Ralph T. W. M. Thomeer

Natural history of obstetric brachial plexus palsy: a systematic review

Obstetric brachial plexus palsy (OBPP) is caused by traction to the brachial plexus during labour.1,2 In the majority of cases delivery of the upper shoulder is blocked by the mother’s pubic symphysis (shoulder dystocia). If additional traction is applied to the child’s head, the angle between the neck and the shoulder is forcefully widened, overstretching the ipsilateral brachial plexus. The resulting traction injury may vary from neurapraxia or axonotmesis to neurotmesis and avulsion of rootlets from the spinal cord. Recently, the exact origin of OBPP was again a matter of debate.3 It was suggested that intrauterine maladaptation, not nerve traction, causes the plexopathy. The incidence of OBPP varies from 1.6 to 2.9 per 1000 births in prospective studies.4,5 The upper brachial plexus is most commonly affected, resulting in paresis of the shoulder and biceps muscles, as first described by Erb and Duchenne.6 Hand function is additionally impaired in approximately 15% of patients;4,7,8 isolated injury to the lower plexus (Déjèrine-Klumpke’s type) is rare.9 The extent of neural damage can only be assessed by evaluating recovery in the course of time because nerve lesions of different severity initially present with the same clinical features. Neurapraxia and axonotmesis eventually result in complete recovery. Neurotmesis and root avulsion, on the other hand, result in permanent loss of arm function, which may lead in time to the development of skeletal malformations, cosmetic deformities, behavioural problems, and socioeconomic limitations.10–14 At present, most authors advise surgical exploration of the brachial plexus if spontaneous recovery is considered insufficient at a preset age.15–17 Absence of biceps function at 3 months of age is regarded as the key indicator for surgical exploration by some authors.15,18 Others use a combined score of different movements to decide whether nerve surgery should be performed at 9 months.16 Ancillary testing, in particular electromyography, is not considered reliable enough for prognostication.19,20 Methods of repair include nerve grafting after resection of the neuroma and nerve transfer in the case of root avulsion.15,21–25 Results achieved by these surgical approaches are claimed to be superior to the outcome in conservatively treated patients with equally severe lesions.15,26–28 However, this comparison relies on historical controls;29 no randomized study has been performed.6,30 In this context, the true percentage of infants who do not recover from OBPP becomes important as these children might benefit from reconstructive surgery. Reliable data on the frequency and severity of functional deficits in the natural course of OBPP are a prerequisite for developing adequate treatment strategies. Furthermore, such data would provide parents of newborn infants with OBPP with realistic information on prognosis. The prognosis of OPBB is generally considered to be very good, with complete or almost complete spontaneous recovery in over 90% of patients.25,31–35 However, this view is based on a limited number of studies37 which are cited indiscriminately without considering the methodology used. In the present review we performed a systematic literature search38 to clarify the natural course of untreated OBPP. Ideally, a study on the natural course of OBPP should be a prospective analysis of a demographic population with sufficient followup and clear end-stage assessment. We applied four predefined criteria to assess the methodological quality of the available studies: study-design, population, duration of follow-up, and assessment of end-stage.39

Prolonged conservative care versus early surgery in patients with sciatica caused by lumbar disc herniation: two year results of a randomised controlled trial.

Objectives To evaluate the effects of early lumbar disc surgery compared with prolonged conservative care for patients with sciatica over two years of follow-up. Design Randomised controlled trial. Setting Nine Dutch hospitals. Participants 283 patients with 6-12 weeks of sciatica. Interventions Early surgery or an intended six months of continued conservative treatment, with delayed surgery if needed. Main outcome measures Scores from Roland disability questionnaire for sciatica, visual analogue scale for leg pain, and Likert self rating scale of global perceived recovery. Results Of the 141 patients assigned to undergo early surgery, 125 (89%) underwent microdiscectomy. Of the 142 patients assigned to conservative treatment, 62 (44%) eventually required surgery, seven doing so in the second year of follow-up. There was no significant overall difference between treatment arms in disability scores during the first two years (P=0.25). Improvement in leg pain was faster for patients randomised to early surgery, with a significant difference between “areas under the curves” over two years (P=0.05). This short term benefit of early surgery was no longer significant by six months and continued to narrow between six months and 24 months. Patient satisfaction decreased slightly between one and two years for both groups. At two years 20% of all patients reported an unsatisfactory outcome. Conclusions Early surgery achieved more rapid relief of sciatica than conservative care, but outcomes were similar by one year and these did not change during the second year. Trial Registry ISRCT No 26872154.

