Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_740_Библиотеки_им_академика_М_И_Перельмана

pain may also occur, for instance, after a partial damage due to constricting ligatures. The under­lying mechanisms of this type of neuropathic pain differ from acute postoperative pain based on tissue damage. Furthermore, if a previous repair was mesh based, an ongoing inammatory response to the inserted mesh (Sect. 41.3.2.1) may result in CPIP by progressive nerve injury [19, 20]. One rabbit study investigating micro­scopic inguinal nerve reactions to insertion of a prosthetic mesh found nerve axonal dilation and mild-to-severe loss of myelinated axons in nerve fascicles [21]. Both mechanisms may be respon­sible for neuropathic CPIP evolving in the long term in patients. On the other hand, due to long­lasting compression, nerves may already have

become damaged by the presence of the hernia for some time, resulting in myxoid histological changes of perineural oedema and an increased ratio of connective tissue to neural tissue [22].

A neurectomy or partial nerve lesion may inci­dentally lead to a traumatic neuroma formation. A neuroma can be intraoperatively recognized as a shiny, white, oval or round, rm-elastic palpa­ble nodule at the proximal cut end of the nerve or at a damaged part along its course (Fig.41.3). Of note, the location of the neuroma depends on the

26–28], but proper studies have not been per-

formed to date. The question why some develop a neuroma after surgical nerve injury while others do not is largely unanswered. Earlier research has not fully unveiled its aetiology; hence, more research on the pathogenesis and how to avoid neuroma formation is desirable. When a neuroma is identied and removed, success rates of the remedial surgery may be increased [26].

Nerve lesions may further lead to molecular changes in nociceptive neurons (C-bres) and non-nociceptive neurons (Aδ- or Aβ-bres) by releasing growth factors [30]. These nerve growth factors were found to inuence neighbouring uninjured nerves, which react by an upgraded expression of certain receptors such as vanilloid receptors (trpV1 receptors, responding to nox­ious heat), adrenoceptors (adrenergic receptors,

41.4). Why some patients develop deafferenta­tion pain while others do not is still unclear.

Long-lasting inguinal pain may result in cen­tral sensitization that can be extremely difcult to distinguish from other potential sources of pain. Centralized pain is independent of any peripheral drive [37] such as initiated by inguinal nerves and thus is refractory to peripherally directed treat­ments. Prolonged impulse stimulation along unmyelinated C-bre afferents may cause trans­neuronal morphologic changes to peripheral nerves (‘neuronal plasticity’). Peripheral nerve hyperexcitability may subsequently be caused by a lower threshold of nociceptor afferent periph­eral terminals, a phenomenon termed peripheral sensitization [30]. The extensive quantity and ongoing input resulting from peripheral sensiti­zation may lead to hyperexcitability of the spinal cord and morphological changes more proximal in the central nervous system and thus central sensitization [38–41]. Patients with centralized pain should be excluded from remedial, peripher­ally oriented surgery [16, 42].

Inserted meshes may not only lead to an ongo­ing low-grade chronic inammatory reaction but may also exert mechanical pressure or irritation possibly contributing to pain. The ‘anatomy’ of inserted mesh may change as creasing, wrinkling and folding may occur. This slow process increases mechanical pressure and may lead to a foreign body feeling. This feeling is reported by patients as something that is constantly bothering them as if a ‘wrinkled handkerchief is sitting in their pocket’. Previous studies suggested that up to half of the patients with a sutured mesh-based hernia repair report some kind of foreign body feeling in the groin [15, 28, 47]. Trials comparing a standard and a lightweight mesh have demon­strated a signicantly lower rate of foreign body sensation in the latter group [20, 45, 47, 48]. The lesser formation of brosis may correlate with the reduced foreign body feeling. Moreover, adhesions to surrounding structures may contrib­ute to the sensation.

Mesh-related pain may occur both after open and after laparo-endoscopic inguinal hernia repairs. In Western countries, laparo-endoscopic repairs such as TEP and TAPP are primarily rec­ommended, providing resources and expertise are available [49]. Approximately 15% of CPIP patients demonstrate a mesh-related pain after an open Lichtenstein repair [28]. The number of patients presenting with mesh-related pain is many times lower following laparo-endoscopic repairs [50]. An explanation for this difference is possibly provided by the position of the mesh in the preperitoneal space. This location is likely benecial not only in terms of evoking fewer cases of neuropathic pain [14, 51] but probably also for generating less mesh-related pain. It is thought, however, that the mesh may exert com­parable mechanical effects irrespective of mode of implantation, open or laparo-endoscopic [50].

Meshes have the tendency to wrinkle, fold and shrink up to 30% over time [52], and if this pro­cess proceeds, a so-called meshoma may be formed (Fig.41.4). A meshoma is dened by the operating surgeon [53]. Different gradations may be present, varying from a mass-like density to more subtle effects of mesh wrinkling or brosis [53]. A meshoma results in CPIP by a volume effect or by mechanical pressure on surrounding structures in the inguinal region. Insufcient xa­tion or insufcient dissection to make adequate room for the prosthesis may increase the risk of meshoma formation [54].

