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Factors in 171 navy diving decompression accidents occurring between 1960-1969.

Comparisons were made between the incidence of specific factors in U.S. Navy decompression accidents and the incidence of these factors in routine (nonexperimental) U.S. Navy operational dives. It was found that decompression accidents are disproportionately high among a) air dives less than 140 ft which have bottom times of 30 min or less and air dives greater than 140 ft which have bottom times of more than 15 min, b) Divers First Class, c) older divers, and d) dives which do not involve work or divers which require heavy work. Repetitive dives have a lower decompression accident rate than expected. Decompression accidents were not disproportionately high for any category of body build. These results indicate that the present U.S. Navy decompression tables are extremely safe (5 decompression accidents/10,000 dives), and do not appear to require modification. Future decompression research may be directed toward analyzing the relationship of work and aging to physiological processes involved in decompression. In addition, the present findings should be cross-validated using more recent accident and operational diving data.

Accidents↗

Changes in hemostatic parameters in fish following rapid decompression.

The effect of rapid decompression on the stress-accelerated blood coagulation system of male and fingerling coho salmon (Oncorhynchus kisutch) was examined after simulated 100- and 200-fsw dives. Blood samples taken either through a dorsal aorta cannula or from a severed caudal peduncle were analyzed for total plasma protein and fibrinogen concentrations, prothrombin times (PT), and partial thromboplastin times (PTT). The effect of mild decompression (100-fsw) on the hemostatic mechanism of both adult and fingerling coho salmon indicated an alternating fibrinogen concentration, declining from normal levels 1 min after decompression, followed by an increase 10 to 15 min later with an eventual loss of fibrinogen to one half the original level an hour after decompression. Partial thromboplastin times were found to increase 10 to 15 min after decompression occurred. Prothrombin times showed an increase 1 hour after decompression in adult salmon, whereas in fingerlings, prothrombin times increased almost immediately from normal levels. The effect of severe decompression (200-fsw) showed similar trends, but at an accelerated rate. It was concluded that both mild and severe decompression activates the hemostatic mechanism of fish which may eventually result in consumption coagulopathy at a greater rate than reported for experimental mammals.

Age Factors↗

[Decompression of deep divers].

For industrial saturation dives over 50 m, Heliox (He-O2) is now used routinely as respiratory gas mix. The decompression after such dives has been investigated thoroughly as well on the animal (minipig, monkeys) as on humans. Results show that for a given ascending speed, the number of bubbles detectable by the Doppler method in the bloodstream rises according to the maximal depth. The incidence of decompression accidents follows the same trend. This finding prompted us to adopt since 1979 slower decompression speeds. Moreover we modified the ascension profile, using henceforth a linear decompression in maintaining a constant speed for a given partial oxygen pressure. For our research program Hydra, we replaced in part Helium by Hydrogen in the respiratory gas mix. We were thus able to do the first hydrogen saturation decompression between 450 and 200 meters, during our Hydra V (1985) experiment. During our following diving research program Hydra VI (1986), 8 divers were decompressed under Hydreliox (H2-He-O2) mix from 500 to 300 m by eliminating hydrogen by chemical means. We used for this purpose a dehydrogenation apparatus developed by our engineering team. These decompressions took place without any difficulty and only a low number of bubbles detected. It is therefore possible to use decompression speeds for hydrogen and helium which are very similar. A confirmatory experiment on mice, where we exposed them to a 2000 m depth dive under Hydreliox (H2-He-O2), gave good results. This gives us the possibility, to perform gas exchange studies on small animals and to extrapolate the results to humans.

Animals↗

Relationship between CO2 levels and decompression sickness: implications for disease prevention.

Extensive data concerning the incidence of decompression sickness among workers participating in the deepest caisson operation in Japan to date have been collected and analyzed for the period April through August, 1976. When the bottom pressure was between 3.0 and 3.2 ATA, the incidence of decompression sickness was 3.05%; subsequently, the incidence was only 0.96% between 3.2 and 3.4 ATA. The man lock (i.e., decompression chamber) had never been ventilated during the former group of decompressions and the level of CO2 had ranged between 1.8 and 2.3% (v/v); in the latter group of decompressions, the CO2 level ranged between 0.3 and 0.8% with ventilation. All other conditions, including the decompression table used, were the same. Moreover, based upon the nature of the muscular activity required of the caisson workers just prior to decompression, their most common site of affliction was found to lie within the body region where the highest tissue tensions of CO2 would be expected during decompression.

