Peripheral nerve injuries (PNI) occur in 10% of combat casualties. In the immediate field-hospital setting, an insensate limb can affect the surgeon's assessment of limb viability and in the long-term PNI remain a source of considerable morbidity. Therefore the aims of this study are to document the recovery of combat PNI, as well as report on the effect of current medical management in improving functional outcome. In this study, we present the largest series of combat related PNI in Coalition troops since World War II.

From May 2007 – May 2010, 100 consecutive patients (261 nerve injuries) were prospectively reviewed in a specialist PNI clinic. The functional recovery of each PNI was determined using the MRC grading classification (good, fair and poor). In addition, the incidence of neuropathic pain, the results of nerve grafting procedures, the return of plantar sensation, and the patients' current military occupational grading was recorded.

At mean follow up 26.7 months, 175(65%) of nerve injuries had a good recovery, 57(21%) had a fair recovery and 39(14%) had a poor functional recovery. Neuropathic pain was noted in 33 patients, with Causalgia present in 5 cases. In 27(83%) patients, pain was resolved by medication, neurolysis or nerve grafting. In 35 cases, nerve repair was attempted at median 6 days from injury. Of these 62%(22) gained a good or fair recovery with 37%(13) having a poor functional result. Forty-two patients (47 limbs) initially presented with an insensate foot. At final follow up (mean 25.4 months), 89%(42 limbs) had a return of protective plantar sensation. Overall, 9 patients were able to return to full military duty (P2), with 45 deemed unfit for military service (P0 or P8).

This study demonstrates that the majority of combat PNI will show some functional recovery. Adherence to the principles of war surgery to ensure that the wound is clear of infection and associated vascular and skeletal injuries are promptly treated will provide the optimal environment for nerve recovery. Although neuropathic pain affects a significant proportion of casualties, pharmacological and surgical intervention can alleviate the majority of symptoms. Finally, the presence of an insensate limb at initial surgery, should not be used as a marker of limb viability. The key to recovery of the PNI patient lies in a multi-disciplinary approach. Essential to this is regular surgical review to assess progress and to initiate prompt surgical intervention when needed. This approach allows early determination of prognosis, which is of huge value to the rehabilitating patient psychologically, and to the whole rehabilitation team.

Introduction

We present a series of patients who have had secondary reconstruction of war injuries to the upper and lower limbs, sustained during the Iraq and Afghanistan conflicts.

A schwannoma is a benign nerve sheath tumour originating from schwann cells. It is the most commonly occurring peripheral nerve sheath tumour. The common sites of occurrence are the head and neck followed by the upper and lower limbs. Diagnosis is straightforward and is made clinically. Schwannomas of the tibial nerve pose a problem. The literature describes them as causes of chronic, intractable lower limb pain because their diagnosis is often delayed for several years. The main reason postulated is that a lump is not always palpable in the early phases and hence chronic cramping pain in the calf or foot is attributed to lumbosacral radiculopathy or local neuropathy.

We report the largest case series of twenty-five patients diagnosed with a tibial nerve schwannoma. Only three cases were diagnosed within a year of initial presentation. The mean time to diagnosis was eighty-six months. The most common site of pain was the sole of the foot (eighteen cases). A Tinel's sign was elicited in nineteen cases. MRI confirmed the diagnosis in all the twenty cases where it was performed. Surgical resection was performed in all cases yielding excellent results. Only one patient required further neurolysis for persisting pain.

In patients with a long history of neuropathic lower limb pain, where lumbar and pelvic lesions have been excluded, a high index of suspicion should be maintained for a peripheral nerve tumour. Delay in diagnosis is commonly due to lack of familiarity with peripheral nerve pathology and the absence of a palpable lump. The delay can result in numerous unnecessary medical and surgical interventions in this group of distressed patients. The Tinel's sign is the key to identifying a tumour of neural origin in the absence of a palpable lump. Surgical resection of the tumour remains safe and effective in providing symptomatic relief.

Objective: This study was performed to review the current treatment and outcome of extra abdominal fibromatosis in our hospital, supplemented by a current review of the literature.

Method: A retrospective study of 72 patients with fibromatosis seen at the Royal National Orthopaedic Hospital (RNOH) between 1980 and 2009 was performed. Patients were identified using the databases at the peripheral nerves injury (PNI) unit and the histopathology department. Medical and radiological records were reviewed.

