Posterior spinal fusion to sacrum in non-ambulatory hypotonic neuromuscular patients: sacral rod/bone graft onlay method

Purpose

A retrospective study involving 65 non-ambulatory patients with hypotonic neuromuscular scoliosis has assessed the effectiveness of a sacral rod/bone onlay technique for extending spinal fusion to the sacrum.

Methods

To extend posterior spinal fusion to the sacrum, we used either 1 Harrington rod and 1 Luque L rod with sublaminar wires in 14 patients (Group 1) or two rods with sublaminar wires in 51 patients (Group 2) along with abundant autograft and allograft bone covering the ends of the rods.

Results

Diagnoses were Duchenne muscular dystrophy 53, spinal muscular atrophy 4, myopathy 3, limb girdle muscular dystrophy 2, infantile FSH muscular dystrophy 1, cerebral palsy 1, and Friedreich ataxia 1. Mean age at surgery was 14.3 years (±2.2, range 10.9–25.2). Radiographic follow-up (2 years post-surgery or greater) was 6.4 years (±4.4, range 2–25.3). Using the onlay technique, all patients fused with no rod breakage or pseudarthrosis. For the entire series, the mean pre-operative scoliosis was 54.7° (±31.1, range 0°–120°) with post-operative correction to 21.8° (±21.7, range 0°–91°) and long-term follow-up 24° (±22.9, range 0°–94°). For pelvic obliquity, pre-operative deformity was 17.3° (±11.3, range 0°–51°) with post-operative correction to 8.9° (±7.8, range 0°–35°) and long-term follow-up 10.1° (±8.1, range 0°–27°). Five required revision at a mean of 3.3 years post-original surgery involving rod shortening at the distal end. One of these had associated infection.

Conclusion

Lumbosacral stability and long-term sitting comfort have been achieved in all patients. Problems can be minimized by positioning the rods firmly against the sacrum at the time of surgery with a relatively short extension beyond the L₅–S₁ junction. The procedure is valuable in hypotonic non-ambulatory neuromuscular patients whose immobility enhances the success rate for fusion due to diminished stress at the lumbosacral junction. It is particularly warranted for those with osteoporosis and a small, deformed pelvis. Considerable weight loss and lengthy rods not closely apposed to the sacrum at the time of surgery played a major role in patients needing revision.     

Preoperative inspiratory muscle training for patients with severe scoliosis and high-risk pulmonary dysfunction in duchenne muscular dystrophy

Severe spinal collapse and pulmonary function deterioration are so common in patients with Duchenne muscular dystrophy (DMD). The limit for scoliosis surgery has been a minimum forced vital capacity (FVC) of about 30% of predicted value. DMD patients with low %FVC who might benefit from scoliosis surgery have not been being offered surgery. Between 2005 and 2007, a total of 17 DMD patients with FVC of <30% at admission underwent scoliosis surgery. %FVC at admission was 22% (range 16–27%). After admission, they were trained with inspiratory muscle training, using a pulmonary trainer (threshold IMT) for 6 weeks prior to surgery and encouraged to continue the training even after surgery and discharge. %FVC increased in all patients and noted 26% (range 22–31%) the day before surgery. The preoperative scoliosis was 97° (range 81°–130°). All patients had posterior spinal fusion and were extubated on the operative day. No patients developed any respiratory complications. No ventilatory support was needed. The mean ICU stay was 0.5 days (range 0–1 day). The postoperative scoliosis was 31° (range 18°–40°). DMD patients with severe scoliosis and FVC considered too low to permit reasonable surgical risk could undergo surgery after inspiratory muscle training, with no major complications.     

Surgical management of severe scoliosis with high-risk pulmonary dysfunction in Duchenne muscular dystrophy

Between 2005 and 2007, 14 patients who had severe scoliosis in Duchenne muscular dystrophy (DMD) and a poor forced vital capacity (FVC) of <30% at admission underwent scoliosis surgery. FVC on admission was 21.6% (range, 16–27%). The patients were given respiratory muscle training using a pulmonary trainer (Threshold IMT, Philips Respironics, Inc.) for six weeks before operation. FVC increased to 26.2% (range, 22–31%) the day before operation. The mean preoperative scoliosis was 98° (range, 81°–130°). All patients underwent posterior fusion and all-screw construction and were extubated on the operative day. No patients developed any respiratory complications. The postoperative scoliosis was 34° (range, 20°–40°) (65%). FVC remained stable at six weeks after operation. FVC decreased to 19.8% (range, 16–25%) and the mean scoliosis was 35° (range, 23°–40°)(64%) at two years after operation. DMD patients with severe scoliosis and FVC considered too low to permit reasonable surgical risk could undergo surgery and could benefit from surgery.     

