人工陰莖植入手術

人工陰莖植入手術基本原理 (Rationale)

陰莖勃起時,血液經由陰莖動脈流入陰莖海綿體(corpora cavernosa),造成陰莖海綿體充血,同時壓迫住陰莖靜脈,讓血液不至於流出陰莖海綿體,才能達到陰莖長度及周徑都增加的堅挺雄姿,居功闕偉的構造要算是圍繞兩支陰莖海綿體的陰莖白膜(tunica albuginea) [Hsu et al, 1992; Hsu et al, 1994; Brock et al, 1997]。

多虧有堅韌且富彈性的白膜,陰莖鼓脹勃起時,才能達到堅硬的程度,這好比充氣後的輪胎;陰莖勃起時,尿道海綿體(corpora spongiosa)及龜頭(glans penis)也都有類似充血的情形,但因外圍缺乏堅韌的白膜,所以只能造成鼓脹、但未達堅硬的程度,這又好比是充氣後的汽球,因此在陰莖勃起堅硬時,才不至於壓迫尿道海綿體內的尿道而無法射精。

陰莖是能屈能伸的器官,關鍵就在於陰莖海綿體擁有這巧奪天工的結構。不管是任何原因引起的勃起功能障礙,治療的最終目的就是要使陰莖勃起達到一定的硬度,可以進行性行為。

人工陰莖植入手術就是將人工陰莖(penile prosthesis)植入陰莖海綿體,取代充血鼓脹的海綿體,但人工陰莖仍包覆在陰莖白膜內,使陰莖達到堅硬的程度,外觀仍與正常陰莖相差無幾,觸感也頗自然。

人工陰莖種類 (Penile Prosthesis Models)

半硬(semirigid)可折式(malleable)人工陰莖

這種基本款式的人工陰莖,由兩支棍棒狀人工陰莖體(rod-like cylinder)組成,分別植入左右側陰莖海綿體內。人工陰莖體內有一支機械式接合或可塑性的骨幹,可以用手向上或向下折彎此人工陰莖,進行性行為時將前段陰莖向上扳起,性行為後調至下垂狀態。此款式人工陰莖通常適用於明顯肥胖、雙手較不靈巧、腹部無法植入儲水囊(reservoir)(如曾接受廣泛的腹部手術、會陰手術、或腹膜透析)。

機械接合樣式(mechanical rod)的人工陰莖有Dura II (AMS),具可塑性樣式(malleable rod)的人工陰莖有650/600M (AMS)、Acuform (Mentor)。

這款人工陰莖由於零件少,有使用簡單、耐久性良好、不易故障等優點。由於無伸縮能力,起初病患會抱怨陰莖不會消軟,有收藏不便之憾;但現代人偏好穿著寬鬆的西褲或休閒褲,其實不太容易由外表看出,病患日久就習以為常了。目前有更新款可折式(malleable)人工陰莖,SPECTRA CONCEALABLE PENILE PROSTHESIS,可彎曲角度更大,隱藏性更好。

可膨脹式 (inflatable)人工陰莖

可膨脹式裝置包括植入左右側陰莖海綿體內成對的人工陰莖體,人工陰莖體可加壓充水而膨脹。人工陰莖體與儲水囊及調水泵浦(pump)間有管線(tubing)連接。根據不同的裝置,儲水囊可以植入腹部或陰囊內。有數種不同的款式。

單一可膨脹式 (unitary inflatable)人工陰莖:[Hydroflex、Dynaflex (AMS)]

這款人工陰莖為自容充水式(self-contained unit),集人工陰莖體、儲水囊及調水泵浦於一身,每一人工陰莖體包括了遠端部分、中央室(central chamber)和近端儲水囊。要勃起時,擠壓近端儲水囊讓中央室內充水2-3毫升,即可達堅硬勃起。將人工陰莖體折彎曲55 °以上即可啟動壓力開闢,讓水流回近端儲水囊,使人工陰莖體消軟。不過充水時固然能充份膨脹,但「放水」後卻無法「回到起跑點」。有些病患陰莖較寬大,人工陰莖體經常充水不完全,進行性行為時會有人工陰莖移動及彎曲的情形。另有些病患抱怨人工陰莖體不容易充水。此外,這款人工陰莖不適合植入曾有遠端尿道侵蝕(urethral erosion)病史的病患。