Results: There were 72 patients treated at the Sarcoma and PNI units. 40 patients were primary referrals, and 32 more had operations at the referring hospital. An operation was not carried out in 5 patients. 48 patients were treated by operation alone and this was supplemented by adjuvant therapy in 19 patients. Recurrence was seen in 24 (50.0%) of the operation alone group and 10 (52.6%) in the operation and adjuvant therapy group. The rate of recurrence was lower with complete excision. However, complete excision was impossible in some cases because of extension into the chest or spinal canal, or involvement with the axial vessels and lumbosacral or brachial plexus.

Conclusion: We suggest that operative excision should seek to preserve function and that supplementary adjuvant therapy may reduce the risk of recurrence, although excision margin appears to be the most important factor. The aggressive, infiltrative behaviour of deep fibromatoses and the associated genetic mutations identified, clearly distinguish them from the superficial fibromatoses and makes their treatment more difficult and dangerous, especially where vital structures are involved. We agree with the recent recommendation that these lesions should be treated in regional soft tissue sarcoma units.

Over 75% of combat casualties from Iraq and Afghanistan sustain injuries to the extremities, with 70% resulting from the effects of explosions. Damage to peripheral nerves may influence the surgical decision on limb viability in the short-term, as well as result in significant long-term disability. To date, there have been no reports of the incidence and severity of nerve injury in the current conflicts.

A prospective assessment of United Kingdom (UK) Service Personnel attending a specialist nerve injury clinic was performed. For each patient the mechanism, level and severity of injury to the nerve was assessed and associated injuries were recorded.

Fifty-six patients with 117 nerve injuries (median 2, range 1–5) were eligible for inclusion. This represents 12.9% of casualties sustaining an extremity injury. The most commonly injured nerves were the tibial (19%), common peroneal (16%) and ulnar nerves (16%). 25% (29) of nerve injuries were conduction block, 41% (48) axonotmesis and 34% (40) neurotmesis. The mechanism of injury did not affect the severity of injury sustained (explosion vs gunshot wound (GSW), p=0.53). An associated fracture was found in only 48% of nerve injuries and a vascular injury in 35%. The presence of an associated vascular injury resulted in more severe injuries (conduction vs axonotmesis and neurotmesis, p< 0.05). Nerves injured in association with a fracture, were more likely to develop axonotmesis (p< 0.05).

The incidence of peripheral nerve injury from combat wounds is higher than previously reported. This may be related to increasing numbers of casualties surviving with complex extremity wounds. In a polytrauma situation, it may be difficult to assess a discrete peripheral neurological lesion. As only 35% of nerves injured are likely to have anatomical disruption, the presence of an intact nerve at initial surgery should not preclude the possibility of an injury. Therefore, serial examinations combined with appropriate neurophysiologic examination in the post-injury period are necessary to aid diagnosis and to allow timely surgical intervention. In addition, conduction block nerve injuries can be expected to make a full recovery. As this accounts for 25% of all nerve injuries, we recommend that the presence of an insensate extremity should not be used as an indicator for assessing limb viability.

Introduction: Shoulder relocation is commonly performed for the subluxating or dislocated shoulder secondary to Obstetric Brachial Plexus Palsy (OBPP). We have observed that even when relocation is performed at a young age, remodelling of the immature, dysplastic glenoid is often unreliable, resulting in recurrent incongruity and requiring treatment of the glenoid dysplasia.

Methods and results: In a series of 19 patients, we used a posterior bone block to buttress the deficient glenoid at the time of shoulder relocation. At a mean follow up of 28 months (6–73 months), we describe failure in at least 50% with erosion of the bone block, progressive subluxation and resultant pain.

A different technique of glenoplasty is now used. An osteotomy of the glenoid is performed postero-inferiorly, elevating the glenoid forward to decrease its volume. Bone graft, often taken from an enlarged and resected coracoid is then packed into the osteotomy and the whole assembly is held with a plate. In a series of 11 patients with a mean age of 6.7 years (1–18 years) we describe good results at short term followup, suggesting that this is a technique warranting further investigation.

Conclusion: We believe that where a deficient glenoid is found at surgery for relocation of the shoulder in OBPP, a glenoplasty should be performed at the same time whatever the age of the patient, as glenoid remodelling will not reliably occur. We no longer advocate posterior bone block in these cases as it has a significant failure rate.

