Painful Traumatic Neuromas in Subcutaneous Fat: Visibility and Morphologic Features With Ultrasound

OBJECTIVES

Subcutaneous neuromas usually result from trauma and may lead to dissatisfaction in patients with a trigger point, loss of sensitivity in the relevant territory of innervation, and spontaneous neuropathic pain. Confirming clinically suspected cases of neuroma may prove difficult. The objective of this study was to evaluate the visibility and morphologic features of traumatic subcutaneous neuromas of the limbs with ultrasound (US).

METHODS

Between January 2012 and August 2016, 38 consecutive patients clinically suspected of having subcutaneous neuromas were investigated with US. The diagnosis was confirmed on the basis of a focal morphologic abnormality of the nerve associated with trigger pain. Each neuroma was classified into 1 of 3 subtypes based on its injury pattern. The subtypes were terminal neuroma, spindle neuroma, and scar encasement, either isolated or associated with these subtypes.

RESULTS

Forty-four lesions were found in the 38 patients, including 29 spindle neuromas (65.9%), 14 terminal neuromas (31.8%) and 1 scar encasement with no nerve caliber abnormality (2.3%). Fifteen neuromas (35% of all neuromas) were associated with scar encasement. In 13 cases that required surgery, the diagnosis of neuroma or scar encasement could be surgically proven and confirmed the validity of the US findings.

CONCLUSIONS

Ultrasound can be used to show and classify subcutaneous nerves of the upper and lower limbs with high accuracy. The US trigger sign provides an indication of neuroma involvement in pain. This modality can play a substantial role both in the preoperative planning of neuroma surgery and in therapeutic US-guided procedures.

Anthropogenic Radio-Frequency Electromagnetic Fields Elicit Neuropathic Pain in an Amputation Model

Anecdotal and clinical reports have suggested that radio-frequency electromagnetic fields (RF EMFs) may serve as a trigger for neuropathic pain. However, these reports have been widely disregarded, as the epidemiological effects of electromagnetic fields have not been systematically proven, and are highly controversial. Here, we demonstrate that anthropogenic RF EMFs elicit post-neurotomy pain in a tibial neuroma transposition model. Behavioral assays indicate a persistent and significant pain response to RF EMFs when compared to SHAM surgery groups. Laser thermometry revealed a transient skin temperature increase during stimulation. Furthermore, immunofluorescence revealed an increased expression of temperature sensitive cation channels (TRPV4) in the neuroma bulb, suggesting that RF EMF-induced pain may be due to cytokine-mediated channel dysregulation and hypersensitization, leading to thermal allodynia. Additional behavioral assays were performed using an infrared heating lamp in place of the RF stimulus. While thermally-induced pain responses were observed, the response frequency and progression did not recapitulate the RF EMF effects. In vitro calcium imaging experiments demonstrated that our RF EMF stimulus is sufficient to directly contribute to the depolarization of dissociated sensory neurons. Furthermore, the perfusion of inflammatory cytokine TNF-α resulted in a significantly higher percentage of active sensory neurons during RF EMF stimulation. These results substantiate patient reports of RF EMF-pain, in the case of peripheral nerve injury, while confirming the public and scientific consensus that anthropogenic RF EMFs engender no adverse sensory effects in the general population.

Immunohistochemical analysis of the purinoceptor P2X7 in human lingual nerve neuromas

AIMS

Recent evidence suggests that the purinoceptor P2X7 may be involved in the development of dysesthesia following nerve injury, therefore, the aim of the present study was to investigate whether a correlation exists between the level of P2X7 receptor expression in damaged human lingual nerves and the severity of the patients' symptoms.

METHODS

Neuroma-in-continuity specimens were obtained from patients undergoing surgical repair of the damaged lingual nerve. Specimens were categorized preoperatively according to the presence or absence of dysesthesia, and visual analog scales scores were used to record the degree of pain, tingling, and discomfort. Indirect immunofluorescence using antibodies raised against S-100 (a Schwann cell marker) and P2X7 was employed to quantify the percentage area of S-100 positive cells that also expressed P2X7.

RESULTS

P2X7 was found to be expressed in Schwann cells of lingual nerve neuromas. No significant difference was found between the level of P2X7 expression in patients with or without symptoms of dysesthesia, and no relationship was observed between P2X7 expression and VAS scores for pain, tingling, or discomfort. No correlation was found between P2X7 expression and the time between initial injury and nerve repair.

CONCLUSION

These data show that P2X7 is expressed in human lingual nerve neuromas from patients with and without dysesthesia. It therefore appears that the level of P2X7 expression at the injury site may not be linked to the maintenance of neuropathic pain after lingual nerve injury.

Reconstruction of the human median nerve in the forearm with the Neurotube™

Reconstruction of the median nerve in the forearm traditionally has required multiple interfascicular interposition autologous nerve grafts. Recovery of two-point discrimination, even in young adults, has been reported rarely. Two patients, aged 43 and 61, are reported with 5-year follow-up of median nerve reconstruction in the distal forearm in which multiple interposition bioabsorbable polyglycolic acid conduits (Neurotube) were used to bridge the 3-cm nerve defects. Four separate 2.3-mm diameter, 4.0-cm long conduits were used in each patient. Sensory re-education was used for rehabilitation. Each patient recovered two-point discrimination with good localization in the thumb, index, and middle finger by 2 years after the nerve reconstruction. Both patients recovered abductor pollicis brevis function.

The tibial neuroma transposition (TNT) model of neuroma pain and hyperalgesia

Peripheral nerve injury may lead to the formation of a painful neuroma. In patients, palpating the tissue overlying a neuroma evokes paraesthesias/dysaesthesias in the distribution of the injured nerve. Previous animal models of neuropathic pain have focused on the mechanical hyperalgesia and allodynia that develops at a location distant from the site of injury and not on the pain from direct stimulation of the neuroma. We describe a new animal model of neuroma pain in which the neuroma was located in a position that is accessible to mechanical testing and outside of the innervation territory of the injured nerve. This allowed testing of pain in response to mechanical stimulation of the neuroma (which we call neuroma tenderness) independent of pain due to mechanical hyperalgesia. In the tibial neuroma transposition (TNT) model, the posterior tibial nerve was ligated and transected in the foot just proximal to the plantar bifurcation. Using a subcutaneous tunnel, the end of the ligated nerve was positioned just superior to the lateral malleolus. Mechanical stimulation of the neuroma produced a profound withdrawal behavior that could be distinguished from the hyperalgesia that developed on the hind paw. The neuroma tenderness (but not the hyperalgesia) was reversed by local lidocaine injection and by proximal transection of the tibial nerve. Afferents originating from the neuroma exhibited spontaneous activity and responses to mechanical stimulation of the neuroma. The TNT model provides a useful tool to investigate the differential mechanisms underlying the neuroma tenderness and mechanical hyperalgesia associated with neuropathic pain.