Adult↗

Evaluation of different decompression schedules by an agarose gel bubble technique.

It is well known that diving decompression schedules vary according to country and that Navy schedules are often different from civilian ones. Furthermore, it is difficult to compare them effectively, because the bends incidence for each schedule is rarely known accurately. We have evaluated various decompression schedules by an agarose gel bubble technique in which the appearance of bubbles in a dry chamber at a controlled temperature was used, and we report this as a useful method of evaluating decompression tables. It is generally accepted that decompression sickness symptoms are due to bubble formation and the body's subsequent physiological reaction. Individual differences and physical conditions are also influential factors. However, bubble formation appears to be the most important factor in initiating symptoms. As the number of bubbles is influenced by the physical decompression ratio, it can be estimated which decompression schedule is more likely to minimize the number of bubbles. Nine decompression schedules were studied in this experiment: U.S. Navy Table, French Navy Table, Japanese Standard Decompression Schedule Numbers 1 and 2, Royal Naval Physiological Laboratory Table, French Ministry of Labor Table, Model 1 Table by Mano et al., Washington State Table, and Blackpool Table.

Decompression↗

Cardiovascular pressures with venous gas embolism and decompression.

Venous gas embolism (VGE) is reported with decompression to a decreased ambient pressure. With severe decompression, or in cases where an intracardiac septal defect (patent foramen ovale) exists, the venous bubbles can become arterialized and cause neurological decompression illness. Incidence rates of patent foramen ovale in the general population range from 25-34% and yet aviators, astronauts, and deepsea divers who have decompression-induced venous bubbles do not demonstrate neurological symptoms at these high rates. This apparent disparity may be attributable to the normal pressure gradient across the atria of the heart that must be reversed for there to be flow patency. We evaluated the effects of: a) venous gas embolism (0.025, 0.05 and 0.15 ml.kg-1.min-1 for 180 min.); b) hyperbaric decompression; and c) hypobaric decompression on the pressure gradient across the left and right atria in anesthetized dogs with intact atrial septa. Left ventricular end-diastolic pressure was used as a measure of left atrial pressure. In a total of 92 experimental evaluations in 22 dogs, there were no reported reversals in the mean pressure gradient across the atria; a total of 3 transient reversals occurred during the peak pressure gradient changes. The reasons that decompression-induced venous bubbles do not consistently cause serious symptoms of decompression illness may be that the amount of venous gas does not always cause sufficient pressure reversal across a patent foramen ovale to cause arterialization of the venous bubbles.

Altitude↗

Endoscopic transnasal orbital decompression.

Orbital decompression for dysthyroid orbitopathy has traditionally been performed through either an external or a transantral approach. The advent of intranasal endoscopes allowed for the development of a transnasal approach for medial and inferior orbital wall decompression. Using this approach, orbital decompressions were performed on 13 orbits in eight patients with severe complicated dysthyroid orbitopathy. Simultaneous bilateral lateral orbitotomies were performed on five patients. Walsh-Ogura decompressions and lateral orbitotomies were performed on two orbits. When combined with lateral orbitotomy, Hertel measurements improved an average of 5.7 mm in orbits decompressed transnasally and 4.5 mm in orbits decompressed with a Walsh-Ogura approach. Transnasal decompression alone improved Hertel measurements an average of 4.7 mm. Visual acuity improved in three of four patients with optic neuropathy, and in all patients with exposure keratopathy. We conclude that the endoscopic transnasal approach provides comparable decompression to traditional methods while avoiding the morbidity of an external ethmoidectomy or Caldwell-Luc antrotomy.

Adult↗

Transcystic biliary decompression after direct laparoscopic exploration of the common bile duct.