Purpose: To investigate the mode of presentation, management and outcome of ischaemic contracture following a supracondylar fracture with a pink, pulseless hand.

Methods: We reviewed the database at our tertiary referral unit to identify cases over a 20 year period who had been referred for complications of a supracondylar fracture and/or a Volkmann’s ischaemic contracture.

Results: We identified 20 children with Volkmann’s ischaemic contracture following a supracondylar fracture. Of these, 4 patients (mean age 5, range 2–11) were referred to us with evidence of an ischaemic contracture but they had always had a pink albeit pulseless hand. Two of these 4 had undergone vascular exploration at 48 hours and at 72 hours but despite this developed an ischaemic contracture.

The 2 patients with the most severe contractures have undergone surgical intervention for their contracture, and 2 were managed conservatively with splinting. All 4 cases have residual problems with hand function (mean follow-up 5.5 years, range 2–11).

Conclusions: Volkmann’s ischaemic contracture should be a preventable condition. The pink albeit pulseless hand is at increased risk of ischaemic muscle and nerve damage and should not be ignored as the consequences are potentially devastating.

Significance: Clinicians must consider whether they feel that their management protocols for the pink, pulseless hand are robust and defensible.

To review the outcome of compound injury to the shoulder in which traumatic anterior dislocation is associated with concomitant rotator cuff tear and injury to the brachial plexus.

22 patients initially treated at the Peripheral Nerve Injury Unit since 1994 were reviewed from notes, telephone and clinically (n=13) where possible. 19 men and 3 women of average age 53 years were treated with a minimum 3-year follow up. All patients underwent exploration of the brachial plexus and nerve repair where required (graft n=5). Patients had either proven large cuff tear (n=13) or avulsion fracture of greater tuberosity with cuff injury (n=9). 7 of 13 cuff injuries and 7 of 9 tuberosity fractures had been repaired. Nerve injury at exploration was to circumflex (n=20), supra-scapular (n=12), musculocutaneous (n=6), or at the cord level (Posterior n=10, Lateral n=7 Medial n=8). Outcome measures were Berman pain score, sensation, muscle power (MRC grade), abduction, functional scores (Mallett and DASH) and return to work. Statistical analysis used tests for non-parametric data.

22 patients had exploration of the plexus. Most patients did not have an isolated nerve lesion (n=4). Increased depth of nerve lesion correlated with poorer functional outcome. E.g. for circumflex nerve injury (n=18), conduction block (n=8) vs. axonotmesis or neurotmesis (n =10) functional range of movement as assessed by Mallett score was significantly different; Mann Whitney U test p=0.043. Late exploration of nerve tended to correlate with poor outcome, as did late repair of rotator cuff, but not to statistical significance.

Our explorations have shown the nerve injury sustained in these patients to be more widespread than expected. We believe early exploration is vital to give an accurate diagnosis and predict outcome for the nerve lesion. This is particularly important in the presence of associated cuff injury where early repair confers favourable outcome.

Purpose: The relationship of pattern of injury to this region of the knee to the intraoperative finding of abnormal common peroneal nerve position and associated nerve palsy was studied.

Methods: 54 consecutive patients with posterolateral corner disruption requiring surgery were assessed prospectively by MRI, arthroscopic examination, and by operative display. The pattern of disruption, the status of the biceps tendon and any displacement of the common peroneal nerve were recorded.

Results: Of the 54 cases, there were 9 with CPN palsy, 18 were seen to have distal injuries (13 suffering a fibular head avulsion fracture and 5 biceps tendon avulsion with no fracture). There was a strong relationship (p< 0.001) between such distal posterolateral corner injury and abnormal position of the common peroneal nerve, as 16 of the 18 (90%) patients were seen to have abnormal nerve position. No proximal injury resulted in abnormal nerve position and only 1 was associated with CPN palsy. 7 of the 13 cases of fibular head fracture had CPN palsy, and 1 of the 5 distal soft tissue avulsions.

Conclusion: There is a strong association of distal soft tissue avulsion and fibular head fracture and CPN palsy in these injuries. Whenever such a distal injury is suspected, the surgeon operating in this region should expect an abnormal position of the common peroneal nerve and appreciate the increased risk of iatrogenic damage. Presumably since the CPN is intimately bound to the biceps tendon by deep fascia, proximal retraction of the biceps tendon results in displacement of the CPN to an abnormal position and accounts for the high incidence of nerve palsy.

