Supinator to Posterior Interosseous Nerve Transfer for Recovery of Hand Opening in the Tetraplegic Patient: A Case Series

BACKGROUND AND OBJECTIVES

Cervical spinal cord injury results in devastating loss of function. Nerve transfers can restore functional use of the hand, the highest priority function in this population to gain independence. Transfer of radial nerve branches innervating the supinator to the posterior interosseous nerve (SUP-PIN) has become a primary intervention for the recovery of hand opening, but few outcome reports exist to date. We report single-surgeon outcomes for this procedure.

METHODS

The SUP-PIN transfer was performed on adults with traumatic spinal cord injury resulting in hand paralysis. Outcome measures include Medical Research Council strength grade for extension of each digit, and angles representing critical apertures: the first web space opening of the thumb, and metacarpophalangeal angle of the remaining fingers. Factors affecting these measurements, including preserved tone and spasticity of related muscles, were also assessed.

RESULTS

Twenty-three adult patients with a C5-7 motor level underwent SUP-PIN transfers on 36 limbs (median age 31 years, interquartile range [21.5, 41]). The median interval from injury to surgery was 10.5 (8.2, 6.5) months, with 9 (7.5, 11) months for the acute injuries and 50 (32, 66) months for the chronic (>18 months) injuries. Outcomes were observed at a mean follow-up of 22 (14, 32.5) months. 30 (83.3%) hands recovered at least antigravity extension of the thumb and 34 (94.4%) demonstrated successful antigravity strength for the finger extensors, providing adequate opening for a functional grasp. Chronic patients (>18 months after injury) showed similar outcomes to those who had earlier surgery. Supination remained strong (at least M4) in all but a single patient and no complications were observed.

CONCLUSION

SUP-PIN is a reliable procedure for recovery of finger extension. Chronic patients remain good candidates, provided innervation of target muscles is preserved. Higher C5 injuries were more likely to have poor outcomes.

Axillary to Radial Nerve Transfer for Recovery of Elbow Extension After Spinal Cord Injury

BACKGROUND AND OBJECTIVES

Cervical spinal cord injuries (SCI) result in severe loss of function and independence. Nerve transfers have become a powerful method for restoring upper extremity function, the most critical missing function desired by this patient population. Recovery of active elbow extension allows for expansion of one's workspace to reach for objects and stabilizes control at the elbow joint. Without triceps function, a patient with a cervical SCI is rendered entirely helpless when in the supine position. Our objective was to provide a concise description of the transfer of branches of the axillary nerve (AN) to the long head of the triceps branch of the radial nerve (RN) for restoration of elbow extension after cervical SCI.

METHODS

An anterior, axillary approach is used for the transfer of the nerve branches of the AN (which may include branches to the teres minor, posterior deltoid, or even middle deltoid) to the long head of the triceps branch of the RN. Preoperative assessment and intraoperative stimulation are demonstrated to direct optimal selection of axillary branch donors.

RESULTS

The axillary approach provides full access to all branches of the AN in optimal proximity to triceps branches of the RN and allows for tension-free coaptation to achieve successful recovery of elbow extension. Final outcomes may not be achieved for 18 months. Of our last 20 patients with greater than 12-month follow-up, 13 have achieved antigravity strength in elbow extension, 4 are demonstrating ongoing progression, and 3 are definitive failures by 18 months.

CONCLUSION

The axillary to RN transfer is an important intervention for recovery of elbow extension after cervical SCI, which significantly improves quality of life in this patient population. Further large population outcomes studies are necessary to further establish efficacy and increase awareness of these procedures.

Selective Tibial Neurotomy for Spastic Equinovarus Foot: Operative Technique

BACKGROUND AND OBJECTIVES

Spastic equinovarus foot (SEF) is a common complication of stroke and other upper motor neuron injuries. It is characterized by a plantigrade and inverted foot, often with toe curling, causing significant disability from pain, gait, and balance difficulties. Management includes physical therapy, antispasticity drugs, orthoses, chemical neurolysis, or botulinum toxin, all of which may be insufficient, sedating, or transient. Selective tibial neurotomy (STN) provides a surgical option that is effective and long-lasting. Our goal is to provide a concise description of our technique for performing the STN for treatment of SEF. We discuss the standard posterior approach with surgical variations used by other groups and a medial approach, should the posterior approach be insufficient.