BACKGROUND: A purpose-designed transcystic common bile duct (CBD) decompression cannula is described for use as an alternative to T-tube insertion following laparoscopic direct CBD exploration. This permits safe primary closure of the choledochotomy. METHODS: Following direct supraduodenal laparoscopic clearance of large common bile duct stones, the biliary decompression cannula is inserted percutaneously inside its peel-away sheet over a guide-wire into the CBD via the cystic duct. When in place, the cannula is secured to the cystic duct by two catgut extracorporeal Roeder knots and the choledochotomy is then closed. The terminal multiperforated S-shaped segment of the Cuschieri biliary decompression cannula prevents postoperative dislodgement. RESULTS: Transcystic decompression of the extrahepatic biliary tract using the Cuschieri cannula has been used in 12 patients who underwent laparoscopic supraduodenal CBD exploration for large or occluding stones. There was no instance of postoperative dislodgement of the cannula and all patients had effective drainage of the common bile duct (average 300 ml bile per 24 h). The procedure was uncomplicated in all but one patient who developed self-limiting leakage from the CBD suture line in the early postoperative period. The median hospital stay after surgery was 4 days, with a range of 3 to 10 days. The cystic duct decompression cannula was capped and sealed under an occlusive dressing at the time of discharge. Removal of the cannula was carried out without any complications as a day case 11-16 days after surgery. CONCLUSIONS: Transcystic biliary decompression is safe and effective. The experience with is use indicates that compared to T-tube drainage, transcystic decompression may accelerate recovery and reduce the hospital stay in patients following laparoscopic direct exploration of the CBD. Its insertion is less technically demanding than placing a T-tube through the choledochotomy. Transcystic decompression with complete primary closure of the CBD realizes the full benefits of the single-stage management of common bile duct calculi and permits confirmation of complete stone clearance after surgery.

Aged↗

Fetal ovarian cyst decompression to prevent torsion.

BACKGROUND/PURPOSE: Neonates who have ovarian torsion caused by an ovarian cyst often lose their ovary because the torsion and infarction occurred antenatally. Because ultrasound scan has been so effective in diagnosing ovarian cysts in utero, we have a better understanding of their natural history and can select appropriate cases for cyst decompression in utero to prevent torsion. The authors reviewed experience with seven fetuses who had fetal ovarian cyst. METHODS: During a 26-month period, seven patients were referred for the evaluation of fetal ovarian cyst. The mean gestational age at presentation was 31.9 +/- 3.6 weeks (+/-SD; range, 27 to 37 weeks). There was no history of maternal risk factors such as diabetes mellitus or fetal risk factors such as hyperthyroidism or placentomegally. All seven cases involved isolated unilateral cysts without associated anomalies or chromosomal abnormalities. Mean initial cyst diameter was 3.4 +/- 1.7 cm (+/-SD; range, 1 to 6.1). Indications used for ovarian cyst decompression included anechoic cysts with a diameter > or =4 cm, a cyst "wandering" about the abdomen on serial sonograms, or demonstrating rapid enlargement (>1 cm/wk). RESULTS: All but one cyst progressed in size during observation. One fetal ovarian cyst (diameter, 2 cm) subsequently regressed spontaneously and another (diameter, 2.1 cm) stabilized during prenatal ultrasound surveillance. One "cyst" observed with a diameter of 3.5 cm proved to be a persistent cloaca. Four fetal ovarian cysts met criteria for decompression. Because of fetal position, decompression could not be performed in one. One cyst (seen before defining criteria for decompression) with a diameter of 5 cm was observed only and underwent torsion. Two cysts (diameters, 6.1 cm and 4 cm) were decompressed in utero under local anesthesia with ultrasound guidance, of 95 mL and 35 mL, respectively. High cyst fluid progesterone (12,041 and 1,990 ng/dL, respectively) and testosterone (1,298 and 2,900 ng/dL, respectively) confirmed the etiology of the cyst as ovarian. Neither cyst recurred, and postnatal ultrasound scan confirmed resolution. There was no maternal or fetal morbidity or mortality and only the patient observed before development of criteria for decompression lost her ovary because of torsion. CONCLUSIONS: Fetal ovarian cysts tend to present as isolated unilateral lesions in normal fetuses in the third trimester. Spontaneous regression of fetal ovarian cysts may occur. Fetal ovarian cyst decompression, in select cases, may preserve ovaries at risk for torsion.