Neuroma formation in a rat median nerve model: influence of distal stump and muscular coating

BACKGROUND

The purpose of this study was to investigate neuroma formation in a rat median nerve model.

METHODS

In three groups, the median nerve was exposed and a gap was created. In the first group, a short gap of 1 cm (n = 12) was created; in the second, a long gap of 2 cm (n = 12) was created in the nerve. Another group was used to analyze the development of neuroma formation when the proximal stump was buried in adjacent muscle with an additional gap of 2 cm (n = 12). The use of different lengths should allow one to gain information about dilution effects of distal stump factors that may contribute to neuroma formation. Nine months later, specimens were gathered and histologically analyzed. The cross-sectional areas of neuromas were measured and the neural/connective tissue ratios were estimated.

RESULTS

The cross-sectional areas demonstrated that neuroma formation was significantly higher in the short-gap group than in the long-gap group, and smallest in the muscle-covered group. The percentage of neural tissue was highest in the muscle-covered and long-gap groups and lowest in the short-gap group.

CONCLUSIONS

These results demonstrate an association between neuroma formation and distal stump distance. This observation may be explained by the factors originating from the distal stump that were blocked when the proximal nerve stump was completely buried in the muscle. For clinical application, the authors recommend not only burying the proximal stump in a muscle but also surgically augmenting the gap between the proximal and distal stumps.

Relocation of painful end neuromas and scarred nerves from the zone II territory of the hand

This paper reports the results of treatment by proximal relocation of 46 painful end-neuromas or scarred nerves in 33 patients from the pre-defined Zone II of the hand. The relocated nerves included four palmar cutaneous branches of the median nerve, 17 dorsal branches of the ulnar nerves and 25 digital nerves. If no pain at the original site and no pain or only mild pain at the relocation site are considered an adequate treatment of these difficult problems, these relocation procedures achieve complete control of spontaneous baseline pain, complete control of spontaneous spikes of pain, 93% control of direct pressure pain, complete control of movement pain (excluding the extremes of movement of the wrist into extension, supination and, less frequently, pronation) and 96% control of hypersensitivity of the overlying skin.

Effects of collagen nerve guide on neuroma formation and neuropathic pain in a rat model

BACKGROUND

Posttraumatic neuroma formation is a major cause of neuropathic pain that can occur after elective surgery, amputation, or trauma. This study examined the use of biosynthetic collagen nerve guides to prevent the development of posttraumatic neuromas.

METHODS

Collagen nerve guides were applied after neurectomy in a rat sciatic nerve model in an effort to stimulate linear neuronal outgrowth and reduce random axon sprouting. Animals were monitored for evidence of neuropathic pain--autotomy scores were recorded for 8 weeks posttransection--after which proximal stumps were excised and processed for histologic analyses.

RESULTS

Moderate to severe autotomy was observed in 88% (7 of 8) of the control (neurectomy) animals. In contrast, 13% (1 of 8) of animals receiving collagen nerve guides developed autotomy, which was significantly less than controls (P < .01). Qualitative analyses of neurofilament and Schwann cell-labeled nerve sections showed a significant enhancement in Schwann cell migration away from the proximal stump and advanced linear axonal regrowth in the collagen nerve guide-treated animals.

CONCLUSIONS

Collagen nerve guides alter the regrowth of transected nerves and reduce the severity of symptoms associated with neuropathic pain.

Vanilloid receptor 1 (TRPV1) expression in lingual nerve neuromas from patients with or without symptoms of burning pain

The lingual nerve, a peripheral branch of the trigeminal nerve, can be damaged during the surgical removal of lower third molar teeth. This damage can lead to the development of dysaesthesia, with some patients complaining of burning pain. We investigated the hypothesis that vanilloid receptor 1 (TRPV1), a transducer of noxious heat stimuli, was involved in the development of this burning pain. Neuroma specimens were obtained from patients undergoing microsurgical repair of a damaged lingual nerve. Repair was undertaken where there was little evidence of spontaneous recovery, 7-41 months after the initial injury. Preoperatively the incidence of dysaesthesia was determined by reported symptoms and using visual analogue scales (VAS) for pain, tingling and discomfort. Nine neuromas were studied from patients with burning dysaesthesia and six from patients with a sensory deficit but no dysaesthesia. Indirect immunofluorescence for protein gene product (PGP) 9.5 and TRPV1 was used to quantify the percentage area of PGP 9.5 positive neuronal tissue that also expressed TRPV1. The results showed no significant difference between the mean percentage area of TRPV1 expression in neuromas from patients with or without burning dysaesthesia. Furthermore, there was no correlation between TRPV1 expression and the VAS scores for pain, tingling or discomfort. However, if data from all patients was pooled, there was a negative correlation between the level of TRPV1 expression and the time after initial injury. These data do not rule out involvement of TRPV1 in the aetiology of burning dysaesthesia following lingual nerve injury but suggest that TRPV1 at the injury site does not play a primary role.

Severe vaginal pain caused by a neuroma in the rectovaginal septum after posterior colporrhaphy

BACKGROUND

Traumatic vaginal neuromas are a rarely documented finding in the setting of vaginal pain after posterior colporrhaphy. They arise as a result of trauma or surgery and are often mistaken for scar tissue.

CASE

After a total vaginal hysterectomy and posterior colporrhaphy, a 32-year-old woman presented with debilitating vaginal pain, presumed to be secondary to scar tissue formation. Excision of the tissue from the rectovaginal septum revealed a traumatic neuroma. After the removal of the neuroma, the patient's vaginal pain resolved.

CONCLUSION

Traumatic neuromas may be a cause of significant point tenderness and thickened tissue after vaginal surgery or repair of obstetric lacerations. If conservative treatment methods have failed, surgical excision of the neuroma can be considered.