METHODS

A posterior leg approach allows access to the tibial nerve and its branches to the bilateral gastrocnemius muscles, soleus, posterior tibialis, and extrinsic toe flexors. A medial approach is used if the toe flexors cannot be accessed sufficiently from the posterior approach. Nerve branch targets identified by preoperative functional assessment are carefully exposed and fully neurolysed distally to identify all terminal branches to each muscle of interest before neurotomy.

RESULTS

The STN is a powerful tool for treating SEF, with an immediate and lasting effect. Approximately 80% of the target muscle should be denervated to ensure long-term efficacy while maintaining adequate function of the muscle through collateral innervation.

CONCLUSION

The STN is a safe and effective outpatient procedure that can be performed by an experienced nerve surgeon to improve balance and ambulation and reduce pain for patients with SEF. Large clinical trials are necessary to further establish this underutilized procedure in the United States.

Restoring bladder function using motor and sensory nerve transfers: a cadaveric feasibility study

OBJECTIVE

Bladder dysfunction after nerve injury has a variable presentation, and extent of injury determines whether the bladder is spastic or atonic. The authors have proposed a series of 3 nerve transfers for functional innervation of the detrusor muscle and external urethral sphincter, along with sensory innervation to the genital dermatome. These transfers are applicable to only cases with low spinal segment injuries (sacral nerve root function is lost) and largely preserved lumbar function. Transfer of the posterior branch of the obturator nerve to the vesical branch of the pelvic nerve provides a feasible mechanism for patients to initiate detrusor contraction by thigh adduction. External urethra innervation (motor and sensory) may be accomplished by transfer of the vastus medialis nerve to the pudendal nerve. The sensory component of the pudendal nerve to the genitalia may be further enhanced by transfer of the saphenous nerve (sensory) to the pudendal nerve. The main limitations of coapting the nerve donors to their intrapelvic targets are the bifurcation or arborization points of the parent nerve. To ensure that the donor nerves had sufficient length and diameter, the authors sought to measure these parameters.

METHODS

Twenty-six pelvic and anterior thigh regions were dissected in 13 female cadavers. After the graft and donor sites were clearly exposed and the branches identified, the donor nerves were cut at suitable distal sites and then moved into the pelvis for tensionless anastomosis. Diameters were measured with calipers.

RESULTS

The obturator nerve was bifurcated a mean ± SD (range) of 5.5 ± 1.7 (2.0-9.0) cm proximal to the entrance of the obturator foramen. In every cadaver, the authors were able to bring the posterior division of the obturator nerve to the vesical branch of the pelvic nerve (located internal to the ischial spine) in a tensionless manner with an excess obturator nerve length of 2.0 ± 1.2 (0.0-5.0) cm. The distance between the femoral nerve arborization and the anterior superior iliac spine was 9.3 ± 1.8 (6.5-15.0) cm, and the distance from the femoral arborization to the ischial spine was 12.9 ± 1.4 (10.0-16.0) cm. Diameters were similar between donor and recipient nerves.

CONCLUSIONS

The chosen donor nerves were long enough and of sufficient caliber for the proposed nerve transfers and tensionless anastomosis.

Spinal motor neuron transplantation to enhance nerve reconstruction strategies: Towards a cell therapy