Female↗

Orbital fat removal. Decompression for Graves orbitopathy.

BACKGROUND: Orbital decompression has been used to describe surgical procedures that remove some portion of the orbital walls to reduce pressure on the orbital contents. Substantial morbidity associated with these procedures includes infraorbital anesthesia, worsened extraocular motility, globe displacement, and blindness. The authors believe that orbital contents also may be decompressed by removing orbital fat. METHODS: Eighty-one patients with nonactive Graves orbitopathy were selected for orbital fat decompression based on the presence of proptosis and associated signs and symptoms to avoid bone removal. Soft-tissue analysis by computed tomography (CT) scan showed distended pockets of fat extending into the intraconal space, which were removed through medial-upper and lateral-lower anterior orbitotomies. Decompression with bone removal was reserved for those few patients with compressive optic neuropathy unresponsive to medical treatment and those patients with residual deforming exophthalmos after fat removal. RESULTS: One hundred fifty-eight fat decompressions were performed on 81 patients over 9 years. The authors measured an average reduction in proptosis of 1.8 mm (range, 0-6.0 mm). The greatest average reduction in proptosis (3.3 mm) was produced in patients with preoperative Hertel measurements of greater than 25.0 mm. Morbidity was limited to temporary motility impairment of the inferior oblique in two patients. CONCLUSION: The concept of orbital decompression can include removal of orbital fat to reduce proptosis, eliminate symptoms, and improve appearance with far less morbidity than when bone decompression is used as the primary decompressive procedure.

Adipose Tissue↗

A comparison of active compression-decompression cardiopulmonary resuscitation with standard cardiopulmonary resuscitation for cardiac arrests occurring in the hospital.

BACKGROUND: Recent studies have demonstrated improved cardiopulmonary circulation during cardiac arrest with the use of a hand-held suction device (Ambu CardioPump) to perform active compression-decompression cardiopulmonary resuscitation (CPR). The purpose of this study was to compare active compression-decompression with standard CPR during cardiac arrests in hospitalized patients. METHODS: All patients over the age of 18 years who had a witnessed cardiac arrest while hospitalized at our center were enrolled in this trial; they were randomly assigned according to their medical-record numbers to receive either active compression-decompression or standard CPR. The study end points were the rates of initial resuscitation, survival at 24 hours, hospital discharge, and neurologic outcome. Compressions were performed according to the recommendations of the American Heart Association (80 to 100 compressions per minute; depth of compression, 3.8 to 5.1 cm [1.5 to 2 in.]; and 50 percent of the cycle spent in compression). RESULTS: Sixty-two patients (45 men and 17 women) with a mean age (+/- SE) of 68 +/- 2 years were entered into the trial. Sixty-two percent of the patients who underwent active compression-decompression were initially resuscitated, as compared with 30 percent of the patients who received standard CPR (P < 0.03); 45 percent of the patients who underwent active compression-decompression survived for at least 24 hours, as compared with 9 percent of patients who underwent standard CPR (P < 0.004). Two of the 62 study patients survived to hospital discharge; both were randomly assigned to receive active compression-decompression. Neurologic outcome, as measured by the Glasgow coma score, was better with active compression-decompression (8.0 +/- 1.3) than with standard CPR (3.5 +/- 0.3; P < 0.02). CONCLUSIONS: In this preliminary study, we found that, as compared with standard CPR, active compression-decompression CPR improved the rate of initial resuscitation, survival at 24 hours, and neurologic outcome after in-hospital cardiac arrest. Larger trials will be required to assess the potential benefit in terms of long-term survival.

Aged↗

A meta-analysis of selective versus routine nasogastric decompression after elective laparotomy.