The potential role of nerve growth factor (NGF) in painful neuromas and the mechanism of pain relief by their relocation to muscle

Painful neuromas have been successfully treated by surgical procedures including relocation to muscle, but the underlying molecular mechanism remains unclear. Nerve growth factor (NGF) is secreted by tissues and promotes the expression of ion channels and neuropeptides in sensory neurons involved in pain transmission. We hypothesised that excess of NGF may lead to pain in neuromas and that the efficacy of surgical relocation results from deprivation of NGF, i.e. translocation from NGF-rich regions, particularly sub-cutaneous structures associated with injury or inflammation, to NGF-poor structures such as muscle or bone. Using immunohistological methods with primary antibodies to rhNGF, we report that NGF levels were elevated in 13 painful neuromas in comparison with six control nerves. However, in four painful neuromata re-located into muscle with pain relief, the NGF level was similar to that of controls. NGF levels suggest an explanation for the development of painful neuromas and the efficacy of relocation.

Coverage of painful peripheral nerve neuromas with vascularized soft tissue: method and results

OBJECTIVE

Our goals are to describe a method of treating painful peripheral nerve neuromas by means of vascularized tissue coverage, report the results in seven patients, and discuss the indications for this treatment modality. An analysis of pain, functionality of the affected body part, professional activities of the patients, and medications before and after surgery is presented.

METHODS

Seven male patients (mean age, 45.1 yr) with posttraumatic nerve injuries, who had developed painful stump neuromas or neuromas-in-continuity, and who had unsuccessfully undergone several treatment procedures, were selected for the surgery described here. The operation included resection of the stump neuroma (four patients) or neurolysis of the neuroma-in-continuity (three patients) and coverage of the nerve with a vascularized fascial, fasciocutaneous, or perforator flap (three pedicled regional flaps and four free flaps). A modified quadruple visual analog scale was used to quantify pain before and after surgical treatment. The mean follow-up was 16.6 months.

RESULTS

The mean values of the quadruple visual analog scale (pain now/typically/at its best/at its worst) before surgery were 6.5/6.5/4.7/7.9. These values changed to 0.3/0.4/0/0.9 at a mean follow-up of 16.6 months after surgery. Five patients returned to their original profession, one receives a pension, and one began a less demanding job after undergoing surgery. Six of the seven patients received opioids before surgery (one had a spinal cord stimulator). After surgery, all patients stopped taking regular pain killers and the spinal cord stimulator was deactivated in one; two patients still take nonsteroidal anti-inflammatory drugs occasionally, but not on a regular basis.

CONCLUSION

Vascularized soft tissue coverage of painful peripheral nerve neuromas seems to be an effective and attractive, but also complex, method of treatment. This option may be considered and reserved for patients who have already undergone several pain treatment modalities without success.

[The relationship between phantom limb pain and neuroma]

OBJECTIVES

We evaluated the effect of exploratory neurectomy on phantom limb pain (PLP) in patients who had PLP and neuroma findings in the amputated extremity.

METHODS

The study included 14 patients (13 males, 1 female; mean age 30 years; range 21 to 54 years) who developed symptomatic neurinoma and PLP following amputation of an extremity due to trauma (9 mine blasts, 5 traffic accidents). Postamputation period ranged from 2.5 to 17 years (mean 5.5 years). All the patients had PLP of varying intensity and neuroma symptoms causing the sensation of a small electric shock, aroused by application of prosthesis, contact with bed, or on palpation. The mean visual analog scale (VAS) score for PLP was 8.4 (range 7 to 10) before neurectomy. The mean follow-up was 71.5 months (range 44 to 98 months).

RESULTS

Complete recovery from PLP was achieved after neurectomy. Symptoms of neuroma completely disappeared during the follow-up period. Visual analog scale score was 0 in all the patients.

CONCLUSION

The best way to prevent postamputation neuromas and PLP is to cut the nerve as proximal as possible, allowing its retraction into the soft tissue, and leaving its end away from the stump.

Cold sensitivity in axotomized fibers of experimental neuromas in mice

Cold allodynia is a common complaint in patients with peripheral neuropathies. However, cold sensitivity of the different types of sensory afferents present in injured nerves is poorly known. We recorded activity evoked by cold in intact sensory fibers of the skin-saphenous nerve preparation and in axotomized sensory fibers of approximately 21 days-old neuromas of the saphenous nerve of mice, in vitro. Sixteen percent of the axotomized units responded to cooling with an accelerating discharge, which stopped immediately during rewarming. This response was similar to that observed in the intact cold-sensitive fibers. Temperature threshold distribution was broad in intact and axotomized cold fibers (30.7-22 degrees C and 34.5-14.5 degrees C, respectively). One-third of the axotomized cold-sensitive fibers were mechanosensitive and none of them displayed spontaneous activity at baseline temperature. In contrast, 33% of intact cold-sensitive fibers exhibited low rates of ongoing discharges. In 60% of the cold-sensitive, axotomized units, cold threshold was shifted towards warmer values by the TRPM8 agonist L-menthol. Seventy percent of axotomized, cold-insensitive units developed sensitivity to cold when exposed to 4-aminopyridine and their mean cold threshold (approximately 28 degrees C) was unaffected by menthol. Their response properties differed greatly from those of cold-sensitive units. In conclusion, the transducing capacity to cold stimuli is substantially recovered in neuromas. Furthermore, axotomized fibers maintain the 4-AP-sensitive, voltage-activated, transient potassium conductance that counteracts the depolarizing effects of cold in the majority of intact, cold-insensitive primary afferents. Our results indicate that injured nociceptors do not develop abnormal cold sensitivity, suggesting that other mechanisms underlie the cold-induced allodynia following peripheral nerve injury.

Both positive and negative factors regulate gene expression following chronic facial nerve resection

Previously, we reported that following a chronic nerve resection, removal of the neuroma reversed the atrophy, increased the number of countable motoneurons and resulted in the re-expression of GAP-43 and alpha tubulin mRNA. In the present study, we questioned whether this response was due to the removal of the neuroma, or a result of factors such as neurotrophins, produced at the injury site. To test this hypothesis, 10 weeks after axotomy, the axonal transport blocker colchicine or, glial derived neurotrophic factor (GDNF) was injected proximal to the neuroma. The injection of GDNF or colchicine elicited an increase in motoneuron size and in GAP-43, but not alpha tubulin, mRNA. These data suggest that in addition to factors produced at the injury site, the neuroma acts as a source of target-like repressive signals that when removed results in an increase in gene expression and motoneuron size. To analyze the regenerative potential of chronically resected motoneurons, mice without a previous nerve injury and mice with a chronic resection received a pre-degenerated segment of sciatic nerve attached to the proximal facial nerve stump. Axons from both the chronic and acute groups grew into the grafts, however, significantly more retrogradely labeled motoneurons were counted in the acute group compared to the chronic resection group. No difference in motoneuron cell size was observed between the two groups of regenerated neurons. Therefore, despite severe atrophy, many of the surviving mouse facial motoneurons retain the propensity to extend their axons when provided with the appropriate environment.