Surgical treatment of adolescent idiopathic scoliosis. A comparative analysis

Three hundred and fifty-two patients had a one-stage posterior spinal arthrodesis between 1960 and 1984 using one of four types of instrumentation: a Harrington distraction rod, Harrington distraction and compression rods, Harrington distraction and compression rods with a device for transverse traction, and a Harrington distraction rod with sublaminar wires. All of the patients were female (age-range, eleven to nineteen years), and all had idiopathic scoliosis with a single right or double thoracic curve. The minimum length of follow-up was two years. No significant difference was found among the four groups relative to the amount of correction that was obtained at operation or maintained two years after operation. An average of 13.5 per cent of correction was lost during follow-up in the patients who were treated with postoperative immobilization, and an average of 27 per cent was lost in the patients who were treated with sublaminar wires without immobilization. The use of a straight Harrington rod reduced normal thoracic kyphosis, the addition of a compression rod corrected hyperkyphosis, and the use of a rod with sublaminar wires corrected thoracic hypokyphosis or thoracic lordosis.     

Effect of spinal surgery on lung function in Duchenne muscular dystrophy.

BACKGROUND--The effect on subsequent respiratory function of spinal stabilisation for scoliosis in Duchenne muscular dystrophy is unclear. In order to clarify this clinical problem, changes in the forced vital capacity of a group of children with Duchenne muscular dystrophy who had undergone spinal surgery were measured and compared with a group of children with Duchenne muscular dystrophy who had not had surgery. METHODS--In this retrospective study 17 boys with Duchenne muscular dystrophy who underwent spinal stabilisation at a mean age of 14.9 years (surgical group) were compared with 21 boys with Duchenne muscular dystrophy who had not had surgery (non-surgical group). The mean (SD) Cobb angle of the surgical group at 14.9 years was 57 (16.4) degrees, and of the non-surgical group at 15 years was 45 (29.9) degrees. Forced vital capacity expressed as percentage predicted (% FVC) was measured in total over a seven year period in the surgical group and over 6.5 years in the non-surgical group, and regression equations were calculated. Survival curves for both groups were also constructed. RESULTS--No difference was found between spinal stabilisation (surgical group) and the non-surgical group in the rate of deterioration of % FVC which was 3-5% per year. There was no difference in survival in either group. CONCLUSIONS--Spinal stabilisation in Duchenne muscular dystrophy does not alter the decline in pulmonary function, nor does it improve survival.     

Spinal stabilisation in Duchenne muscular dystrophy.

Of 55 patients with Duchenne muscular dystrophy offered surgical stabilisation of the spine, 32 accepted and 23 refused. We compared both groups pre-operatively and at six-month intervals in respect of survival, forced vital capacity, peak expiratory flow rate and severity of scoliosis. In the nonoperated patients, the forced vital capacity deteriorated by a mean of 8% per annum; in the operated group it remained static for 36 months and diminished slightly thereafter. Spinal stabilisation resulted in an improvement in the peak expiratory flow rate which was maintained for up to five years. In the nonoperated patients the scoliosis progressed from a mean of 37 degrees to a mean of 89 degrees at five years; in the stabilised spines it was improved from a mean of 47 degrees to a mean 34 degrees at five years. There was significantly improved survival in the patients who had undergone spinal stabilisation.     

The effect of posterior spinal fusion on respiratory function in Duchenne muscular dystrophy

Purpose

Posterior instrumented spinal fusion is indicated for progressive scoliosis that develops in Duchenne muscular dystrophy (DMD) patients. Whilst spinal fusion is known to improve quality of life, there is inconsistency amongst the literature regarding its specific effect on respiratory function. Our objective was to determine the effect of scoliosis correction by posterior spinal fusion on respiratory function in a large cohort of patients with DMD. Patients with DMD undergoing posterior spinal fusion were compared to patients with DMD not undergoing surgical intervention.

