Review paper Zbigniew Zylicz Consultant in Palliative Medicine, Dove House Hospice, Hull, United Kingdom Entrapment neuropathies Abstract Entrapment neuropathies are common in patients with advanced diseases including cancer. They may cause severe pain that is resistant to the treatment with known analgesics. This article reviews the syndromes of entrapment neuropathies relevant to palliative care. It also proposes simple treatment and aftercare. Be- ing able to diagnose entrapment neuropathies and to treat them effectively, potentially, may decrease the doses of opioids needed to treat the pain. Key words: entrapment neuropathy, pain in cancer, breakthrough pain, steroid injection, nerve compression, nerve trunk pain Adv. Pall. Med. 2010; 9, 3: 103–108 Introduction painful cramps which are often seen in motor neu- rone disease. Entrapment neuropathies (EN) are characterized ENs are only rarely discussed in textbooks on by spontaneous and/or paroxysmal pain felt in the cancer pain, perhaps because they are only occa- cutaneous or deep distribution of an involved sensory sionally caused by tumour growth directly. More or mixed nerve, or corresponding to the anatomical often they result from loss of elasticity of the sub- course of the nerve trunk or its branches [1]. Pain cutaneous tissues, muscle weakness and increased is spread into the distribution of other nerves for mobility of the joints and bones and are due to the same limb and even to that of corresponding the overuse of wasted muscles. This may happen nerves on the opposite side [2]. The pain is more when patients with advanced cancer decide to stay severe on movement and at those points where at home as long as possible and need to propel nerves can become trapped passing through narrow a wheelchair or walk on crutches. In general, because fibro-osseous tunnels or around bony prominences. patients with cancer tend to live longer, they also Clinically, these areas can be seen as trigger points or tend to develop all kinds of pain related to debility, “tic douloureux”. Spontaneous symptoms are de- including pain due to EN. Nothing specific is known scribed as unusual tactile and thermal feelings as- about the epidemiology of ENs, as this phenomenon sociated with numbness, tingling, pins and needles, is largely ignored in medical texts. Clinical descrip- burning, shooting, and electric shock-like sensations. tions of mononeuropathies have been known for The paroxysmal pain caused by EN may be re- many decades, but tend to be forgotten in academic sponsible for many so-called “breakthrough” teaching and may need to be rediscovered. One of pains encountered in patients with advanced can- the reasons for their being forgotten is the global cer, and needing specific diagnosis and treatment. trend to carry out fewer nerve blockades and to use Neuropathies affecting only motor nerves may cause more systemic analgesics. Address for correspondence: Zbigniew Zylicz Consultant in Palliative Medicine Dove House Hospice, Hull, HU8 8DH, United Kingdom e-mail: [email protected] Advances in Palliative Medicine 2010, 9, 103–108 Copyright © 2010 Via Medica, ISSN 1898–3863 www.advpm.eu 103 104 Advances in Palliative Medicine2010,vol.9,no.3 inPalliative Advances Table 1. Entrapment neuropathies encountered in patients with cancer Entrapment Clinical picture Place of entrapment Treatment neuropathy Greater occipital nerve One-sided or two-sided headaches Between the suboccipital Injection first of local anaesthetic and later muscles (oblique, methylprednisolone steroids (40–80 mg) semispinalis and trapezius) Supra-scapular nerve Pain on compression of the suprascapular area radiating to the tip of Suprascapular notch, Injection in the vicinity of the suprascapular the shoulder, shoulder joint immobility, sometimes giving a picture of sometimes the notch with a mixture of bupivacaine and “frozen shoulder”, atrophy of the supra- and infraspinatus muscles. glenohumeral opening methylprednisolone 40–80 mg [14–17]. May be caused by proximal muscle dystrophy due to dexamethazone Gentle physiotherapy to mobilize the shoulder is usually indicated. Occupational therapy, adjustment of crutches, wheelchairs and special household equipment are necessary www.advpm.eu Upper lateral This nerve can be compressed by the axillary nodes/tumours. When the In the axilla Continuous block has been tried [18]. cutaneous nerve of the axillary nerve is compressed, weakness of the deltoid and teres minor Radiotherapy to the axillary nodes is indicated upper arm (from axillary muscles may be apparent. These muscles may be atrophic. A small and usually effective nerve) patch of hyperalgesia may be noticed on the lateral aspect of the skin covering the deltoid muscle Intercostal nerves Hyperalgesia in the whole dermatome suggests root compression due Either in the course of Radiotherapy to vertebral metastases. A 5% to vertebral metastases. Hyperalgesia in only part of the dermatome vertebral foramen or at the lidocaine patch for 12–16 hours per day may suggest compression