Treatment of end-neuromas, neuromas-in-continuity and scarred nerves of the digits by proximal relocation

This paper reports the results of treatment by proximal relocation of 104 painful nerves in 57 digits in 48 patients. These included 86 digital nerves and 18 terminal branches of the superficial radial nerve and the dorsal branch of the ulnar nerve. Eighty-three were end-neuromas and 14 were neuromas-in-continuity, of which nine followed nerve repair and five occurred following a closed crush injury. Seven were painful as a result of tethering in scarred tissue. Eighty nerves (77%) required a single relocation and 24 (23%) required more than one operation. Ninety-eight per cent of nerve relocations achieved complete pain relief at the primary site. One patient had mild pain on pressure at the primary site after relocation of two nerves from this site. Over 90% of the nerves had no spontaneous pain, pain on movement or hypersensitivity of the overlying skin at the final site of relocation. However, the incidence of mild or no pain on direct pressure at the site of nerve relocation was lower at 83% as relocated nerves, although traumatized less often at the sites chosen for relocation, can still be painful on direct pressure.

Surgical repair of brachial plexus injury: a multinational survey of experienced peripheral nerve surgeons

Object. Brachial plexus injuries (BPIs) are often devastating events that lead to upper-extremity paralysis, rendering the limb a painful extraneous appendage. Fortunately, there are several nerve repair techniques that provide restoration of some function. Although there is general agreement in the medical community concerning which patients may benefit from surgical intervention, the actual repair technique for a given lesion is less clear. The authors sought to identify and better define areas of agreement and disagreement among experienced peripheral nerve surgeons as to the management of BPIs.

Methods. The authors developed a detailed survey in two parts: one part addressing general issues related to BPI and the other presenting four clinical cases. The survey was mailed to 126 experienced peripheral nerve physicians and 49 (39%) participated in the study. The respondents represent 22 different countries and multiple surgical subspecialties. They performed a mean of 33 brachial plexus reconstructions annually. Areas of significant disagreement included the timing and indications for surgical intervention in birth-related palsy, treatment of neuroma-in-continuity, the best transfers to achieve elbow flexion and shoulder abduction, the use of intra- or extraplexal donors for motor neurotization, and the use of distal or proximal coaptation during nerve transfer.

Conclusions. Experienced peripheral nerve surgeons disagree in important ways as to the management of BPI. The decisions made by the various treating physicians underscore the many areas of disagreement regarding the treatment of BPI, including the diagnostic approach to defining the injury, timing of and indications for surgical intervention in birth-related palsy, the treatment of neuroma-in-continuity, the choice of nerve transfers to achieve elbow flexion and shoulder abduction, the use of intra- or extraplexal donors for neurotization, and the use of distal or proximal coaptation during nerve transfer.

The treatment of painful neuroma on the lower extremity by resection and nerve stump transplantation into a vein

Lower extremity neuroma resection with nerve stump transposition into a vein was employed in eight patients (five male, three female). The neuromas resulted from amputations (four patients), vein stripping procedures (two patients), tumor resection, and toe-harvest for thumb reconstruction. Follow-up averaged 17 months (range, 8-37). Four of the patients experienced complete and permanent relief of pain; in three patients mild pain recurred within 3 months. All of these patients were satisfied with the result and did not request further treatment. In one case, a painful neuroma recurred. Our results suggest the possibility of inhibiting the formation of painful neuromas by nerve transposition into a vein. Further use of this method is encouraged.

Retrograde regeneration following neurotmesis of the ulnar nerve

A 41-year-old woman experienced a gunshot wound to the forearm with neurotmesis of the ulnar nerve. Surgery 9 months later revealed a neuroma-in-continuity in the midforearm. Intraoperative nerve stimulation failed to elicit direct nerve responses or motor responses from the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles. However, neurotonic discharges in response to mechanical irritation of the neuroma were recorded in the FDI, but not the ADM. Surprisingly, after resecting the ulnar nerve distal to the neuroma, neurotonic discharges were still elicited in the FDI following perturbation of the neuroma. Moreover, neurotonic discharges were elicited during ulnar nerve resection 2 cm proximal to the neuroma. No anastomoses or anomalous branches were noted. The findings suggest that regenerating fibers did not reach the FDI through the distal nerve segment. Rather, we speculate that nerve fibers regenerating at random, or impeded by scar tissue, contacted the proximal nerve portion, at which point growth became polarized in a retrograde direction. Retrograde regeneration may have proceeded to a branch point in the forearm (possibly an undetected anomalous branch or fibrous adhesion), where growth of regenerating fibers extended outward into surrounding damaged tissue planes before redirecting distally to reach the FDI.

The tetrodotoxin-resistant Na+ channel Nav1.8 is essential for the expression of spontaneous activity in damaged sensory axons of mice

The tetrodotoxin-resistant sodium channel alpha subunit, Nav1.8, is exclusively expressed in primary sensory neurons and is suggested to play a role in the generation of ectopic action potentials after axonal injury and thereby contribute to neuropathic pain. Here we investigated the involvement of Nav1.8 in ectopic impulse generation in damaged axons by examining spontaneous activity and mechanosensitivity in neuromas formed by section of the saphenous nerve in Nav1.8 null mice and in their wild-type littermates. We recorded 522 identified units from 24 neuromas in vitro at two time points, 8-11 days (median 10 days) and 19-29 days (median 22 days) post-operatively. At approximately 10 days, neither genotype showed spontaneous activity, but a significantly higher proportion of fibres were mechanosensitive in wild-type (54%) compared to Nav1.8 null neuromas (18%). At approximately 22 days, 19% of fibres recorded in wild-type neuromas showed spontaneous activity, whereas only one fibre of the 238 (0. %) recorded in neuromas taken from null mice showed ongoing activity. In recordings at approximately 22 days, a similar proportion of fibres were mechanosensitive in wild-type and Nav1.8 null neuromas (51 and 46%, respectively). We conclude that Nav1.8 is essential for the expression of spontaneous activity in damaged sensory axons, and may also contribute to the development of ectopic mechanosensitivity.