Objective: The reported incidences of traumatic and iatropathic nerve injuries with supracondylar fractures in children are 12–16% and 6% respectively, with the majority recovering spontaneously. We performed a retrospective review of lesions referred to our tertiary unit to determine the incidence of surgical intervention.

Methods: Between 1997 and 2002, 37 neuropathies (associated with 32 supracondylar fractures) in 19 males and 13 females with an average age of 7.9 years were referred for further management. 8 fractures were classified as Gartland grade 2 and 24 as grade 3. All fractures were closed, with 2 treated non-operatively, 20 by closed reduction and percutaneous pinning and 10 by open reduction and internal fixation at the referring hospitals.

Results: The ulnar nerve was the most frequently injured (51.4%), followed by median (27%) and radial (21.6%) nerve palsies. 14 (37.8%) neuropathies were related to the fracture, while 23 (62.2%) were iatropathic. 10 patients (31.3%) required operative exploration while 3 (9.4%) were listed for surgery but were cancelled as they were recovering. Nerve grafting was used in 4 of the 10 operated cases, the donor nerve being the medial cutaneous nerve of the forearm in 3 and the superficial radial nerve in one. 26 patients (81.3%) had excellent outcomes, 5 (15.6%) good and 1 (3.1%) fair.

Conclusion: Although most had excellent outcomes, surgical exploration was required for nearly a third of the cases referred to our unit. This is in contrast to the current literature, which suggests that the majority of supracondylar neuropathies recover spontaneously.

Introduction: Traumatic and iatropathic nerve injuries complicate 6–16% of paediatric supracondylar extension fractures of the humerus. The majority recover spontaneously. This retrospective review of lesions referred to our tertiary unit determined the incidence of surgical intervention.

Methods: Between 1997–2002, 37 neuropathies (32 fractures) in 19 males and 13 females (mean age 7.9yrs) were referred for further management. 8 fractures were Gartland grade 2 and 24 grade 3. All fractures were closed. Two were originally treated non-operatively, 20 by closed reduction and percutaneous pinning and 10 by open reduction and internal fixation.

Results: The ulnar nerve was most frequently injured (19, 51.4%), followed by median (10, 27%) and radial (8, 21.6%) nerve palsies. 14 (37.8%) neuropathies were fracture-related but 23 (62.2%) were treatment-related. 10 patients (31.3%) required operative exploration. Three (9.4%) were listed for surgery but cancelled due to nerve recovery. Nerve grafting using either the forearm medial cutaneous nerve or the superficial radial nerve was necessary in 4 of 10 operated cases. 26 patients (81.3%) had excellent outcomes, 5 (15.6%) good and 1 (3.1%) fair.

Discussion: In contrast to current literature suggesting that 86 to 100% of supracondylar associated neuropathies recover spontaneously within 2 to 3 months, surgical exploration was required in over 30% of cases.

Introduction: To determine the aetiology of peripheral nerve injuries presenting to a specialist centre, identify the management strategies employed and discuss the functional outcome achieved.

Methods: Retrospective review of all children referred to this hospital between 1996–2003 with an acquired nerve injury. Obstetrical brachial plexus palsy was excluded.

Results: 100 nerve injuries (94 patients) were identified. The mean age was 9.9yrs (0.5–16yrs). 81 injuries involved the upper limb, 19 the lower limb. Most were due to low energy trauma and associated with fractures or their surgical management. 16% presented with autonomic sympathetic dysfunction, 10% with neuropathic pain. 43 patients underwent at least one surgical procedure. The operation was classified diagnostic in 5 (no surgically remediable lesion identified), therapeutic in 33 (surgical procedure could be expected to aid recovery) and reconstructive in 5 (no improvement in nerve function could be achieved; functional improvement achieved by other means). Excellent functional outcome only occurred in conservatively treated cases and in some treated by neurolysis. Nerve grafts and direct repairs were associated with good outcomes. Delayed surgery was associated with fair outcomes.

Discussion: Peripheral nerve injuries in children as in adults require careful, prompt attention to obtain the best outcome. Iatropathic injuries must be acknowledged.

