 92%.
A nerve-sparing approach dramatically improves the chances of retaining or recovering erectile function. For patients undergoing a bilateral nerve-sparing procedure, where both NVBs are preserved, the proportion of patients experiencing impotence is significantly lower, reported to be around 39%. The outcome is less favorable but still better than NNSP if only a unilateral nerve-sparing approach is possible, with impotence rates clustering around 59%.
Recovery of potency is gradual, often taking many months or even up to two years, and depends heavily on the extent of nerve preservation and the patient’s pre-operative function. Even when the nerves are anatomically spared, they may suffer temporary damage from stretching, swelling, or minor thermal injury during the dissection. A high baseline level of erectile function prior to surgery is the single most important predictor of successful recovery.
The impact of nerve sparing on urinary continence is less pronounced than on potency, though studies indicate better recovery rates with NSP. The nerves that control the urinary sphincter are distinct from the NVBs. Nerve-sparing procedures are associated with a lower incidence of post-operative incontinence compared to non-nerve-sparing procedures.
Bilateral nerve sparing has been shown to improve continence recovery in the early post-operative period. This is thought to be partly due to the preservation of accessory nerves and supporting tissue structures near the urethra, which contribute to urethral support and function. Ultimately, the trade-off remains: the nerve-sparing approach offers a greater probability of preserving functional quality of life, but it must be foregone if the risk of leaving cancer behind outweighs the benefit of functional preservation.