["Square sail" flap in median nerve lesions at the wrist. Anatomical elements and review of twenty operated cases]

INTRODUCTION

Following an anatomical study on the vascular supply of the upper limb, we propose a new adipo-fascial flap at the wrist. The fat pad of pronator quadratus lies over the muscle and is vascularised by a recurrent branch arising from the anastomotic "cross-road" of the anterior interosseous, radial and ulnar arteries, at the radio-carpal joint. The peripheral extensions of the adipose tissue have to be anchored to the palmar fascia of the muscle in order to hoist the flap as a "square sail". The flap is then distally rotated in order to cover the traumatized median nerve segment at the wrist, for 2.5-3 cm of length.

METHODS

The authors present a review of the clinical applications (1995-2001) on painful neuromas of the median nerve at the wrist, where traumatic and iatrogenic injuries frequently occur. The surgical procedure consists of external neurolysis followed by coverage of the nerve using this vascularised flap.

RESULTS

The results confirm the usefulness of vascularised fat flaps in creating an optimal perineural environment in terms of biological and mechanical quality. The advantage offered by this particular local flap is that it can be speedily raised. Because of its limited length the flap is only able to cover the median nerve at the level of the carpal tunnel: its indications are therefore very selective but not rare, due to the frequency of median nerve injuries at this level.

DISCUSSION

Clinical results were very satisfactory: in the twenty cases reviewed, resolution of the symptoms of algodystrophy and causalgia was consistently observed, sometimes to an extraordinary degree, and associated with an improvement in the neurological deficit.

Treatment of painful peripheral neuroma by vein implantation

Painful neuromas form on cutaneous nerves as a result of trauma, pressure, stretch or entrapment. Since the earliest descriptions of neuromas, proposed treatments have been met with poor results and controversy. The myriad of treatments described include: simple division of an affected nerve, implantation into muscle or bone, silicon sleeves and caps, repeated injection of steroids, end-to-side neurorrhaphy, medication and vein caps to name a few. Due to encouraging recent reports of treatment of painful neuromas by vein implantation, the authors describe a simple technique to achieve this surgical goal. As veins are readily accessible due to their proximity in the neurovascular bundle, they serve as a ready source for grafting. The advantages include minimisation of trauma to bone and muscle as compared with previous treatment techniques and the relative ease of the method.

Retinal Remodeling in Inherited Photoreceptor Degenerations

Photoreceptor degenerations initiated in rods or the retinal pigmented epithelium usually evoke secondary cone death and sensory deafferentation of the surviving neural retina. In the mature central nervous system, deafferentation evokes atrophy and connective re-patterning. It has been assumed that the neural retina does not remodel, and that it is a passive survivor. Screening of advanced stages of human and rodent retinal degenerations with computational molecular phenotyping has exposed a prolonged period of aggressive negative remodeling in which neurons migrate along aberrant glial columns and seals, restructuring the adult neural retina (1). Many neurons die, but survivors rewire the remnant inner plexiform layer (IPL), forming thousands of novel ectopic microneuromas in the remnant inner nuclear layer (INL). Bipolar and amacrine cells engage in new circuits that are most likely corruptive. Remodeling in human and rodent retinas emerges regardless of the molecular defects that initially trigger retinal degenerations. Although remodeling may constrain therapeutic intervals for molecular, cellular, or bionic rescue, the exposure of intrinsic retinal remodeling by the removal of sensory control in retinal degenerations suggests that neuronal organization in the normal retina may be more plastic than previously believed.

Implantation of multiple intercostal nerve neuromas in lesioned spinal cord-repair, regeneration and rehabilitation strategies

Multiple intercostals nerve neuromas are surgically implanted in the lesioned spinal cord by bridging transaction lesions at T6 or T8 by removing one centimeter of spinal cord. In these experiments one to four intercostals nerves with origin proximal to the transection and the distal stumps, the neuroma was implanted distal to the transection. These procedures plus rehabilitation resulted in enhancing of regeneration of axons in the spinal cord lesion and dogs developed standing, stepping and reflex walking locomotion. Surgical resection of the implanted nerve resulted in paraplegia. Multiple nerve implants bridging the transaction of 34 mature female dogs. A pattern of neurological deficits developed when a sequence of resection of the implanted nerves were performed. If four nerves were implanted and one nerve resected usually no deficits were observed. When the second nerve was resected certain deficits were observed. When three nerves were resected some dogs became paraplegic, and some dogs showed increased sign of paraplegia but were not completely paralyzed and showed hind limb movements but no weight bearing. When four nerves were resected full paraplegia was observed.

Ischemia and failed regeneration in chronic experimental neuromas

Neuromas are generally considered to be swollen uniform collections of uncontrolled aberrantly sprouting axons. In early experimental neuromas, there are substantial rises in local blood flow associated with their formation, but human studies of chronic lesions have suggested that neuromas develop ischemia and become impediments to regeneration. The issue is important because traumatically severed human nerves are frequently considered for repair some time after injury, when neuroma formation has occurred. In this work, we examined local perfusion, axon penetration and other characteristics of long-term (6 month) experimental neuromas created by sciatic nerve transection and resection of the distal sciatic nerve and its branches. The scenario was designed to model prior transection in a human nerve, where late surgical reconnection might be contemplated. Local blood flow in the extrinsic plexus of neuromas, examined using a laser Doppler flowmetry probe, declined in distal portions of the stump to values considerably lower than observed in intact nerves. Intrinsic blood flow near the stump tip, examined using microelectrode hydrogen clearance polarography was highly nonuniform and included zones with very low perfusion. Correlated with these findings were nonuniform histological features with zones of absent axons and blood vessels, progressive distal disorganization, marked declines in distal axon penetration, nonremodelled microfascicles and persistent expression of 'regenerative' axon and Schwann cell markers. Uncontrolled axon sprouting was not a feature. Longstanding neuromas include zones of relative ischemia and limited axon penetration that develop in the absence of nerve trunk reconnection. These features would limit their suitability for later repair.

Accumulation of PN1 and PN3 sodium channels in painful human neuroma-evidence from immunocytochemistry

BACKGROUND

The axolemmal distribution and density of voltage-gated sodium channels largely determines the electrical excitability of sprouting neurites. Recent evidence suggests that accumulation of sodium channels at injured axonal tips may be responsible for ectopic axonal hyperexcitability and the resulting abnormal sensory phenomena of pain and paresthesias. For future improvement in pain management it is necessary to identify structurally significant generators of autorhythmicity. A first step in this regard will be to determine the predominant types of sodium channels in injured axons. The opportunity to test human specimens from painful and non-painful neuroma is of great value.

METHODS

We employed immunocytochemical methods to investigate if two types of highly specific voltage-gated sodium channel subtypes could be detected in sections of human neuroma.