Cortical Excitability of the Biceps Muscle after Intercostal-to-Musculocutaneous Nerve Transfer

OBJECTIVE Restoration of volitional control over elbow flexion has been demonstrated in patients who have undergone intercostal-to-musculocutaneous nerve transfer. We investigated the cortical area involved in the control over elbow flexion after intercostal-to-musculocutaneous nerve transfer. METHODS Maps of magnetically excitable cortical areas of the affected arms of five patients were compared with maps of their healthy arms and maps of both arms of four healthy control subjects. The intercostal cortical area was also studied, requiring needle electromyography mapping (n = 1). RESULTS The cortical areas of affected arms were smaller and less excitable than those of healthy arms. The locations of these areas could not be distinguished from that of the normal cortical biceps area but seemed to differ from that of the intercostal cortical area. CONCLUSION The existence of a biceps-like cortical area related to the reinnervated muscle can be explained in two ways. Interneurons from the original biceps area might excite the cortical neurons controlling the intercostal muscles. Alternatively, corticospinal neurons of the original biceps area may project directly onto spinal intercostal motor neurons. Cerebral plasticity does occur in intercostal-to-musculocutaneous nerve transfers and may be crucial for their clinical success.

Management of sciatica due to lumbar disc herniation in the Netherlands: a survey among spine surgeons

OBJECT Although clinical guidelines for sciatica have been developed, various aspects of lumbar disc herniation remain unclear, and daily clinical practice may vary. The authors conducted a descriptive survey among spine surgeons in the Netherlands to obtain an overview of routine management of lumbar disc herniation. METHODS One hundred thirty-one spine surgeons were sent a questionnaire regarding various aspects of different surgical procedures. Eighty-six (70%) of the 122 who performed lumbar disc surgery provided usable questionnaires. RESULTS Unilateral transflaval discectomy was the most frequently performed procedure and was expected to be the most effective, whereas percutaneous laser disc decompression was expected to be the least effective. Bilateral discectomy was expected to be associated with the most postoperative low-back pain. Recurrent disc herniation was expected to be lowest after bilateral discectomy and highest after percutaneous laser disc decompression. Complications were expected to be highest after bilateral discectomy and lowest after unilateral transflaval discectomy. Nearly half of the surgeons preferentially treated patients with 8-12 weeks of disabling leg pain. Some consensus was shown on acute surgery in patients with short-lasting drop foot and those with a cauda equina syndrome, and nonsurgical treatment in patients with long-lasting, painless drop foot. Most respondents allowed postoperative mobilization within 24 hours but advised their patients not to resume work until 8-12 weeks postoperatively. CONCLUSIONS Unilateral transflaval discectomy was the most frequently performed procedure. Minimally invasive techniques were expected to be less effective, with higher recurrence rates but less postoperative low-back pain. Variety was shown between surgeons in the management of patients with neurological deficit. Most responding surgeons allowed early mobilization but appeared to give conservative advice in resumption of work.

Electrophysiology and morphometry of the Aα- and Aβ-fiber populations in the normal and regenerating rat sciatic nerve

We studied electrophysiological and morphological properties of the Aa- and Ah-fibers in the regenerating sciatic nerve to establish whether these fiber types regenerate in numerical proportion and whether and how the electrophysiological properties of these fiber types are adjusted during regeneration. Compound action potentials were evoked from isolated sciatic nerves 12 weeks after autografting. Nerve fibers were gradually recruited either by increasing the stimulus voltage from subthreshold to supramaximal levels or by increasing the interval between two supramaximal stimuli to obtain the cumulative distribution of the extracellular firing thresholds and refractory periods, respectively. Thus, the mean conduction velocity (MCV), the maximal charge displaced during the compound action potential (Qmax), the mean firing threshold (V50), and the mean refractory period (t50) were determined. The number of myelinated nerve fibers and their fiber diameter frequency distributions were determined in the peroneal nerve. Mathematical modeling applied to fiber recruitment and diameter distributions allowed discrimination of the Aa- and Ah-fiber populations. In regenerating nerves, the number of Aa-fibers increased fourfold while the number of Ah-fibers did not change. In regenerating Aa- and Ah-fibers, the fiber diameter decreased and V50 and t50 increased. The regenerating Aa-fibers’ contribution to Qmax decreased considerably while that of the Ah-fibers remained the same. Correlation of the electrophysiological data to the morphological data provided indications that the ion channel composition of both the Aa- and Ah-fibers are altered during regeneration. This demonstrates that combining morphometric and electrophysiological analysis provides better insight in the changes that occur during regeneration.

