Outcome of transaxillary rib resection for thoracic outlet syndrome--a 10 year experience.

BACKGROUND: This study assessed the outcome of transaxillary first and/or cervical rib resection in a unit, which has a policy of combined assessment by a neurologist and vascular surgeon. METHODS: 61 patients underwent 83 transaxillary rib resections for thoracic outlet syndrome. A retrospective case note review of these patients was undertaken. All patients completed a telephone questionnaire regarding long-term outcome. RESULTS: Post-operative outpatient assessment at a median of 6 months recorded 91.5% improved, of whom 61.5% were symptom-free. 61% were available for the telephone questionnaire at a median follow-up of 4 yr. 74% reported an improvement, with complete resolution in 58%. Six described temporary improvement following surgery. CONCLUSION: Transaxillary rib resection is a safe and effective procedure, allowing almost two thirds of patients a return to normal activity. Combined assessment by vascular and neurological teams may help in patient selection for surgery, as well as the accurate long-term assessment of outcome.

The clinical and laboratory features of chronic sensory ataxic neuropathy with anti-disialosyl IgM antibodies.

The clinical and laboratory phenotype of a paraproteinaemic neuropathy syndrome termed chronic sensory ataxic neuropathy with anti-disialosyl IgM antibodies is described in a series of 18 cases. Previous single case reports have outlined some features of this syndrome. All 18 cases were defined by the presence of serum IgM antibodies which react principally with NeuAc (alpha2-8)NeuAc(alpha2-3)Gal-configured disialosyl epitopes common to many gangliosides including GDlb, GD3, GTlb and GQlb. In 17 out of 18 cases, the serum contained benign IgM paraproteins, and in four of these cases at least two IgM paraproteins were present. The IgM antibodies were also cold agglutinins in 50% of cases. The clinical picture comprised a chronic neuropathy with marked sensory ataxia and areflexia, and with relatively preserved motor function in the limbs. In addition, 16 out of 18 cases had motor weakness affecting oculomotor and bulbar muscles as fixed or as relapsing-remitting features. When present in their entirety, these clinical features have been described previously under the acronym CANOMAD: chronic ataxic neuropathy, ophthalmoplegia, IgM paraprotein, cold agglutinins and disialosyl antibodies. This distribution of clinical features is reminiscent of Miller Fisher syndrome, in which acute-phase anti-disialylated ganglioside IgG antibodies are found. Clinical electrophysiology and nerve biopsy show both demyelinating and axonal features. A partial response to intravenous immunoglobulin and other treatments is reported in some cases.

Sural nerve fibre pathology in diabetic patients with mild neuropathy: relationship to pain, quantitative sensory testing and peripheral nerve electrophysiology.

Nerve fibre pathology is poorly described in diabetic patients with mild neuropathy and has not been adequately related to clinical evaluation, quantitative sensory examination and neurophysiology. Sural nerve myelinated and unmyelinated fibre pathology was morphometrically quantified and related to the presence of pain and conventional measures of neuropathic severity in 15 diabetic patients with mild neuropathy and 14 control subjects. Diabetic patients demonstrated a significant (P < 0.01) reduction in myelinated fibre density, but no change in fibre/axonal area, or g-ratio, compared to control subjects. Unmyelinated fibre degeneration was evidenced by an increase in the percentage of unassociated Schwann cell profiles (P < 0.0001) and a reduction in axon density (P < 0.0008) in diabetic patients. This was associated with a significant reduction in unmyelinated axon diameter (P < 0.001) with a shift of the size frequency distribution to the left (P < 0.02). Neurophysiology, quantitative sensory testing and nerve fibre pathology failed to differentiate diabetic patients with painful and painless neuropathy and failed to correlate with any measure of unmyelinated fibre pathology.

Investigation of the functional correlates of reorganization within the human somatosensory cortex.

Much work in animals and humans has demonstrated the existence of changes in topographic organization within the somatosensory cortex (SSC) after amputation or nerve injury. Afferent inputs from one area of skin are able to activate novel areas of cortex after amputation of an adjacent body part. We have investigated the functional consequences of this reorganization in a group of patients with nerve injury. Using the microneurographic technique of intraneural microstimulation (INMS) we stimulated groups of nerve fibres, within individual fascicles proximal to the nerve transection, with small electrical pulses. This enabled us to activate the deafferented cortex that had presumably undergone remodelling and study the conscious percepts described by the subjects. In 39 fascicles from 10 subjects, we found that the sensations evoked on INMS were no different from those reported previously by subjects with intact nerves. This finding suggests that such reorganization within the SSC has little effect on the function of deafferented cortical neurones or subcortical relay stations. In a separate set of experiments, INMS was performed in 16 nerve fascicles from an adjacent non-injured nerve or uninjured fascicle within a partially injured nerve. The sensations evoked by INMS in these experiments were also comparable to those obtained in normal subjects. This indicates that the expanded cortical representation of adjacent non-anaesthetic skin does not influence the cortical processing of afferent information. Taken together, these findings lead us to question the notion that reorganization of connections within the somatosensory cortex equates to a change in function. Whilst it may be advantageous that the human brain is not 'hard-wired', neurophysiological proof of functional plasticity in the adult somatosensory system as a result of deafferentation is elusive.