A meshoma is increasingly recognized as an important factor contributing to CPIP [55]. A recent study on CPIP patients after open inguinal hernia repair observed an up to 17% incidence of a meshoma [26]. Interestingly, identication of this unique pathologic nding following laparo­endoscopic hernia repair is less frequently described [50]. It should be appreciated that a meshoma following initial laparo-endoscopic her­nia repair looks different compared to open repairs, as subtle effects as wrinkling or small folds of the preperitoneal mesh may create pressure and mass effects. The lower grade of folding of the mesh in the preperitoneal space is possibly related to a rel­ative limited grade of exing and extending forces when compared to the groin region.

The mesh, being a meshoma or not, may also invade the surrounding structures and organs, resulting in serious damage (for instance, to the vas deferens or bladder). A typical case of inva­sion of the appendix by a meshoma (Fig.41.5), leading to chronic visceral pain in epigastrium with nausea, was previously described [56]. After removal of this mesh, visceral complaints (besides the pain) that had been present for many years also disappeared.

Dysejaculation (pain just before, during or following ejaculation) is known to profoundly affect a patient’s sexual activities [60]. The inci­dence of dysejaculation is approximately 3–4% following inguinal hernia repair [59–61] and may occur in male patients after both open and laparo­endoscopic repair techniques [60]. In one series of 100 men with CPIP, we encountered this phe­nomenon in some 30% [60]. The prevalence of ejaculatory pain is lower following laparo­endoscopic repair techniques compared to open repair [61].

The pathogenesis of dysejaculation involves injury to the vas deferens with or without damage to the inguinal nerves [59, 62, 63]. The vas may be compressed by the mesh or may be injured as a consequence of scar tissue. During ejaculation, peristalsis in the vas results in a post-obstructive dilation, triggering a spasm-related pain [64]. Mesh-related inammatory responses (Sect.

The analogue of dysejaculation in men is post­orgasm pain in women, seen of course in CPIP, but also after neuropathic pain in the so-called post-caesarean section pain syndrome. It is our experience that a pure neurectomy in these women can result in relieve of this specic sexual problem. Percentages of post-orgasm pain in women after hernia mesh repair are unknown.

the vas during open hernia repair techniques [70]. Injury due to the preperitoneal dissection or dis­ruption of the autonomic bres accompanying the vas can occur during laparo-endoscopic repairs, as well as placement of the mesh or addi­tional xation materials in proximity to these structures [54, 70–72]. As mentioned before, orchialgia is a combined CPIP syndrome that can include both neuropathic and nociceptive charac­teristics. The nociceptive causes for orchialgia are diverse and include postherniorrhaphy testic­ular ischemia, oedema, brosis of the spermatic cord and infection [70].

Concise history taking and an extensive physical examination provide the cornerstones in diagnos­ing inguinodynia. Clues for diagnosing the aeti­ology of CPIP are discussed below.

pain following a standard hernia repair develops later in the course of recovery or if pain persists after 3–6 months, a concise patient history and physical examination should indicate whether a patient suffers from neuropathic pain, from a nociceptive/inammatory pain (either mesh related or by other origins) or a combination of these or from pain due to a recurrent hernia. However, the differential diagnosis for groin pain in general is extensive, and not all CPIP does nec-

the occurrence of a traumatic neuroma should be considered. The use of sutures, tackers, staples and other prosthetic materials may indicate whether neuropathic pain is caused by injury from these.

corresponding the lowest Th10, Th11 and Th12 intercostal nerves.

Patients with a non-neuropathic CPIP usually report a throbbing or nagging pain located in a non-neuroanatomical area [77]. Once again, it is important to consider the type of inguinal hernia repair. Fixation methods and the inserted type of mesh are important clues associated with non­neuropathic pain syndromes. Studying previous operative reports is crucial. Moreover, the dura­tion of CPIP may contribute to the diagnosis.

On the other hand, sexual complaints includ­ing dysejaculation are solely diagnosed on the basis of patient history taking since no physical ndings can be noted. An intense burning, pain­ful sensation that occurs just before, during or after ejaculation [64] conrms the diagnosis of dysejaculation. Orchialgia is experienced as an intermittent, squeezing, deep ache in the testis

The French Neuropathic Pain Group developed a questionnaire (DN4) discriminating between neuropathic and non-neuropathic pain syndromes [79]. The DN4 questionnaire consists of both sensory descriptors and characteristics during physical examination [79]. This questionnaire was tested in a variety of neuropathic pain syn­dromes and demonstrated to be valid. Whether the questionnaire is also usable for distinguishing neuropathic from non-neuropathic CPIP patients needs to be investigated.

All of the CPIP pain syndromes are characterized by distinct clinical signs and symptoms that can be used to differentiate between them. First, the presence of sensory disturbances is a key diag­nostic feature for neuropathic CPIP and generally lacking in non-neuropathic pain.

Cold sensation can be assessed by the response