Methods

An observational study of 65 patients with DMD associated scoliosis, born between 1961 and 2001: 28 of which underwent correction of scoliosis via posterior spinal fusion (Surgical Group) and 37 of which did not undergo surgical intervention (Non-Surgical Group). Pulmonary function was assessed using traditional spirometry. Comparisons were made between groups at set times, and by way of rates of change over time.

Results

There was no correlation between the level of respiratory dysfunction and the severity of scoliosis (as measured by Cobb angle) for the whole cohort. The Surgical Group had significantly worse respiratory function at a comparable age pre-operatively compared to the Non-Surgical Group, as measured by per cent predicted forced vital capacity (p = 0.02) on spirometry. The rate of decline of forced vital capacity and per cent predicted forced vital capacity was not slowed following surgery compared to the non-operated cases. There was no significant difference in survival between the two groups.

Conclusions

Severity of scoliosis was not a key determinant of respiratory dysfunction. Posterior spinal fusion did not reduce the rate of respiratory function decline. These two points suggest that intrinsic respiratory muscle weakness is the main determinant of decline in respiratory function in DMD.     

Operative treatment of scoliosis in proximal spinal muscular atrophy: results of 41 patients

Introduction

The early development of progressive scoliosis with pelvic obliquity is the most significant orthopaedic problem for non-ambulatory children with spinal muscular atrophy (SMA).

Patients

24 SMA patients were operated on for scoliosis using the ISOLA^? system and 17 patients using a telescopic rod. The average age at spinal surgery was 12.3?years (6.5?C22.7) in the ISOLA^? group and 6.7?years (4.8?C10.9) in the telescopic rod group.

Results

The Cobb angle was corrected on average from pre-operative 83°(54°?C120°) to post-operative 39°(5°?C70°) in the ISOLA^? group and, respectively, from 62°(28°?C86°) to 18°(0°?C34°) in the telescopic rod group. Mean loss of correction at mean follow-up of 6?years (3?C10) was 6°(0°?C33°) in the ISOLA^? group and at mean follow-up of 8.6?years (3?C12) 13°(0°?C49°) in the telescopic rod group excluding the patients with rod failure. The vital capacity is not worsened by these operations in comparison to the natural course. After telescopic rods were implanted, there were some unsatisfactory results due to crankshaft phenomenon and an increase of pelvic obliquity.

Conclusion

Our recommendation for non-ambulatory SMA patients is to have definitive stabilisation using multisegmental instrumentation, starting from the age of 10 to 12?years.     

Diaphragm thickness and inspiratory strength in patients with Duchenne muscular dystrophy

BACKGROUND: There is little information on the morphometric characteristics of the diaphragm in patients with Duchenne muscular dystrophy. METHODS: The thickness of the diaphragm was measured at the zone of apposition using B mode ultrasonography in 10 boys with Duchenne muscular dystrophy of mean (SD) age 10.3 (1.3) years and 12 normal controls of mean (SD) age 11.3 (2.0) years during relaxation (DiTrelax) and during maximum effort inspiratory manoeuvres (DiTPimax) at functional residual capacity. RESULTS: DiTrelax was greater in the patients with Duchenne muscular dystrophy (1.74 (0.21) mm) than in controls (1.48 (0.20) mm), mean difference (95% CI) 0.26 (0.08 to 0.44), despite considerable impairment of maximum effort inspiratory mouth pressure (Pimax) (patients with Duchenne muscular dystrophy -37 (8) cm H2O, controls -80 (33) cm H2O), mean difference (95% CI) 43 (65 to 20). During a Pimax manoeuvre, compared with measurements taken during relaxation, the diaphragm thickened 1.6 times in patients with Duchenne muscular dystrophy and 2.3 times in controls (DiTPimax 2.62 (0.7) mm and 3.5 (0.85) mm, respectively), mean difference (95% CI) - 0.88 (-1.58 to -0.18). CONCLUSIONS: Resting diaphragm thickness is increased in young patients with Duchenne muscular dystrophy with impaired respiratory muscle force. This finding could be analogous to the pseudo-hypertrophy that is observed in some limb muscle groups.


     

Combined staged anterior and posterior correction and fusion of the spine in scoliosis following poliomyelitis.