Superior sagittal sinus obstruction and tuberculous abscess.

Intracranial tumours such as meningiomas may occasionally produce raised intracranial pressure by occluding a venous sinus. More uncommonly, midline tumours in the occipital regions of the skull can produce elevated intracranial pressure by non-thrombotic compression of the superior sagittal sinus. We present a case of raised intracranial pressure secondary to non-thrombotic obstruction of the superior sagittal sinus by a midline tuberculous abscess.

Observations on severe ulnar neuropathy in diabetes.

We describe the clinical and neurophysiologic findings in a group of diabetic patients with a severe ulnar neuropathy. All patients attending a large inner-city diabetes center were prospectively screening for hand wasting and weakness due to ulnar nerve disease. Twenty diabetic patients fulfilling the clinical criteria underwent nerve conduction studies and electromyography. All but one patient with a motor ulnar neuropathy had systemic complications, mostly severe: ten were amputees, four had had a renal transplant, and two were blind. The onset of hand weakness was sudden in five. All patients had a classical "ulnar hand" (bilateral in five) but forearm muscles were little affected. Sensory loss was prominent in only one-half. Nerve conduction studies showed markedly reduced ulnar motor responses (mean, 1.2 mV versus 7.4 mV in controls) and ulnar/median motor ratios. Motor conduction was disproportionately slowed across the elbows, with or without conduction block, in only eight of 34 affected ulnar nerves. Five of these patients had a habit of leaning on their elbows and/or a Tinel's sign. Median sensory action potentials (SAPs) were recordable in 12 patients but ulnar SAPs were absent in 30 of 34 affected nerves. Electromyography revealed advanced denervation of ulnar supplied hand muscles. We conclude that motor ulnar neuropathy is not uncommon in patients with diabetes of long standing, especially in those with severe systemic complications. Nerve entrapment at the elbows occurs in some, but in many the lesion is axonal, and damage may occur through ischemia.

Effect of angiotensin-converting-enzyme (ACE) inhibitor trandolapril on human diabetic neuropathy: randomised double-blind controlled trial.

BACKGROUND: Diabetes is a common cause of polyneuropathy. The development and progression of nephropathy, retinopathy, and neuropathy are closely related. Angiotensin-converting enzyme (ACE) inhibitors delay progression of both nephropathy and retinopathy. We investigated the effect of ACE inhibition on diabetic neuropathy. METHODS: We recruited 41 normotensive patients with type I or type II diabetes and mild neuropathy into a randomised double-blind placebo-controlled trial. Changes in the neuropathy symptom and deficit scores, vibration-perception threshold, peripheral-nerve electrophysiology, and cardiovascular autonomic function, were assessed at 6 and 12 months. The primary endpoint was the change in peroneal nerve motor conduction velocity. FINDINGS: We found no significant difference at baseline for age, HbA1c, blood pressure, or severity of neuropathy between two groups. There was no change in HbA1c over the treatment period. Peroneal motor nerve conduction velocity (p=0.03) and M-wave amplitude (p=0.03) increased, and the F-wave latency (p=0.03) decreased and sural nerve action potential amplitude increased (p=0.04) significantly after 12 months of treatment with trandolapril compared with placebo. Vibration-perception threshold, autonomic function, and the neuropathy symptom and deficit score showed no improvement in either group. INTERPRETATION: The ACE inhibitor trandolapril may improve peripheral neuropathy in normotensive patients with diabetes. Larger clinical trials are needed to confirm these data before changes to clinical practice can be advocated.

Massive nerve root enlargement in chronic inflammatory demyelinating polyneuropathy.

OBJECTIVE: To report three patients with chronic inflammatory demyelinating polyneuropathy (CIDP) presenting with symptoms suggestive of cervical (one patient) and lumbar root disease. METHODS: Nerve conduction studies, EMG, and nerve biopsy were carried out, having found the nerve roots to be very enlarged on MRI, CT myelography, and at surgery. RESULTS: Clinically, peripheral nerve thickening was slight or absent. Subsequently one patient developed facial nerve hypertrophy. This was mistaken for an inner ear tumour and biopsied, with consequent facial palsy. Neurophysiological tests suggested a demyelinating polyneuropathy. Sural nerve biopsy showed in all cases some loss of myelinated fibres, inflammatory cell infiltration, and a few onion bulbs. Hypertrophic changes were much more prominent on posterior nerve root biopsy in one patient: many fibres were surrounded by several layers of Schwann cell cytoplasm. There was an excellent response to steroids in two patients but not in the third (most advanced) patient, who has benefited only marginally from intravenous immunoglobulin therapy. CONCLUSIONS: MRI of the cauda equina may be a useful adjunct in the diagnosis of CIDP.