Nerve transfers have become a powerful intervention to restore function following devastating paralyzing injuries. A major limitation to peripheral nerve repair and reconstructive strategies is the progressive, fibrotic degeneration of the distal nerve and denervated muscle, eventually precluding recovery of these targets and thus defining a time window within which reinnervation must occur. One proven strategy in the clinic has been the sacrifice and transfer of an adjacent distal motor nerve to provide axons to occupy, and thus preserve (or "babysit"), the target muscle. However, available nearby nerves are limited in severe brachial plexus or spinal cord injury. An alternative and novel proposition is the transplantation of spinal motor neurons (SMNs) derived from human induced pluripotent stem cells (iPSCs) into the target nerve to extend their axons to occupy and preserve the targets. These cells could potentially be delivered through minimally invasive or percutaneous techniques. Several reports have demonstrated survival, functional innervation, and muscular preservation following transplantation of SMNs into rodent nerves. Advances in the generation, culture, and differentiation of human iPSCs now offer the possibility for an unlimited supply of clinical grade SMNs. This review will discuss the previous reports of peripheral SMN transplantation, outline key considerations, and propose next steps towards advancing this approach to clinic. Stem cells have garnered great enthusiasm for their potential to revolutionize medicine. However, this excitement has often led to premature clinical studies with ill-defined cell products and mechanisms of action, particularly in spinal cord injury. We believe the peripheral transplantation of a defined SMN population to address neuromuscular degeneration will be transformative in augmenting current reconstructive strategies. By thus removing the current barriers of time and distance, this strategy would dramatically enhance the potential for reconstruction and functional recovery in otherwise hopeless paralyzing injuries. Furthermore, this strategy may be used as a permanent axon replacement following destruction of lower motor neurons and would enable exogenous stimulation options, such as pacing of transplanted SMN axons in the phrenic nerve to avoid mechanical ventilation in high cervical cord injury or amyotrophic lateral sclerosis.

Supinator to Posterior Interosseous Nerve Transfer for Restoration of Finger Extension

BACKGROUND

Cervical spinal cord injuries result in a severe loss of function and independence. The primary goal for these patients is the restoration of hand function. Nerve transfers have recently become a powerful intervention to restore the ability to grasp and release objects. The supinator muscle, although a suboptimal tendon transfer donor, serves as an ideal distal nerve donor for reconstructive strategies of the hand. This transfer is also applicable to lower brachial plexus injuries.

OBJECTIVE

To describe the supinator to posterior interosseous nerve transfer with the goal of restoring finger extension following spinal cord or lower brachial plexus injury.

METHODS

Nerve branches to the supinator muscle are transferred to the posterior interosseous nerve supplying the finger extensor muscles in the forearm.

RESULTS

The supinator to posterior interosseous nerve transfer is effective in restoring finger extension following spinal cord or lower brachial plexus injury.

CONCLUSION

This procedure represents an optimal nerve transfer as the donor nerve is adjacent to the target nerve and its associated muscles. The supinator muscle is innervated by the C5-6 nerve roots and is often available in cases of cervical SCI and injuries of the lower brachial plexus. Additionally, supination function is retained by supination action of the biceps muscle.

Risk factors for pneumonia in the elderly

PURPOSE

To investigate the prevalence of certain chronic conditions among the elderly and to estimate the relative risk for pneumonia associated with each condition.

PATIENTS AND METHODS

Medical records of all inhabitants aged 60 years or more (4,175 persons) in one township (population 24,716) in Finland were reviewed, seeking 15 chronic conditions. Which patients had pneumonia in the same population was prospectively ascertained over a period of 3 years (185 patients).

RESULTS

Hypertension was the most frequent chronic condition (36.4%) in the study population. Other common conditions were heart disease (23.7%, with chronic compensated heart failure in 96.3% of these), other cardiovascular disease (13.1%), and diabetes (13.1%). The prevalence of any other condition was less than 5%. The following conditions were significantly more common among pneumonia patients than among control subjects: heart disease (38.4% versus 23.0%), lung disease (13.0% versus 3.8%), bronchial asthma (11.9% versus 3.1%), immunosuppressive therapy (2.7% versus 0.8%), alcoholism (2.2% versus 0.3%), and institutionalization (8.6% versus 3.9%). By multivariate logistic regression analysis, independent risk factors for pneumonia were alcoholism (relative risk [RR] = 9.0, confidence interval [CI] = 5.1 to 16.2), bronchial asthma (RR = 4.2, CI = 3.3 to 5.4), immunosuppressive therapy (RR = 3.1, CI = 1.9 to 5.1), lung disease (RR = 3.0, CI = 2.3 to 3.9), heart disease (RR = 1.9, CI = 1.7 to 2.3), institutionalization (RR = 1.8, CI = 1.4 to 2.4), and age (70 years or more versus 60 to 69 years; RR = 1.5, CI = 1.3 to 1.7). One third of the study population and 57% of the pneumonia patients had one or more of these risk factors. Diabetes, chronic pyelonephritis, and malignancies of sites other than the lungs were not associated with increased risk for pneumonia.