OBJECTIVE: A meta-analysis of all published clinical trials comparing selective versus routine nasogastric decompression was performed in an attempt to evaluate the need for nasogastric decompression after elective laparotomy. BACKGROUND: Many studies have suggested that routine nasogastric decompression is unnecessary after elective laparotomy and may be associated with an increased incidence of complications. Despite these reports, many surgeons continue to practice routine nasogastric decompression, believing that its use significantly decreases the risk of postoperative nausea, vomiting, aspiration, wound dehiscence, and anastomotic leak. METHODS: A comprehensive search of the English language medical literature was performed to identify all published clinical trials evaluating nasogastric decompression. Twenty-six trials (3964 patients) met inclusion criteria. The outcome data extracted from each trial were subsequently "pooled" and analyzed for significant differences using the Mantel-Haenszel estimation of combined relative risk. RESULTS: Fever, atelectasis, and pneumonia were significantly less common and days to first oral intake were significantly fewer in patients managed without nasogastric tubes. Meta-analysis based on study quality revealed significantly fewer pulmonary complications, but significantly greater abdominal distension and vomiting in patients managed without nasogastric tubes. Routine nasogastric decompression did not decrease the incidence of any other complication. CONCLUSIONS: Although patients may develop abdominal distension or vomiting without a nasogastric tube, this is not associated with an increase in complications or length of stay. For every patient requiring insertion of a nasogastric tube in the postoperative period, at least 20 patients will not require nasogastric decompression. Routine nasogastric decompression is not supported by meta-analysis of the literature.

Elective Surgical Procedures↗

Effects of abdominal decompression on cardiopulmonary function and visceral perfusion in patients with intra-abdominal hypertension.

OBJECTIVE: Increased intra-abdominal pressure (IAP) compromises cardiopulmonary function and visceral perfusion. Our goal was to characterize acute changes in these subsystems associated with operative abdominal decompression. PATIENT POPULATION: A series of 11 consecutive injured patients monitored with a pulmonary artery catheter and nasogastric tonometer in whom operative decompression was performed. Indications for decompression included oliguria or progressive acidosis despite aggressive resuscitation in the presence of elevated IAP (>25 mm Hg). MAIN OUTCOME MEASURES: Studied hemodynamic variables included pulmonary artery occlusion pressure (PAOP), right ventricular end-diastolic volume index (RVEDVI), and cardiac index (CI). Pulmonary variables included shunt fraction (Qs/Qt) and dynamic compliance (Cdyn). Visceral perfusion was assessed using hourly urine output 4 hours before and after decompression (UOP) and gastric intramucosal pH (pHi). Mean values before and after decompression were compared using the paired t test. Linear regression and Fisher's z transformation were used to evaluate the relationships between RVEDVI, PAOP, CI, and IAP. IAP was transduced via bladder pressures. Significance was defined as p < 0.05. Data are expressed as means+/-SD. RESULTS: IAP decreased with decompression (49+/-11 to 19+/-6.8 mm Hg; p < 0.0001). RVEDVI improved independent of CI and correlated better (p < 0.01) with CI (r =0.49, p=0.04) than PAOP did (r=-0.36, p=0.09). PAOP correlated significantly with IAP (r=0.45, p=0.04). Decompression resulted in significant improvements in Qs/Qt, Cdyn, UOP, and pHi. CONCLUSION: Abdominal decompression in patients with increased IAP improves preload, pulmonary function, and visceral perfusion. Elevated IAP has important effects on PAOP, which makes the PAOP an unreliable index of preload in these patients.

Abdominal Injuries↗

Viscoelastic relaxation and regional blood flow response to spinal cord compression and decompression.