Cutaneous localisation of laser induced pain in humans.

Localisation of painful laser-induced stimuli has been compared to localisation of tactile stimuli in normal humans. Laser stimulation evoked pain of two qualities (sharp pricking pain and hot burning pain). Sharp pricking pain was found to be localised with almost equal precision to tactile stimuli (13.8 +/- 3.4 versus 11.6 +/- 2.3 mm) on the dorsum of the hand, (21.5 +/- 7.9 versus 20.6 +/- 7.5 mm) on the forearm and (15.5 +/- 5.6 versus 13.8 +/- 5.4 mm) on the foot, respectively. There was no significant difference between the ability to localise tactile stimuli and hot burning pain except on the dorsum of the hand. These results indicate that tactile information is not essential for the accurate localisation of cutaneous pain.

Responsiveness of the somatosensory system after nerve injury and amputation in the human hand.

We studied the responsiveness of the somatosensory system in humans after prolonged deprivation of peripheral input. Eight patients with traumatic transection of the median or ulnar nerve and 6 patients with amputation of a finger or hand underwent microneurography and intraneural stimulation. Bundles of nerve fibers were electrically stimulated through a microelectrode placed in the affected nerve proximally to the site of damage or in the case of amputees, in a nerve fascicle supplying the stump. During intraneural stimulation the subjects with nerve injuries reported distinct percepts in the hypoesthetic skin. Their projections were usually confined to the territory of a single or two adjacent palmar digital nerves, similar to the fascicular territories of healthy nerves in control subjects, but there was much less microneurographically recordable afferent activity than in normal subjects. In amputees intraneural stimulation evoked sensations in a phantom digit or digits in over three fourths of the fascicles studied. We conclude that (1) the somatosensory system remains able to process information from a nerve fascicle that has lost its cutaneous territory, and (2) somatosensory localization remains accurate despite the presumed central reorganization that takes place after nerve division or amputation. This lack of functional adaptation has important implications with regard to our understanding of human central nervous system plasticity.

Sensory neuropathy in hereditary spastic paraplegia.

A large kinship is reported with dominantly inherited spastic paraplegia starting in the first decade of life; its clinical evolution was indistinguishable from that of "pure" hereditary spastic paraplegia (HSP). However, all patients studied had electrophysiological evidence of a predominantly sensory polyneuropathy, which was confirmed on nerve biopsy in three. The histological findings indicated virtually complete loss of large diameter fibres with relative preservation of small myelinated and non-myelinated fibres. The neuropathy was largely asymptomatic and there were no trophic ulcers. This family represents a distinct entity which differs from other reported cases of HSP with neuropathy by virtue of the clinical predominance of the pyramidal syndrome, the greater impairment of large fibre sensory modalities than of pain or temperature modalities, and the consequent absence of mutilation.

An unusual cause of postoperative brachial plexus palsy.

We describe a case of postoperative brachial plexus neurapraxia after lumbar spinal surgery performed on the prone, seated, knee-chest position. The arms were extended above the patient's head.

Increased dependence upon visual information of movement performance during visuo-motor tracking in cerebellar disorders.

The effect of temporarily suppressing the visual display of either the target (desired) trajectory or the actual movement trajectory upon the accuracy of visuo-motor tracking was studied in 6 patients with cerebellar syndromes and 6 healthy subjects. Subjects made extension and flexion movements of the wrist to superimpose a cursor displaying their actual movement (movement cursor) upon one indicating the target (target cursor) on a VDU screen. The target trajectory consisted of a sawtooth pattern of slow (4 deg/sec) ramp extension and instantaneous flexion return phases. Following practice, the tracking of cerebellar patients was significantly less accurate than that of healthy subjects for each phase (P = 0.02). Temporary suppression of the movement cursor during both the mid-section of the ramp phase (P = 0.05) and around the reversal phase (P = 0.04) caused a significant increase in tracking errors in the patients whereas suppression of the target cursor did not alter their performance. Suppression of neither cursor altered the tracking accuracy of healthy subjects during the ramp extensions whilst suppression of either caused reduced (P = 0.02) performance for the reversal phase. We interpret the increased dependence of patients upon visual information of their movements during slow trajectories as indicating an impairment of proprioceptive guidance.

The influence of external timing cues upon the rhythm of voluntary movements in Parkinson's disease.