CONCLUSION

We found which elderly persons have an increased risk for pneumonia. Although the highest relative risk was associated with alcoholism, that condition was rare in this elderly population. Chronic obstructive lung diseases were more common and were also associated with a high relative risk. Heart disease had the highest public health impact because it was very common among the elderly and increased the risk of contracting pneumonia almost twofold; it also increased the risk of pneumonia-related death. These population-based data confirm and extend previous findings derived from selected patient groups and are useful for designing cost-effective pneumonia prevention programs.

The effect of gossypol on the frequency of DNA-strand breaks in human leukocytes in vitro

Gossypol, a human antifertility agent isolated from the cotton plant, was found to induce a dose-dependent increase in the frequency of DNA-strand breaks in human leukocytes exposed to 2-40 micrograms/ml of the drug for 1 h in serum-free medium in vitro. DNA-strand breaks were studied by alkaline elution or alkaline unwinding of DNA followed by hydroxylapatite-chromatography. No decrease of gossypol-induced DNA-strand breaks was observed after post-treatment incubation times up to 24 h, whereas X-ray-induced DNA breaks disappeared within 2 h under the same incubation conditions. Cells exposed to gossypol in the presence of 10% fetal calf serum showed no or little increase of DNA breaks, suggesting that serum proteins inhibit the DNA-damaging activity of the drug. Both optical isomers of gossypol induced DNA-strand breaks. However, the effect of (-)-gossypol was only about half of that of (+)-gossypol and the racemic form. The induction and persistence of DNA-strand breaks by gossypol, as well as the reduction of this effect in the presence of serum should be considered in the evaluation of the potential in vivo genotoxicity of the drug.

DNA cross-links in human leucocytes treated with vinyl acetate and acetaldehyde in vitro

Human leucocytes were incubated in the presence of vinyl acetate or acetaldehyde (10-20 mM) for 4 h at 37 degrees C in vitro. DNA damage was analysed by alkaline elution. None of the compounds induced a detectable increase in the frequency of DNA strand breaks. Cells exposed to 5 Gy of X-ray immediately after treatment and before alkaline elution showed a clear, dose-dependent retardation of the elution rate in comparison with X-irradiated control cells. These results demonstrate that both vinyl acetate and acetaldehyde induce DNA cross-links in human cells.

Different SCE-inducing effects of HN2 and MMS in early and late G1 in human lymphocytes

The induction of SCE was studied in PHA-stimulated human lymphocytes exposed to nitrogen mustard (HN2) or methyl methanesulfonate (MMS) for various time periods in the G1 phase. HN2 was found to induce about 10 times more SCE when cells were exposed in late G1 (24 h after PHA) as compared to early G1 (immediately after PHA). In contrast, only a small difference was observed between cells exposed to MMS in late or early G1. The results suggest that different types of SCE-inducing alkylating damage agents are removed at widely different rates in human G1-lymphocytes.

Removal and persistence of SCE-inducing damage in human lymphocytes in vitro

The SCE frequency was studied in PHA-stimulated human lymphocytes exposed to various SCE-inducing agents in different stages of the cell cycle. Melphalan, HN2, MMS, and UV light were found to induce a higher SCE frequency in late G1 (18-24 hr after PHA stimulation) than in early G1 (1-6 hr after PHA) or G0 (before PHA stimulation). In contrast, CCNU induced more SCEs in early G1 than in late G1, and the adriamycin-induced SCE frequency was about the same after treatment in early and late G1. These results suggest that SCE-inducing lesions are being removed at different rates in human G1 lymphocytes. The removal of SCE-inducing HN2 lesions was found to be about 10 times more rapid in late G1 than in early G1, indicating the activation of a cross-link repair mechanism prior to DNA replication in human lymphocytes. Cells treated with MMS in the second G1 (after cultivation for about 55 hr in the presence of PHA and BrdUrd) showed a higher SCE frequency than cells treated with the same dose of MMS in the first G1. This result indicates that some type of interaction occurs between MMS damage and BrdUrd lesions in the DNA during replication, which leads to an enhanced induction of SCE. Analysis of SCEs induced during the 2 first vs. the third cell cycle in third-generation metaphases showed that most of the SCE-inducing damage caused by treatment with HN2 and melphalan in G1 of the first cell cycle are removed before the S phase of the third cell cycle, whereas damage caused by MMS and adriamycin seem to be more persistent. These observations suggest that the rate by which different types of SCE-inducing damage are removed or modified in resting (G0) of PHA-stimulated human lymphocytes can have a great influence on the SCE frequency. This is of practical importance in studies using SCE analysis to evaluate human exposure to suspected genotoxic agents in the environment.