of the respective cutaneous branch by spasm peripheral trajectory of the applied directly to the area of hyperalgesia. of the paraspinal muscles (posterior cutaneous branch) or by nerve nerve Intercostal nerve blockade may be highly damage accompanying rib fracture effective, especially when ultrasound is used [19–20] Cutaneous ramus Pain on movement experienced in the lower part of the chest as well The nerve crosses the Injection of bupivacaine and of the XII subcostal as in the lateral part of the thigh. In these areas there may be a stroke iliac crest some 8–10 cm methylprednisolone to the tender nerve of hyperalgesia. Hyperalgesia may reach as low as the knee. This pain posteriorly from the iliac point on the iliac crest will differentiate may be apparent when the patient is forced to lie on one side because spina. Hence the tender between higher (paraspinal?) or peripheral of lung or liver pathology. Weight loss alone does not explain the point there compression mechanism of this EN. Frequently accompanied by iliohypogastric nerve EN (see below) [21, 22] Cutaneous ramus of the A stroke of hyperalgesia below this point may be present. Hyperalgesia This nerve crosses the iliac Injection of bupivacaine and ilio-hypogastric nerve of the lateral part of the mons pubis suggests involvement of the whole crest some 8 cm posteriorly methylprednisolone may differentiate the iliohypogastric nerve [21, 22] to the tender point of the site of compression (see text). The procedure cutaneous ramus of the XII may be difficult in some patients as they not subcostal nerve infrequently accumulate quite a lot of fat in this area Table 1. Entrapment neuropathies encountered in patients with cancer — continuation Entrapment Clinical picture Place of entrapment Treatment neuropathy Superior cluneal nerve This compression can be due to long-lasting supinal positioning when the patient is confined to bed. However, this nerve can become trapped in the iliolumbar ligament. Hyperalgesia of the upper medial area of the buttock may be observed [23] Found 7–8 cm from Injection of bupivacaine and methylprednisolone may be helpful. the median line, at However, when the points are symmetrical on both sides, one should the level of the L5 be careful as the pathology of the lumbar vertebrae may result in processus spinosus similar tender points. Relieving this pain may destabilize the spine and increase the risk of fracture Lateral cutaneous nerve Syndrome known as meralgia paraesthetica [24–26]. Pain, tingling The nerve is trapped under Injection of bupivacaine and www.advpm.eu of the thigh or a burning sensation is observed in the lateral thigh. Hyperalgesia the inguinal ligament, methylprednisolone to the place of does not extend as far as the knee. May be the result of lying flat in usually 2–3 cm medially tenderness [27–29]. If bilateral, the clinician bed. May be bilateral and below the iliac spina. should also think of the more proximal A tender point is localized entrapment in the spine. A 5% lidocaine there patch applied to the area of hyperalgesia may be effective Obturator nerve The patient may complain of pain in a small patch at the medial part A tender point is localized Injection of bupivacaine and of the thigh. Hyperalgesia may also be found there. Weakness of the in the upper part of the methylprednisolone to the tender point adductor muscles usually confirms the diagnosis [30] obturator foramen, below is usually helpful [31, 32]. Accuracy of Zbigniew Zylicz, and lateral from the this block can be increased by ultrasound. mons pubis The mechanism for this entrapment in patients with cancer is uncertain, so paravertebral or pelvic nerve compression should be considered [33]. Painful sacrum This happens in extremely cachexic patients lying in bed for days at One or more sacral foramina Inject first bupivacaine and Entrapmentneuropathies a time. One or more sacral foramina may be extremely painful, 20–30 minutes later methylprednisolone. suggesting entrapment of the cutaneous sacral nerves. Hyperalgesia in The injection of both drugs together may be the sacral dermatomes may be present extremely painful because of the lack of space [34] 105 Advances in Palliative Medicine 2010, vol. 9, no. 3 Neuropathic pain can be divided into two dif- ENs, providing they are recognized in time, are ferent categories. The first is nerve compression or usually reversible. Patients with a better progno- nerve trunk pain [1]. This neurogenic pain has been sis may undergo a neurosurgical decompression, attributed to increased activity in, as well as abnor- while patients in poor general condition will need mal processing of non-nociceptive input from the to rely on pharmacological treatment. The pain nervi nervorum [3]. With time, there may be a pro- is only partially sensitive to opioids and higher gressive loss of small and myelinated nerve fibres [4]. doses of these drugs are usually needed, especially It is unclear how important local inflammation is in when NSAIDs are contraindicated. The injection this process.