The ability of patients with Parkinson's disease (PD) and healthy subjects to synchronise finger tapping, produced by rhythmic wrist movements, with auditory signals of target frequencies (range 1-5 Hz) and to sustain such rhythms following sudden withdrawal of auditory cues was studied. Healthy subjects were able, in the presence of auditory cues, to duplicate target frequencies accurately over the range investigated both in terms of mean tapping rate and in regularity of tapping. PD patients were less accurate under these conditions and on average tended to tap too rapidly at the lower (1-3 Hz) target frequencies and too slowly at the highest (5 Hz) target frequency. In addition, the variability of their tapping rhythms was generally greater. Healthy subjects were able to sustain tapping rhythms well following suppression of auditory signals. By contrast, withdrawal of external timing cues resulted in marked impairment of the patients' rhythm generation. At lower frequency targets (1-3 Hz) patients' tapping rates increased over rates which were already elevated in the presence of external cues. Conversely, at higher target frequencies (4-5 Hz), the average tapping rate tended to decline further from previously depressed levels. The accuracy of almost all patients fell outside the normal range. Two patterns of tapping errors were found. The first was hastening of tapping which was most evident at intermediate target frequencies. The second was faltering which occurred mainly at the higher target frequencies. These forms of behaviour may result from inherent abnormalities of internal rhythm generation since they occurred both in the presence and absence of external timing signals. Overall, our findings are consistent with the view that the basal ganglia have a role in the internal cueing of repetitive voluntary movements.

Changes in sensation after nerve injury or amputation: the role of central factors.

Dynamic changes in somatosensory cortical maps are known to occur in experimental animals subjected to peripheral nerve transection or amputation. To study the sensory effects of central nervous system adaptation to temporary or permanent loss of input from a part of the hand, multimodality quantitative sensory tests were carried out in 11 patients with complete traumatic division and repair of the median or ulnar nerves and in six patients who had undergone amputation of one or more digits. As expected, vibration, two point discrimination, and tactile thresholds were raised in the territory of the injured nerve in a graded fashion, sensitivity being poorest in the patients with the most recent injuries. Surprisingly, localisation was better in the tips than at the base of the hypoaesthetic fingers, suggesting a central attentional gradient. Stimulus-response curves conformed to a power function whose exponent was higher in denervated than in normal skin. Changes in psychophysical functions were also discernible in the intact hand. There was no hyperaesthesia in the territory of the nerve adjacent to the injured one or in the stump in the case of amputees. Central factors contribute to the sensory changes seen after nerve injury, but the functional effects of the cortical reorganisation that follows partial deafferentation are more subtle than a simple heightening of sensitivity in the surrounding skin.

Favourable outcome in non-traumatic anterior interosseous nerve lesions.

Six patients with non-traumatic anterior interosseous nerve palsy are described. In five patients the onset was acute with upper arm pain, which peaked within 4 weeks and thereafter declined. Virtually complete spontaneous recovery occurred in all patients between 9 and 24 months. It is concluded that non-traumatic anterior interosseous nerve lesions are most likely to reflect a circumscribed form of brachial neuritis and that surgical decompression should be deferred for at least a year or indefinitely if recovery is proceeding.

Endoneurial capillary abnormalities in mild human diabetic neuropathy.

Microvascular factors have been implicated in the pathogenesis of human diabetic neuropathy. The extent of microangiopathy was assessed in 15 diabetic patients with clinically mild neuropathy and compared with eight age matched control subjects. Endoneurial capillary density was reduced (p less than 0.04) and correlated significantly with reduced myelinated fibre density (p less than 0.01). Both basement membrane area (p less than 0.0001) and endothelial cell profile number per capillary (p less than 0.002) were significantly increased in diabetic patients and correlated significantly with both neurophysiological and neuropathological measures of neuropathic severity. There was no evidence of endothelial cell hypertrophy as assessed by either cross sectional endothelial cell area or a reduction in luminal size. Furthermore, the percentage of closed vessels did not differ between diabetic patients and control subjects and failed to relate to measures of neuropathic severity. It was concluded that microvascular abnormalities are prominent in patients with clinically mild human diabetic neuropathy, and that these data provide further support for the role of endoneurial capillary disease in the development of this condition.

On the choice of muscle in the electrophysiological assessment of myasthenia gravis.

We performed repetitive nerve stimulation on 38 adult patients with generalised myasthenia to compare the relative diagnostic yield from deltoid and trapezius. The decrement was consistently greater in deltoid, both before and after maximum voluntary contraction. In 12 patients the test was negative in trapezius but diagnostic in deltoid, whereas the converse occurred in only one. The yield from facial muscles was comparable to that from trapezius while that from hand muscles was very low. Post-tetanic exhaustion often enhanced the decrement but the use of stimulus frequencies greater than 2-3 Hz did not. We conclude that deltoid provides the highest diagnostic yield in myasthenia when doing decremental studies.