DNA repair replication, DNA breaks and sister-chromatid exchange in human cells treated with adriamycin in vitro

The effects of adriamycin (AM) on DNA repair replication, the frequency of sister-chromatid exchange (SCE), the rate of cell proliferation and the frequency of DNA strand breaks were studied in human cells in vitro. No repair replication was observed in lymphocytes exposed to AM in concentrations up to 10(-3) moles/l. DNA repair replication induced by UV and alkylating agents was not affected by a concentration of AM that completely inhibited cell proliferation (10(-6) moles/l). Fibroblasts exposed to AM at 10(-4) moles/l in the presence of hydroxyurea showed an increase of strand breaks and cross-links in DNA. When AM was added to UV-irradiated fibroblasts, there was an increase of DNA strand breaks in addition to the breaks caused by UV alone. Similar effects were observed in lymphocytes. A dose-dependent increase of SCE was observed in lymphocytes exposed to low concentrations of AM (less than 10(-7) moles/l). At higher concentrations the increase of SCE levelled off, and cell proliferation became severely inhibited. There was no evidence of removal of SCE-inducing damage in cells exposed to AM during G0 or G1. The level of SCE induced in the third cell cycle after treatment with AM was not different from that induced during the first two cell cycles. These results suggest that the various genotoxic and cytotoxic effects of AM are caused by different types of cellular damage. Moreover, AM-induced DNA damage persists for several cell cycles in human cells in vitro and seems to be resistant to repair activity.

Sister chromatid exchange in human populations: the effect of smoking, drug treatment, and occupational exposure

Increased rate of sister chromatid exchange (SCE) in peripheral lymphocytes has been observed in smokers as compared to nonsmokers and in patients receiving certain cytostatic drugs. The increased SCE frequency in smokers was shown to depend on the number of cigarettes smoked per day, as well as on the duration of smoking. DNA cross-links caused by photochemotherapy against psoriasis, 8-methoxypsoralen plus UVA irradiation (PUVA), as well as by the anti-cancer chemotherapeutic agent CCNU, were shown to be more effective at inducing SCE's than other types of DNA damage caused by these treatments. These observations suggest that SCE analysis may be used as an indicator of genotoxic exposure in vivo, provided that the various types of DNA damage caused by genotoxic agents and the dose, as well as the time of exposure in relation to the time of sampling, are considered.

Characterization of cell lines derived from hamster tumors induced with the BK virus

Some of the properties of three continuous cell lines derived from BK virus-induced hamster tumors were examined. The cell lines had in vitro growth characteristics of transformed cells. Morphologically most of the cells were fibroblastic, but multinucleated giant cells were also common. Ultrastructurally all three cell lines displayed the usual features of cells grown in vitro. Marked variation in the nuclear size and shape as well as prominent nucleoli were characteristic to these cells. No viruses or virus-like particles were found. Virus isolation attempts by fusing the cells with Vero cells were negative, and no virion antigen was detected in these cells by immunofluorescence. T antigen similar to that of other papovaviruses was found in the cells. This antigen stained with sera from a number of hamsters carrying transplanted BK virus-induced tumors, and also with SV 40 T antisera. The antigen disappeared after 30 minutes at 56 degrees C. Cytogenetic analyses showed that the three cell lines were heteroploid with subtetraploid numbers of chromosomes. Chromosome abnormalities were also seen. All three cell lines induced sarcomatous tumors in adult hamsters after subcutaneous inoculation.