An inability to extend the hallux following trauma is most often observed after direct laceration to the Extensor Hallucis Longus [EHL]. Primary repair, subsequent splinting and appropriate rehabilitation best deal with this type of injury. Damage to either the EHL muscle belly or the motor nerve to EHL are uncommon causes of the dropped hallux and present difficult reconstructive problems. Damage to the motor nerve branch to EHL in isolation is an uncommon problem and as far as we are aware surgery to address this pathology has not previously been described in the literature. This problem can occur after a penetrating injury, high tibial osteotomy or intramedullary nailing of a fractured tibia. We describe the operative procedure, technique and outcome in two cases of extensor hallucis longus to extensor digitorum communis (EDC) transfer to overcome this problem. A longitudinal skin incision is made just lateral to the tibia in the distal anterior part of the leg. The extensor retinaculum is divided and the EHL tendon identified and divided just distal to the EHL musculotendinous junction. The extensor digitorum communis (EDC) is then identified and the proximal stump of EHL woven into the EDC. A Pulvertaft weave technique is used and secured with 3/0 Ethibond suture. The appropriate amount of tension is placed on the repair by simulating weight bearing on the foot, ensuring the great toe remains in the neutral position. The extensor retinaculum is then repaired with 2/0 Vicryl and the skin closed with interrupted nylon sutures. The wound is infiltrated with 0.5% Marcaine to aid postoperative pain relief. A protected active motion rehabilitation program follows the surgery. We have used this technique in two cases, both have regained active extension of the hallux.

We describe seven cases of permanent neurological damage following interscalene block used in post-operative analgesia after operations at the shoulder. MRI, Nerve Conduction Studies and Quantitative assessments of function confirmed that in all there was infarction of the anterior spinal cord, resulting in a spinothalamic and corticospinal tract defect especially at segments C7, C8 and T1. We think that these lesions were caused by injury to radicular arteries. Domisse has demonstrated the anatomy of the radicular vessels joining the anterior spinal artery to supply the anterior two thirds of the cord. They are branches of the vertebral, ascending cervical and deep cervical arteries which pass through the inter-vertebral foramina with the C7, C8 and T1 roots predominantly. Chakravorty has shown that radicular vessels contribute to the blood supply of the lower cervical cord. Injury to them can cause ischaemia, leading to Anterior Spinal Artery Syndrome. We suggest tamponade of the radicular vessels by infusion of fluid under pressure deep to the prevertebral fascia as the main mechanism but neurotoxicity and vasospasm can be other possible explanations.

In a second group there was an additional interference with the vertebral artery presenting with transient bulbar and cranial nerve symptoms. We had 2 patients with such combined lesions. Complications of interscalene blocks are well documented but most are reversible and transient. In our cases the damage has been permanent and disabling. The innervation of the gleno-humeral joint is largely through the 4th, 5th and 6th cervical nerves and we suggest more appropriate placing of the blockade should be adapted and use of this technique for post-operative analgesia should be abandoned.

Malignant peripheral nerve sheath tumours (MPNSTs) constitute 10% of soft tissue sarcomas. A significant proportion arise in neurofibromatosis type 1 (NF1). Several publications have compared MPNST survival in sporadic and NF1 patients, without consensus on whether NF1 is an independent factor for poor prognosis.

Clinical and histological data from 135 proven MPNSTs were analysed from 2 national centres for soft tissue tumour surgery diagnosed from 1979 to 2000. 129 patients had follow-up data from 6 months to 21 years. 35 were from patients with NF1. Local treatment involved surgery in surgery in 95%, radiotherapy in 44% and chemotherapy in 21%.

NF1 patients were younger than those with sporadic tumours (median age 26 years vs 53 years, p< 0. 001). Overall MPNST survival was almost identical to that in soft tissue sarcomas as a whole, but was worse in NF1 than in sporadic tumours (33% vs 72% at 30 months [p< 0. 01], 17% vs 39% at 60 months, 6% vs 21% at 120 months). A trend towards shorter time to local recurrence was seen in NF1, but not time to metastasis. Superficial tumours gave improved prognosis. Tumour volume over 100ml was associated with worse survival (46% vs 91% at 30 months, p< 0. 02), as was histological grade (80% high grade vs 25% low grade at 60 months, p< 0. 01). In terms of location, a non-significant over-representation of NF1 MPNSTs in the sciatic and brachial plexii was identified.