兩件可膨脹式人工陰莖[Ambicor (AMS) 、Mark II (Mentor)(2000年停產)]

這款裝置減少將儲水囊植入腹部的麻煩,使手術較植入三件可膨脹式人工陰莖更容易。其裝置包括植入左右側陰莖海綿體內成對的可膨脹人工陰莖體,藉由管線連接位於陰囊的調水泵浦及儲水囊。但其缺點在儲水囊容量有限,約15-20毫升。陰莖消軟時仍有多達5-10毫升的液體留在人工陰莖體內,造成消軟不完全。陰莖較大的患者批評此裝置容量小,不足以完全膨脹人工陰莖體;而陰莖較小的患者則抱怨此裝置很難完全消軟。這款人工陰莖適用於植入儲水囊有困難或禁忌的患者,例如曾經接受骨盆腔或腎移植手術。

三件可膨脹式人工陰莖 [700系列 (AMS)、Alpha 1和tTitan (Mentor)]

  • 這款裝置更加複雜,包括植入左右側陰莖海綿體內成對的可膨脹人工陰莖體、位於陰囊的調水泵浦及位於腹部的大型儲水囊。被證明是最令人滿意的裝置,硬度良好(甚至對於較大的陰莖) ,不論勃起或消軟,看起來最自然。此外,人工陰莖體消軟時可以減少對於白膜和陰莖海綿體產生的壓力。患有糖尿病、以前曾有人工陰莖體突出或感染的病患,適用這款裝置。
  • AMS-700系列提供Ultrex款式,可以使遠端增長、周徑膨脹,最多可增長20%;CX款式只能使周徑膨脹增大。CX款式最適合有疤痕組織或陰莖勃起彎曲的病患。此系列有一項創新製法就是InhibiZone,即人工陰莖外層矽膠表面用抗生素處理(minocyline hydrochloride和rifampin),初步研究顯示可以減少大約一半的感染率(下降到0.7%)[ Carson, 2004; Abouassaly et al, 2004]。
  • Mentor Alpha 1和Titan款式使用的人工陰莖體,可以使周徑膨脹增大。這兩款式已被證明非常耐用,而且不會在人工陰莖體上形成瘤狀膨出(aneurysm formation)。較新款式Titan和Alpha 1款式基本上是相同的,只是Titan款式增加親水塗層(polyvinylpyrrolidone),當人工陰莖裝置植入前浸泡在抗生素溶液中,可減少細菌附著,並使抗生素能吸附在人工陰莖裝置上。初步數據顯示可以明顯降低感染率。現在也都配備儲水囊鎖定閥(lockout valve),以減少自動充水膨脹的機率[Wilson et al, 2002; Hollenbeck et al, 2002]。

人工陰莖修復手術的可能性
(Possibility of revision surgery)

如果第一次手術沒有成功或有嚴重併發症,病患可能需要接受另外的手術。嚴重併發症包括感染、組織問題、陰莖組織受侵蝕或人工陰莖體破出、人工陰莖裝置本身故障。

討論 (Discussion)

人工陰莖植入手術是治療勃起功能障礙的最後方法,但因不是自然的治療方式,不論半硬式或可膨脹式的人工陰莖都有其體積,填入海綿體中絕不可能隱形而不影響陰莖自然的特性,許多病患對此猶豫不決。所以選擇時必須多加以比較不同種類人工陰莖的特性,考慮清楚後切勿三心二意;一旦選用就要視同己出,否則換品牌又得挨刀多受罪。無論如何,人工陰莖植入手術畢竟是泌尿科醫師手中的一張王牌,非不得已,不輕易使用。

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