FINDINGS

Both subtypes of sodium channels PN1 and PN3 accumulated abnormally in human neuromas. The immunoreactive pattern was more pronounced in painful neuromas. This is in contrast to previous reports that focused either on PN1 or PN3 as main generators of hyperexcitability induced pain.

INTERPRETATION

Both, PN1 and PN3 seem to be involved in hyperexcitability induced pain. It can be expected that a variety of other highly specific voltage gated sodium channel subtypes will be detected in regenerating peripheral nerve in the near future, which contribute to the development of neuropathic pain states. Thus, in order to therapeutically control hyperexcitability induced neuropathic pain, it might be worthwhile to develop pharmaceuticals that can selectively block different sodium channel subtypes and subunits.A review of the role of sodium channels in neuropathic pain is implemented in the discussion.

Social variables affect phenotype in the neuroma model of neuropathic pain

When the degree of genetic determination of a trait (i.e. its heritability) is high, one tends to presume that environmental factors will not modify its expression by much. Contrary to this expectation, we show here in rats that a psychosocial-behavioral variable, the identity of cagemates, can largely over-ride genetic predisposition to pain behavior. We used selection-line rats that consistently show high (HA) or low (LA) pain phenotype (autotomy) in the neuroma model of neuropathic pain. Normally, HA animals show autotomy after nerve injury while LA animals do not. However, when caged together with HA rats, LA rats showed high levels of autotomy. This occurred even when the individual HA cagemates were familiar preoperatively, and it did not depend on the actual performance of autotomy by the HA rats. Indeed, cage bedding soiled by HA rats was sufficient to induce a modest level of autotomy in LA animals. Chemical cues associated with HA rats, perhaps in combination with behavioral characteristics, are apparently able to induce pain phenotype despite the powerful protection otherwise rendered by the LA genotype. Social factors must be considered in behavior-related research on rodents that have undergone genetic modification. More generally, the overwhelming influence that psychosocial-behavioral variables have on pain perception, and on pain behavior, in humans may have evolutionary roots deeper than has previously been appreciated.

Receptors for NGF and GDNF are highly expressed in human peripheral nerve neuroma

Immunhistochemistry of 10 traumatic human peripheral nerve neuromas and 5 normal digital nerves revealed a high immunoreactivity for the nerve growth factor (NGF) receptors p75 and trkA and the glial cell line-derived neurotrophic factor (GDNF) receptor GFRalpha-1. Semiquantitative image analysis showed a significantly increased trkA immunoreactivity in the neuroma group. The presence of the receptors may provide a way to influence therapy of peripheral nerve neuroma by administration of neurotrophins or other substances with binding sites similar to those of a neurotrophic factor.

Hyperexcitability in sensory neurons of rats selected for high versus low neuropathic pain phenotype

Selection line rats congenitally high or low for autotomy in the neuroma model of neuropathic pain (HA and LA rats) were found to be correspondingly high and low in a second type of neuropathic pain, the Chung model, which employs an alternative phenotypic endpoint, tactile allodynia. It has been proposed that both phenotypes reflect ectopic hyperexcitability in axotomized primary sensory neurons. To test this hypothesis we made in vitro recordings from sensory neurons in the L4 and 5 dorsal root ganglia. Baseline excitability was similar in HA and LA rats, and axotomy caused an increase in both lines. However, in the one neuronal subclass previously linked to neuropathic pain in these models the increase was significantly greater in HA than LA rats, and only at the time when pain scores in the two lines were diverging. Heritable differences in electrical response to axotomy in a specific afferent cell type appear to be a fundamental determinant of neuropathic pain.

Novel purinergic sensitivity develops in injured sensory axons following sciatic nerve transection in rat

Teased fibers were made from 153 spontaneous A afferents ending in sciatic nerve end neuromas of 3-14 days standing, 21 A afferents from intact sensory endings in the contralateral sciatic nerve, and 50 intact A afferents from the sciatic nerve in intact rats. Ninety-two percent of the injured fibers responded to adenosine 5'-triphosphate (ATP) (i.v.). However, few fibers from the contralateral nerve or nerves from intact animals responded to ATP. P2 receptor antagonist suramin or reactive blue 2 blocked the ATP-induced response in 76% of the fibers tested, whereas the P1 receptor antagonist aminophylline blocked the ATP-evoked effect in only 18% of the fibers tested. Sympathectomy did not affect the ATP-induced effects in injured axons. Close-arterial injection of ATP caused similar results as i.v. injection of ATP. The present study suggests that a novel purinergic sensitivity is developed at the injury site after sciatic nerve transection in rats, which may play a role in neuropathic pain under some conditions such as sympathetic activation.

Nerve growth factor inhibition prevents traumatic neuroma formation in the rat

Nerve growth factor (NGF) is thought to play a role in the pathogenesis of neuroma formation as well as in the development of neuropathic pain. In this study we attempted to antagonize NGF by using trkA-IgG, an inhibitor of NGF, consisting of the NGF receptor linked to an immunoglobulin. It was delivered by an implanted osmotic pump directly to the site of a sciatic nerve transection in 16 rats for 30 days. The animals were monitored daily for the first 2 weeks for evidence of auto-cannibalization (autotomy) of the denervated foot (a sign of neuropathic pain). Four (25%) of the 16 rats receiving trkA-IgG exhibited such cannibalization compared with 9 of 15 control rats (60%) that underwent an identical procedure but were not treated with the trkA-IgG solution. One month after surgery the sciatic nerves and representative dorsal root ganglia (DRG) from these rats were evaluated histologically. Six of the 16 experimental rats (38%) demonstrated histological evidence of neuroma formation compared with 12 of the 15 controls (80%). There were no histological differences between the DRG from the two groups. These results support the notion that inhibiting NGF following peripheral nerve injury in the rat can reduce neuroma formation and neuropathic pain without damaging the cell bodies of the transected neurons.

A comparison of the effects of lamotrigine on neuroma-induced action potential firing and normal behaviour in rat: implications for establishing a pre-clinical 'therapeutic index'

The effects of lamotrigine on rat neuroma and behavioural paradigms were evaluated to determine a pre-clinical therapeutic index. Lamotrigine blocked neuroma-induced burst pattern firing at a free plasma concentration of 13.7+/-1.7 microM (n=5). Oral dosing of lamotrigine (50-200 mg/kg) had no significant effects on behaviour but measurements of plasma concentrations of free drug showed non-linear oral absorption and lower than predicted drug levels (5-27 microM). Given intravenously (10-100 mg/kg), lamotrigine did affect behaviour at a free plasma concentration of 42.0 microM (n=2). By comparing free plasma concentrations, a therapeutic index of 3 was calculated, which is lower than published data based on comparing oral doses. We propose that a therapeutic index should only be derived with reference to plasma drug concentrations to prevent non-linear or incomplete drug absorption from confounding accurate estimation.