Reimplantation of ventral rootlets into the cervical spinal cord after their avulsion: an anterior surgical approach

Root avulsions from the cervical spinal cord due to traction injuries are beyond repair up to the present day. An anterior surgical approach has been developed in cats for reimplantation of the ventral rootlets into the site of avulsion. The consecutive surgical steps towards exposure of the ventral surface of the cervical cord are given in detail. The morphological relations during the operative procedure are explained in the text and by illustrations. In this study the surgery related mortality rate was 16% and the overall mortality rate amounted to 21%. Loss of blood, initially a major problem, was coped with by increasing technical experience and the infusion of plasma expanding fluid. In 2 animals with survival times of 209 and 293 days respectively, many ventral horn motoneurons were found HRP-positive after retrograde HRP transport through the site of reimplantation. The findings provide evidence that the axonal continuity between reimplanted ventral roots and their motoneurons may be restored.

Respiration-related activity in the biceps brachii muscle after intercostal-musculocutaneous nerve transfer

Needle EMG and polygraphic recordings of respiration and biceps activity were obtained in 7 patients who had undergone intercostal to musculocutaneous nerve transfer because of severe traumatic injury to the brachial plexus. EMG activity during expiration and inspiration was assessed during quiet breathing, deep breathing, and during sustained inspiration and expiration, and compared to the clinical strength of the biceps muscle. Biceps activity was consistently found during both expiration and inspiration, and in either case separately related to the flexion force levels. Initially this relationship appeared equally strong for both phases. With time, control over flexion changes from a completely respiratory-driven control to a conscious volitional control; however, involuntary effects of respiration always remained present in polygraphic recordings. Theoretical explanations for the change in control are put forward.

Nerve grafting from spinal cord to spinal nerve: a microsurgical technique in cats

A ventral surgical approach is described for the grafting of autologous saphenous nerves between the spinal cord and the avulsed C7 ventral root in the cat. To overcome serious blood loss from the epidural venous plexus, the cats were hyperventilated (end tidal PCO2 to about 23 mmHg) and controlled hypotension was induced (mean arterial pressure to about 60 mmHg). After selective avulsion of the ventral rootlets C7 the saphenous grafts were implanted into the spinal cord and coaptated to the avulsed spinal nerve. The combination of advanced anesthetic methods and microsurgical techniques appeared to be mandatory to achieve a low surgical mortality. Regenerated axons were retrogradely traced using retrograde horseradish peroxidase (HRP), and their functional recovery was evaluated by means of electrophysiological methods.

The dorsoscapular nerve in traumatic brachial plexus lesions

The origin and course of the nerval innervation of the levator scapulae and rhomboid muscles was studied in four human cadavers. Special attention was given to surgical anatomy. The levator scapulae muscle receives two small segmental nerves from C3 and C4, respectively. The rhomboid muscle receives two segmental nerves, one from C4 and the other from C5. Moreover, in a series of 137 patients with a traumatic brachial plexus lesion, the linkage between levator scapulae and rhomboid muscle function impairment and site of the brachial plexus lesion was studied. Paresis of one or both of these muscles was noted in 13 cases. It was concluded that the rhomboid muscle may function on a single C4 nerve supply without any loss of strength. Arguments are put forward to support the relevance of rhomboid muscle testing in the assessment of brachial plexus lesions.

Ultrastructural study on avulsion effects of the cat cervical moto-axonal pathways in the spinal cord

After selective avulsion of the ventral root cervical 7 (C7) from the adult cat spinal cord, the intraspinal trajectories of the torn axons in the white matter were studied at different survival times. Two phases could be discerned: an early phase which showed changes that occurred up to 14 days after avulsion and a second phase from day 30 onwards. Two days postoperatively, considerably swollen, empty myelin sheaths occurred, which remained present up to 14 days after avulsion. A primary increase in the number of glial cells (microglia) was noted on days 2 and 4 after avulsion. Ultrastructurally, unmyelinated and myelinated terminal clubs were found 8 and 14 days after avulsion. These clubs were characterized as cones of growth, related to axonal regeneration. A second glial increase was present after 30 days. At that time, the entire moto-axonal pathway clearly showed a degeneration pattern. This finding was light microscopically confirmed by an increase of GFAP-positive astrocytes. During the first 30 days, a front of small calibre myelinated axons, starting at the transition zone of the grey and white matter traversed halfway through the moto-axonal pathway. However, on days 60 and 90 no further shift of the front had occurred.