NF1 and sporadic MPNSTs exhibited no difference in depth or tumour volume profile, although NF1 tended towards higher grade. Analysis of survival in only high grade tumours, however, still resulted in a significant survival disadvantage in NF1 (33% vs 70% at 30 months, p< 0. 01). Removal of brachial and sciatic plexus tumours from analysis did not affect survivorship profiles in NF1 and sporadic MPNSTs.

Grade, volume and tumour depth correlate with survival; only 7 of 45 patients with deep high grade tumours over 100ml volume were observed to survive beyond 2 years. MPNST survival is worse in NF1 than sporadic tumours. Grade, depth, site and volume differences could not explain this disadvantage.

We reviewed 1060 cases of OBPP prospectively at the Peripheral Nerve Injury Unit over 20 years. Data was collected for birth weight, maternal age, maternal height, maternal weight, duration of labour and associated difficulties, presentation, mode of delivery, neonatal problems, birth rank, race and social class.

The mean birth weight was 4.23 kg (Range 0.63–9.49 SD 0.72) compared to 3.47 Kg nationally [p < 0.05]. There was an association between severity of lesion and increase in birth weight.

Maternal age was 29.0 years in OBPP group [Range 14–43 SD 5.4] compared to 26.8 nationally [p < 0.05]. In 46.7% of the brachial plexus group, the mothers were > 30 years old. This was compared to 29.7% nationally.

The difference in maternal Body Mass Index (BMI) between patient group [27 with Range 14–44 SD 3.5] and national average of 25 was significant [p< 0.05]

Hypertension [11.8%] and diabetes [11.2%] were significantly [p< 0.05] higher than the national rate [6.4% and 1% respectively].

Shoulder dystocia occurred in 56% of the cases and was strongly associated with OBPP [p< 0.05].

Mean duration of labour nationally was 5.4 hours; in the patient group 10.8 hours [p< 0.05]

Breech presentation was more than three times the national average [p< 0.05]

Caesarean sections [2%] were less than national average [18%].

Instrumental deliveries [40.3%] were four times more than national rate. [P < 0.05]

The incidence of Neonatal asphyxia [22%] and Special Care Baby Unit [15.3%] was significantly [p< 0.05] higher than the national average [2% and 8% respectively]

Other factors did not prove to be statistically significant. These included; Social class, birth rank and ethnic origin.

We found that Birth weight, shoulder dystocia and body mass index are the most significant risk factors for obstetric brachial plexus plasy.

Study Design: To examine the innervation of the lumbar spine from patients with lower back pain, and spinal nerve roots from patients with traumatic brachial plexus injuries.

Objectives: To demonstrate the presence of nerve fibres in lumbar spine structures and spinal nerve roots, and determine whether they express the sensory neuronespecific sodium channels SNS/PN3 and NaN/SNS2.

Summary of background data: The anatomical and molecular basis of low back pain and sciatica is poorly understood. Previous studies have demonstrated sensory nerves in facet joint capsule and prolapsed intervertebral disc, but not in ligamentum flavum. The voltagegated sodium channels SNS/PN3 and NaN/SNS2 are expressed by sensory neurones which mediate pain, but their presence in the lumbar spine is unknown.

Methods: Tissue samples (ligamentum flavum n=32; facet joint capsule n=20; intervertebral disc n=15; spinal roots n=8) were immunostained with specific antibodies to protein gene product (PGP) 9.5, a pan-neuronal marker, SNS/PN3 and NaN/SNS2.

Results: PGP 9.5-immunoreactive nerve fibres were detected in 72% of ligamentum flavum and 70% of facet joint capsule but only 20% of intervertebral disc specimens. SNS/PN3-and NaN/SNS2-positive fibres were detected in 28% and 3% of ligamentum flavum and 25% and 15% of facet joint capsule specimens respectively. Numerous SNS/PN3 and NaN/SNS2-positive fibres were found in the acutely injured spinal roots, and some were still present in dorsal roots in the chronic state.

Conclusions: SNS/PN3 and NaN/SNS2-immunoreactivity is present in a subset of nerve fibres in lumbar spine structures, including ligamentum flavum and injured spinal roots. This is the first time that sensory nerve fibres have been demonstrated in the ligamentum flavum, and this raises the possibility that, contrary to the conclusions of previous studies, this unique ligament may be capable of nociception. Selective SNS/PN3 and NaN/ SNS2 blocking agents may provide new effective therapy for back pain and sciatica, with fewer side effects. Other novel ion channels are being studied in these tissues.