Comparison of autotomy behavior induced in rats by various clinically-used neurectomy methods

When a peripheral nerve is cut, a neuroma develops at its proximal end. Nerve-end neuromas are known to be a source of ectopic sensory input. In some humans this input may cause spontaneous and evoked neuropathic pain. There is currently no available animal model for developing better methods of cutting nerves that produce less painful neuromas than those currently in clinical use. Transection of the sciatic and saphenous nerves in rats also produces nerve-end neuromas. Afferent fibers in such neuromas spontaneously emit ectopic input that coincides with the outbreak of licking, scratching and self-mutilation of the denervated limb ('autotomy'). This behavior is considered to be the expression of spontaneous disagreeable sensations such as paresthesias, dysesthesias or neuropathic pain. We propose here that the autotomy model can be used as the first step for development of better neurectomy methods. As a demonstration, in this report we compared the course of autotomy expressed by rats following several methods of cutting peripheral nerves that are currently in clinical use. We found that the lowest extent of autotomy was caused by sciatic and saphenous neurectomy with a CO(2) laser. Tight ligation of the nerve, or a simple cut with scissors, also yielded significantly lower autotomy scores compared to cryoneurolysis and electrocut. The differing scores of autotomy caused by these neurectomy methods may derive from different properties of the injury discharge produced by these methods at the time of nerve cut. Our results raise the possibility that a higher incidence of neuropathic pain or related sensory disorders in humans may be expected following cryosurgical and electrocut neurectomies. If validated by further studies, neurectomy methods eliciting lower incidence of autotomy, and sensory disorders in models not based on autotomy may produce lower levels of neuropathic pain in humans.

Responses of nerve fibres of the rat saphenous nerve neuroma to mechanical and chemical stimulation: an in vitro study

The response of neuroma nerve endings to different stimuli was studied in a saphenous nerve neuroma preparation in vitro. Electrical activity was recorded from 141 single fibres dissected of saphenous nerve. One-third (27 %) displayed spontaneous activity. Based on their response to mechanical and chemical stimuli, neuroma nerve fibres were classified as mechanosensory fibres (47.5 %), mechanically insensitive chemosensory fibres (17.0 %), polymodal nociceptor fibres (28.4 %) and unresponsive fibres (7.1 %). Mechanosensory and polymodal neuroma endings responded to von Frey hair stimulation either with a few impulses (phasic units) or a sustained discharge (tonic units). Polymodal units were additionally activated by at least one of the following stimuli: acidic solutions; a combination of bradykinin, prostaglandin E2, serotonin, substance P and histamine (all at 1 microM) plus 7 mM KCl (inflammatory soup); 600 mM NaCl and capsaicin. Low pH solutions increased the firing discharge of polymodal endings proportionally to the proton concentration. The 'inflammatory soup' evoked a firing response characterized by the absence of tachyphylaxis, which appeared when its components were applied separately. Both stimuli sensitized polymodal fibres to mechanical stimulation. Hypertonic NaCl (600 mM) and capsaicin (3.3 mM) induced a prolonged discharge that outlasted the stimulus duration. Mechanically insensitive chemosensory neuroma fibres exhibited responses to chemical stimuli analogous to polymodal fibres. They became mechanically sensitive after chemical stimulation. These findings show that neuroma nerve endings in the rat saphenous nerve neuroma in vitro are functionally heterogeneous and exhibit properties reminiscent of those in intact mechanosensory, polymodal and 'silent' nociceptor sensory afferents, including their sensitization by algesic chemicals.

Pathological laughter as a presenting symptom of massive trigeminal neuromas: report of four cases

OBJECTIVE AND IMPORTANCE

This is a report of four cases of huge trigeminal neuromas that presented with the principle symptom of pathological laughter (PL).

CLINICAL PRESENTATION

All four patients were male and were in either the third or fourth decade of life. In addition to PL, there were neurological deficits related to trigeminal nerve, brainstem, and cerebellar dysfunctions.

INTERVENTION

All tumors were radically excised via a lateral basal temporal approach. The PL was cured immediately after surgery.

CONCLUSION

PL sometimes precedes other neurological manifestations and may be a useful localizing sign. The clinical and radiological features in our cases suggest that PL is a result of extra-axial compression of the pons and adjoining neural structures.

Prevention and treatment of painful neuromas of the superficial radial nerve by the end-to-side nerve repair concept: an experimental study and preliminary clinical experience

This article studies the utilization of the end-to-side neurorrhaphy concept in the prevention and treatment of painful neuromas. A total of 20 rats were divided into 2 groups (10 rats per group). In group A, the tibial nerve was divided and left lying in the subcutaneous tissue. In group B, the cut ends of the tibial nerve were sutured to the adjacent peroneal nerve in an end-to-side fashion. Evaluation was performed 90 days after nerve injury. For group A, the proximal end of the tibial nerve formed a "classic" neuroma and the distal end showed a degenerated nerve. In group B, the proximal end of the tibial nerve formed a "non-classic" neuroma and the nerve healed into the peroneal nerve with continuity of the epineurium of the 2 nerves. The distal end of the tibial nerve in group B showed evidence of axonal regeneration. Preliminary clinical experience utilizing the same technique in the prevention and treatment of painful neuromas of the superficial radial nerve is presented and other techniques of nerve-to-nerve implantation are discussed.

Role of signals from the dorsal root ganglion in neuropathic pain in a rat model

We examined whether signals from the neuroma or the dorsal root ganglion of the injured segment are critical for the generation of neuropathic pain. To this aim, we used a rat model of peripheral neuropathy made by transecting the inferior and superior caudal trunks at the level between the S1 and S2 spinal nerves under enflurane anesthesia. These animals displayed tail-withdrawal responses to normally innocuous mechanical stimulation applied to the tail with a von Frey hair (2 g). Also, these animals, compared to pre-surgical value, displayed shorter tail-withdrawal latencies following immersion of the tail to warm (40 degrees C) or cold (4 degrees C) water. Transection of the S1 spinal nerve between the dorsal root ganglion and neuroma did not change the behavioral signs of neuropathic pain. In contrast, S1 dorsal rhizotomy significantly reduced the behavioral signs. The data suggest that signals arising from the dorsal root ganglion cells of the injured segment, but not from the neuroma, are critical for the generation of neuropathic pain in this model.