The problems with severe forms of scoliosis following poliomyelitis include the associated muscle imbalance, soft tissue contractures and pelvic obliquity. Such deformities militate against optimal correction and maintenance of that correction and their treatment is often marred by pseudarthroses. Seventeen patients with an average curve of 93 degrees have been treated and followed for up to 38 months. Preliminary traction was used in 8 patients, then a staged anterior and posterior correction and fusion was done, using Dwyer's instrumentation of the major curve in all and a Harrington rod to supplement the posterior fusion in eleven patients. With this technique the major curve was corrected by 80 per cent with an average 2 per cent loss over 18 months. No pseudarthroses were seen when the Harrington rod was used. Great care must be taken if halo-pelvic traction is to be used for patients with pelvic obliquity, for preliminary correction halo-femoral traction will often be adequate. In the more severe forms of paralytic scoliosis a combined staged anterior and posterior correction and fusion should be considered if the aim is maximal correction of the scoliosis and avoidance of pseudarthroses.     

Operative Treatment of Scoliosis with Harrington Instrumentation Technique

Thirty-five patients with scoliosis were treated with posterior fusion including the Harrington instrumentation technique. The operation was followed by a 1-year period of treatment in a Milwaukee brace. The patients had a thoracic or a thoracolumbar curve averaging 74°. The mean initial correction was 45 per cent, and the mean final correction 33 per cent, after 2 3/4 years. There were no cases of pseudarthrosis and only one case of transient paresis. There were no deaths. It is concluded that these results are satisfactory and that the method is a safe one in experienced hands.     

Adult idiopathic scoliosis treated with Luque or Harrington rods and sublaminar wiring

We reviewed the results of spinal arthrodesis that was performed, with sublaminar wires that were attached to either double L-shaped Luque rods or to a Harrington rod, in forty-two adults who had idiopathic scoliosis. The minimum length of follow-up was two years; the maximum, five years; and the average, three years. The average scoliosis measured 67 degrees preoperatively, was corrected to 37 degrees at operation, and was 44 degrees at the time of follow-up. The final correction averaged 34 per cent. A single Harrington rod and multiple sublaminar wires were used in thirty-one patients. Eighteen of the thirty-one patients had a posterior arthrodesis only and thirteen, a preliminary anterior arthrodesis followed by a posterior arthrodesis. Eleven patients had instrumentation with double L-shaped Luque rods; six of them had posterior arthrodesis only and five, a preliminary anterior arthrodesis followed by a posterior arthrodesis. One patient had neurological deficit that was related to the operation. Three patients had a pseudarthrosis, which was in the lumbar area in all of them. All three patients had had only a posterior operation. No statistically significant difference in the amount of final correction was demonstrated between the subgroups.     

Subarachnoid bupivacaine decreases spinal cord blood flow in dogs

Eigtheen mongrel dogs were randomized into two equal groups. Cervical, thoracic and lumbosacral spinal cord and spinal dural blood flows were measured using the radioactive microsphere technique. Blood flow determinations were made prior to, and 20 and 40 minutes following lumbar subarachnoid injection of: (1) 0.4 per cent bupivacaine (20 mg), or (2)0.4 per cent bupivacaine (20 mg) with 1/25,000 epinephrine (200 μg). In dogs given subarachnoid bupivacaine or bupivacaine with epinephrine, the maximum decrease in mean arterial blood pressure (33 per cent) occurred at 40 minutes post-injection. Cardiac index decreased in dogs given subarachnoid bupivacaine (197 ± 11 ml·kg^-1·min^-1 controlvs. 141 ± 19 ml·kg^-1 min^-1 at 40 minutes), while it increased in dogs given bupivacaine with epinephrine (201 ± 11ml·kg^-1·min^-1 - control vs. 252 ± 15 ml · kg^-1 · min^-1 at 40 minutes). Dogs receiving subarachnoid bupivacaine demonstrated a significant decrease in spinal cord blood flow to all regions. Dogs receiving subarachnoid bupivacaine with epinephrine demonstrated a significant decrease in thoracic and lumbosacral spinal cord blood flow; however, cervical cord blood flow remained unchanged. Thoracic and lumbosacral dural blood flows were significantly decreased in both groups following subarachnoid injection. Subarachnoid bupivacaine 0.4 per cent (20 mg) and 0.4 per cent with epinephrine 1/25,000 (200 μg) decrease spinal cord and spinal dural blood flow in dogs.     