STUDY DESIGN: To better understand the relationships between primary mechanical factors of spinal cord trauma and secondary mechanisms of injury, this study evaluated regional blood flow and somatosensory evoked potential function in an in vivo canine model with controlled velocity spinal cord displacement and real-time piston-spinal cord interface pressure feedback. OBJECTIVES: To determine the effect of regional spinal cord blood flow and viscoelastic cord relaxation on recovery of neural conduction, with and without spinal cord decompression. SUMMARY OF BACKGROUND DATA: The relative contribution of mechanical and vascular factors on spinal cord injury remains undefined. METHODS: Twelve beagles were anesthetized and underwent T13 laminectomy. A constant velocity spinal cord compression was applied using a hydraulic loading piston with a subminiature pressure transducer rigidly attached to the spinal column. Spinal cord displacement was stopped when somatosensory evoked potential amplitudes decreased by 50% (maximum compression). Six animals were decompressed 5 minutes after maximum compression and were compared with six animals who had spinal cord displacement maintained for 3 hours and were not decompressed. Regional spinal cord blood flow was measured with a fluorescent microsphere technique. RESULTS: At maximum compression, regional spinal cord blood flow at the injury site fell from 19.0 +/- 1.3 mL/100 g/min to 12.6 +/- 1.0 mL/100 g/min, whereas piston-spinal cord interface pressure was 30.5 +/- 1.8 kPa, and cord displacement measured 2.1 +/- 0.1 mm (mean +/- SE). Five minutes after the piston translation was stopped, the spinal cord interface pressure had dissipated 51%, whereas the somatosensory evoked potential amplitudes continued to decrease to 16% of baseline. In the sustained compression group, cord interface pressure relaxed to 13% of maximum within 90 minutes; however, no recovery of somatosensory evoked potential function occurred, and regional spinal cord blood flow remained significantly lower than baseline at 30 and 180 minutes after maximum compression. In the six animals that underwent spinal cord decompression, somatosensory evoked potential function and regional spinal cord blood flow recovered to baseline 30 minutes after maximum compression. CONCLUSIONS: Despite rapid cord relaxation of more than 50% within 5 minutes after maximum compression, somatosensory evoked potential conduction recovered only with early decompression. Spinal cord decompression was associated with an early recovery of regional spinal cord blood flow and somatosensory evoked potential recovery. By 3 hours, spinal cord blood flow was similar in both the compressed and decompressed groups, despite that somatosensory evoked potential recovery occurred only in the decompressed group.

Animals↗

Intraoperative dermatomal evoked potential monitoring fails to predict outcome from lumbar decompression surgery.

STUDY DESIGN: Thirty-three patients with single-level, unilateral lumbosacral radiculopathy underwent micro-decompression and intraoperative dermatomal evoked potential monitoring. Side-to-side latency asymmetry was calculated. A criteria for "abnormal" was defined. Intraoperative dermatomal evoked potentials were obtained before and after decompression. The changes were correlated with clinical outcome at the 3-month follow-up examination. OBJECTIVES: To determine whether intraoperative dermatomal evoked potential latency asymmetry confirms nerve root compression and whether an improvement of latency asymmetry after decompression predicts a good clinical outcome. SUMMARY OF BACKGROUND DATA: Intraoperative dermatomal evoked potential has been proposed as a test to assess the adequacy of nerve root decompression. Initial reports suggested improvement of dermatomal evoked potential amplitude and latency after decompression. The clinical efficacy is controversial because of its technical difficulty and inherent variation. METHODS: Cervical recording was chosen to reduce the effects of anesthesia. The asymptomatic nerve root was used as a control. Quality of the tracings was determined by evoked potentials-to-noise amplitude ratio. Clinical outcome was based on patient's pain relief and satisfaction. RESULTS: Tracings of acceptable quality were obtained at baseline in 57.6% (19 of 33) of patients. A side-to-side latency asymmetry > 5% was defined as abnormal. Before decompression, 68.4% (13 of 19) of patients had an abnormal dermatomal evoked potential. After decompression, latency asymmetry returned to normal in every patient. Clinical outcome was good or excellent in 13 patients, fair in four patients, and poor in two patients. Dermatomal evoked potential latency improvements were not related to variation in clinical outcome. CONCLUSIONS: Intraoperative dermatomal evoked potential monitoring is technically demanding. Finding reproducible potentials is difficult. More research is necessary before general use of dermatomal evoked potentials for monitoring nerve root decompression.

Adult↗

Effects of decompressive craniectomy on regional cerebral blood flow in severe head trauma patients.