Neuropathic Orofacial Pain Part 1-Prevalence And Pathophysiology

Neuropathic pain is defined as "pain initiated or caused by a primary lesion or dysfunction in the nervous system". Neuropathic orofacial pain has previously been known as "atypical odontalgia" (AO) and "phantom tooth pain". The patient afflicted with neuropathic oral/orofacial pain may present to the dentist with a persistent, severe pain, yet there are no clearly identifiable clinical or radiographic abnormalities. Accordingly, multiple endodontic procedures may be instigated to remove the likely anatomical source of the pain, yet the pain persists. There have been few studies and limited patient numbers investigating the condition. Two retrospective studies revealed the incidence of persistent pain following endodontic treatment to be 3-6% and 5% of patients; one author with wide experience in assessing the condition estimated its prevalence at 125,000 individuals in the USA alone. In one study, 50% of neuropathic orofacial pain patients reported persistent pain specifically following endodontic treatment. Patients predisposed to the condition may include those suffering from recurrent cluster or migraine headaches. Neuropathic pain states include postherpetic neuralgia (shingles) and phantom limb/stump pain. The aberrant developmental neurobiology leading to this pain state is complex. Neuropathic pain serves no protective function, in contrast to physiological pain that warns of noxious stimuli likely to result in tissue damage. The relevant clinical features of neuropathic pain include: (i) precipitating factors such as trauma or disease (infection), and often a delay in onset after initial injury (days-months), (ii) typical complaints such as dysaesthesias (abnormal unpleasant sensations), pain that may include burning, and paroxysmal, lancinating or sharp qualities, and pain in an area of sensory deficit, (iii) on physical examination there may be hyperalgesia, allodynia and sympathetic hyperfunction, and (iv) the pathophysiology includes deafferentation, nerve sprouting, neuroma formation and sympathetic efferent activity.

Interdigital neuroma: intermuscular neuroma transposition compared with resection

This prospective, randomized study compares the treatment of an interdigital neuroma (IDN) by the standard resection operation with a technique in which the IDN is transposed into the inter-muscular space between the adductor hallucis and the interossei muscles after division of the digital nerves distal to the IDN. The resection group contained 22 patients and 22 neuromas and the transposition group contained 22 patients and 23 neuromas. An interviewer, blinded as to the operative technique used, telephoned each patient preoperatively, and at 1 month, 3 months, 6 months, 12 months, and 36-48 months postoperatively. The interviewer recorded the patient's reported pain level on a numerical rating scale of 0 to 100. In the resection group the average pain level was slightly lower through the first 6 month period, but at the 12 month review the resection group had a slightly higher average pain level . At the 36-48 month survey the resection group again reported a greater average pain level and fewer asymptomatic patients. It was concluded that it is unnecessary to excise the IDN to obtain excellent relief of pain. It was also concluded that transposition of the IDN into an intermuscular position between the adductor hallucis and the interossei muscles produced significantly better long term results than did the standard resection operation.

Synaptic reorganization in the substantia gelatinosa after peripheral nerve neuroma formation: aberrant innervation of lamina II neurons by Abeta afferents

Intracellular recording and extracellular field potential (FP) recordings were obtained from spinal cord dorsal horn neurons (laminae I-IV) in a rat transverse slice preparation with attached dorsal roots. To study changes in synaptic inputs after neuroma formation, the sciatic nerve was sectioned and ligated 3 weeks before in vitro electrophysiological analysis. Horseradish peroxidase labeling of dorsal root axons indicated that Abeta fibers sprouted into laminae I-II from deeper laminae after sciatic nerve section. FP recordings from dorsal horns of normal spinal cord slices revealed long-latency synaptic responses in lamina II and short-latency responses in lamina III. The latencies of synaptic FPs recorded in lamina II of the dorsal horn after sciatic nerve section were reduced. The majority of monosynaptic EPSPs recorded with intracellular microelectrodes from lamina II neurons in control slices were elicited by high-threshold nerve stimulation, whereas the majority of monosynaptic EPSPs recorded in lamina III were elicited by low-threshold nerve stimulation. After sciatic nerve section, 31 of 57 (54%) EPSPs recorded in lamina II were elicited by low-threshold stimulation. The majority of low-threshold EPSPs in lamina II neurons after axotomy displayed properties similar to low-threshold EPSPs in lamina III of control slices. These results indicate that reoccupation of lamina II synapses by sprouting Abeta fibers normally terminating in lamina III occurs after sciatic nerve neuroma formation. Furthermore, these observations indicate that the lamina II neurons receive inappropriate sensory information from low-threshold mechanoreceptor after sciatic nerve neuroma formation.

Clinical features and outcomes in patients with non-acoustic cerebellopontine angle tumours

OBJECTIVES

Non-acoustic tumours of the cerebellopontine angle differ from vestibular schwannomas in their prevalence, clinical features, operative management, and surgical outcome. These features were studied in patients presenting to the regional neuro-otological unit.

METHODS

A retrospective analysis of clinical notes identified 42 patients with non-acoustic tumours of the cerebellopontine angle. Data were extracted regarding presenting clinical features, histopathological data after surgical resection, surgical morbidity and mortality, and clinical outcome (mean 32 months follow up).

RESULTS

The study group comprised 25 meningiomas (60%), 12 epidermoid cysts/cholesteatomata (28%), and five other tumours. In patients with meningiomas, symptoms differed considerably from patients presenting with vestibular schwannomas. Cerebellar signs were present in 52% and hearing loss in only 68%. Twenty per cent of patients had hydrocephalus at the time of diagnosis. After surgical resection, normal facial nerve function was preserved in 75% of cases. In the epidermoid group, fifth, seventh, and eighth nerve deficits were present in 42%, 33%, and 66% respectively. There were no new postoperative facial palsies. There were two recurrences (17%) requiring reoperation. Overall, there were two perioperative deaths from pneumonia and meningitis.

CONCLUSIONS

Patients with non-acoustic lesions of the cerebellopontine angle often present with different symptoms and signs from those found in patients with schwannomas. Hearing loss is less prevalent and cerebellar signs and facial paresis are more common as presenting features. Hydrocephalus is often present in patients presenting with cerebellopontine angle meningiomas. Non-acoustic tumours can usually be resected with facial nerve preservation.