Oxygen treatment of sleep hypoxaemia in Duchenne muscular dystrophy.

Patients with Duchenne muscular dystrophy develop progressive ventilatory muscle weakness and often die of respiratory complications. Recurrent, often profound, hypoxaemia has been shown in a previous study by this group to occur during rapid eye movement (REM) sleep in these patients before they develop sleep symptoms. In this study the efficacy and physiological effects of nocturnal oxygen in such patients have been assessed. Seven patients with Duchenne muscular dystrophy (age range 16-22 years; mean vital capacity 1.37 litres) with normal arterial blood gas tensions when awake were investigated by standard overnight polysomnography on an acclimatization night followed by two successive nights on which they received room air and nasal oxygen (2 litres/min) respectively in random order. Total sleep time, proportion of REM and non-REM sleep, and frequency and duration of arousals were similar on the two nights. When breathing air six of the seven subjects developed oxygen desaturation of more than 5% during REM sleep. With oxygen only one subject showed any oxygen desaturation exceeding 2.5%. Oxygen desaturation was associated with periods of hypopnoea or cessation of respiratory effort. The mean duration of episodes of hypopnoea and apnoea was prolonged during oxygen breathing by 19% and the mean duration of episodes during REM sleep by 33% (the proportion of REM sleep associated with hypopnoea and apnoea increased in all subjects). Heart rate in non-REM sleep fell by 9.3%; heart rate variation in REM and non-REM sleep was unchanged. These acute studies show that oxygen reduces the sleep hypoxaemia associated with respiratory muscle weakness; whether long term treatment will be possible or desirable is not clear as oxygen potentiates the underlying ventilatory disturbance.     

Early ambulation following spinal fusion and Harrington instrumentation in idiopathic scoliosis.

Eighty-six patients with idiopathic scoliosis managed by Harrington instrumentation and spinal arthrodesis were ambulated 10 days following surgery. Preoperative reduction of the curves was obtained by Cotrel traction and modified Cotrel localizer cast. Patients were kept immobilized in plaster cast for 7 months following operation. No significant loss of correction was found in these patients ambulated early as compared to a previous group kept recumbent for 3 to 6 months and reported by the authors (DBL). The only exception to this was a patient with double structural curve patterns. A successful surgical program for most cases of idiopathic scoliosis included: (1) Preoperative reduction and balancing of curves by non-skeletal traction and/or correction body cast; (2) Meticulous spinal arthrodesis and employment of Harrington distraction internal fixation; (3) Autogenous iliac bone graft; (4) Ambulation at two weeks following surgery in a well fitting body cast and removal of this cast after 7 months. Deep infection rate was 1 per cent without the use of routine prophylatic antibiotics. One neurological complication resulted from the use of a single distraction rod bridging two curves where the rod was not prebent to allow for kyphosis. There were no pseudarthroses. The average follow-up was 28 months with a range of 18-39 months.     

Operative Treatment of Scoliosis with the Harrington Instrumentation Technique

Preliminary results of treatment of scoliosis with the Harrington instrumentation technique in 80 patients are presented. The curve correction at operation averaged 43.4 per cent with the best results being achieved in idiopathic single curves (49.3 per cent). Most of the patients had been treated conservatively for a long time prior to operation, and the curves were rather stiff. The initial loss of correction was 3.2°, and the overall loss at 2 years postoperatively averaged 6.5° in 28 patients. Complications occurred in 22.5 per cent of the patients, most often at the upper hook site. Serious complications were rare. It is concluded that the Harrington instrumentation technique is an effective means of treatment of scoliosis.     

Operative Treatment of Scoliosis with Harrington Instrumentation Technique

Thirty-five patients with scoliosis were treated with posterior fusion including the Harrington instrumentation technique. The operation was followed by a 1-year period of treatment in a Milwaukee brace. The patients had a thoracic or a thoracolumbar curve averaging 74°. The mean initial correction was 45 per cent, and the mean final correction 33 per cent, after 2 3/4 years. There were no cases of pseudarthrosis and only one case of transient paresis. There were no deaths. It is concluded that these results are satisfactory and that the method is a safe one in experienced hands.     