The effect of decompressive craniectomy on regional cerebral blood flow (rCBF) was investigated in five patients with severe head trauma who underwent decompressive craniectomy. Repeated rCBF studies using single photon emission computed tomography with 99mtechnetium-hexamethylpropyleneamine oxime observed that a hyperperfusion area (focal CBF increase) occurred in the decompressed brain within 24 hours after decompressive craniectomy. The hyperperfusion area in the decompressed brain enlarged and increased in severity by 1 week after surgery. However, it attenuated and disappeared by 1 month after surgery. The chronology of the hyperperfusion area corresponded to the change in the swelling of decompressed brain observed by x-ray computed tomography. Patient consciousness showed a significant and progressive improvement in the postoperative 1 month period. Decompressive craniectomy may cause a focal CBF increase in the decompressed brain related to the beneficial effect in patients with acute severe head trauma.

Adolescent↗

The effect of surgical decompression on neurologic outcome after lumbar fractures.

From 1980 until 1989, 69 patients with lumbar fractures resulting in incomplete paraparesis were admitted to the authors' medical center for treatment. Thirty had anterior vertebrectomy, including 18 who had posterior instrumentation and four who had anterior instrumentation. Twenty-two patients were treated with a posterolateral decompression and fusion, including four who also required an anterior decompression. Nineteen of the remaining 21 patients required posterior spine instrumentation and fusion only. The American Spinal Injury Association (ASIA) motor index score was determined for each patient pre- and postoperatively and used to compare these three treatment groups. Average follow-up period for the patients was 19 months. The improvement in ASIA motor score for all patients treated with decompression averaged 10 and similar improvement was obtained in those who were treated with posterior decompression (10.2 points). The average improvement in those who had vertebrectomy was 9.9 points. For those who had fusion without decompression, average improvement was 4.2 points. Comparing those patients who were surgically decompressed, either anteriorly or posteriorly, with those patients who only underwent fusion, the difference in neurologic improvement was statistically significant. Neurologic outcome after lumbar fractures is improved by surgical decompression. The neurologic outcome results were similar after anterior and posterior decompression.

Follow-Up Studies↗

The effect of early craniocervical decompression on functional outcome in neonates and young infants with myelodysplasia and symptomatic Chiari II malformations: results from a prospective series.

The indications for hindbrain decompression in neonates and young infants with spinal dysraphism who experience brain stem dysfunction in association with Chiari II malformations have remained controversial. This largely reflects the fact that the postoperative outcome in such patients has often been poor, which has supported the belief that much of the brain stem compromise in these patients is congenital and inherently irreversible. However, in a previous retrospective review of our operative results between 1975 and 1989, we noted that a significant component of the brain stem dysfunction in these children was an acquired phenomenon that potentially was reversible with prompt operative intervention. Accordingly, we hypothesized that with early craniocervical decompression, excellent functional outcome could be achieved in a majority of neonates and young infants with symptomatic Chiari II malformations. On the basis of this premise, we prospectively treated all such patients since 1989 with urgent brain stem decompression after other potential causes for brain stem dysfunction, such as progressive hydrocephalus, had been ruled out. All children underwent limited suboccipital craniectomies, cervical laminectomies extending beneath the inferior extent of the cerebellar tissue, and dural decompressions. The outcome in these patients has been favorable in comparison with previous studies. Ten of the 13 children treated according to this protocol recovered normal or nearly normal brain stem function shortly after decompression; 1 child had mild residual unilateral lower cranial nerve paresis. None of these children required a tracheostomy for ventilatory support, and only one required a temporary gastrostomy. The other three children all exhibited bilateral vocal cord paralysis and severe central hypoventilation by the time decompression was performed and failed to have any meaningful recovery of function. We conclude that early recognition of the symptoms of brain stem compromise in neonates and young infants with spinal dysraphism coupled with urgent evaluation and decompression are effective in producing prompt resolution of the brain stem dysfunction in most affected patients. Conversely, the prognosis for recovery is poor in children who exhibit bilateral vocal cord paralysis by the time of decompression.

Arnold-Chiari Malformation↗