Increases in heart rate and systolic blood pressure in anesthetized dogs affected with X-linked muscular dystrophy after cisatracurium administration: a retrospective study

Background: Most patients affected with Duchenne muscular dystrophy (DMD) present with arrhythmias and cardiomyopathies. Drugs which potentially may induce tachycardia or hypertension could precipitate acute cardiac failure in these patients and should be avoided. Methods: Thirty anesthesia records of five experimental male golden retriever cross‐bred dogs affected with X‐linked muscular dystrophy (GRDM), a model of DMD, were retrospectively reviewed (DMD group). Anesthesia records were compared with those of 10 golden retriever dogs not affected with muscular dystrophy (control group). Records were excluded if dogs received anticholinergics or vasoactive amines. Anesthesia was induced with fentanyl followed by propofol, both intravenously. After orotracheal intubation, all dogs’ lungs were mechanically ventilated. Anesthesia was maintained with infusion of fentanyl and propofol (DMD group) or isoflurane in oxygen (control group). Pure O₂ was provided to the DMD group. Cisatracurium (0.1 mg·kg^?1) was administered intravenously to all dogs. Five‐min interval recordings of HR and systolic blood pressures (SAP) were obtained. Results: Immediately after the administration of cisatracurium, absolute values for HR and SAP significantly increased by 78.3 ± 37.0 b·min^?1 (115.4 ± 64.9%) and 33.0 ± 28.3 mmHg (33.5 ± 31.2%), respectively, in all DMD dogs and remained significantly increased for 10 and 30 min, respectively. Dogs in the control group did not show significant increases in HR or SAP after cisatracurium administration. All dogs recovered from anesthesia without complications. Conclusion: In this report, increases in HR and SAP could be associated with the administration of cisatracurium in individuals affected with X‐linked muscular dystrophy. These cardiovascular changes deserve further investigation.     

Neuromuscular blockade in infants following intramuscular succinylcholine in two or five per cent concentration

This study determined the characteristics of the neuromuscular block which followed intramuscular succinylcholine 4 mg.kg^-1 in 20 infants during halolhane anaesthesia. The infants were divided into two groups of ten; the first received succinylcholine in two per cent solution and the second in five per cent solution. The mean maximum depression of the first twitch of the train-of-four (TI) was 89.7 ± 5.0 per cent in 4.0 ± 0.6min, and the mean full recovery of TI occurred in 15.6 ±0.9 min after injection. The maximum block achieved and the onset and recovery times were not affected by the concentration used. Depolarizing block, with equal depression of all twitches of the train-of-four was observed during the onset of neuromuscular blockade. During recovery, phase II block, as determined by a train-of-four ratio (T4/T1) of 0.5 or less, occurred frequently at TI recovery of 25–50 per cent, but was not associated with prolonged paralysis. It is concluded that the onset time of 4 min for intramuscular succinylcholine 4 mg.kg^-1 may be too long for emergency use in infants, and no improvement is obtained by increasing the concentration of injected succinylcholine from two to five per cent.

     

Progression of scoliosis in Duchenne muscular dystrophy

We reviewed the clinical charts and spinal radiographs of fifty-one boys who had Duchenne muscular dystrophy, had not had surgical treatment of the spine, and had been followed until death. All had scoliosis. None of the following variables was useful in predicting which curves would become severe: age when the patient initially walked, age when he ceased walking, age at onset of spinal collapse, surgical release of the iliotibial bands, or age at the time of death. Radiographs were made within eighteen months before death for thirty-three patients; in thirty-one of them, the final curve exceeded 40 degrees and in seventeen, 90 degrees. For the remaining eighteen patients, final radiographs were made more than eighteen months before death; at that time, eight of them already had a curve of more than 90 degrees. Although there was a relationship between extension of the lumbar spine and severity of scoliosis at the time of final follow-up, early maintenance of the lumbar spine in extension rarely prevented the development of a severe curve. For most of the patients who had a severe curve, sitting was difficult and was accompanied by breakdown of the skin and pain. When a patient's curve exceeded 35 degrees, the vital capacity usually was less than 40 per cent of the predicted normal value. Therefore, when walking becomes impossible for boys who have Duchenne muscular dystrophy, routine spinal arthrodesis should be considered.