Selective spinal anesthesia for outpatient laparoscopy. IV: Population pharmacodynamic modelling

PURPOSE: To apply a population pharmacodynamic model to small-dose hypobaric spinal anesthesia for outpatient laparoscopy. METHODS: The level of spinal analgesia after spinal blockade with small-dose (20-25 mg) hypobaric lidocaine was assessed by means of pinprick in patients undergoing outpatient laparoscopy. In 57 patients, 385 measurements were available for analysis. We first modelled the data for each patient with a mixed-effects model described by Schnider (Model 1). The population mean parameters, inter-individual variance, and residual variance were estimated. Clinically important endpoints (time to reach T10 (onset), time to maximal level, duration and maximally attained level) of each patient were calculated based on the estimated time course of analgesia level for each patient. The model was used to predict the later data with respect to level of spinal analgesia of each patient from fits based on the observed data in the first 75 min. RESULTS: The mean +/- SD onset time was 8.3 +/- 1.9 min, time to maximal level was 20.8 +/- 5.3 min, duration of effect was 37.9 +/- 13.1 min, and mean maximal level was T5. There was a good correlation (R2 = 0.90) between the observed levels of analgesia and those predicted from the model. Data from the first 75 min predicted the later observed data for each patient moderately well (R2 = 0.38). CONCLUSION: A population pharmacodynamic model was applied to low-dose hypobaric lidocaine spinal anesthesia. Clinically important endpoints were determined and forecasting of later data with respect to level of spinal analgesia was attempted. Such an approach may be useful in the management of low-dose spinal anesthetic techniques in outpatients.     

Surgical correction of spinal deformities following spinal cord injury occurring in childhood

This article reports on the surgical treatment of 14 consecutive patients with paralytic spinal deformities secondary to spinal cord injury occurring in childhood. Eleven patients underwent a posterior spinal fusion and three patients underwent a combined anterior and posterior spinal arthrodesis. Luque rods were used in all but one patient. The spinal fusion extended to the sacrum in 10 patients. No patient developed postoperative wound infections or medical complications. Four patients (28.6%) who underwent initially a posterior spinal arthrodesis developed pseudarthrosis. This was treated successfully by a combined anterior and posterior spinal fusion in two patients. The remaining patients underwent a revision posterior spinal fusion with recurrence of the nonunion in one patient. A combined anterior and posterior spinal arthrodesis could be considered the treatment of choice for patients with severe deformities who can tolerate anterior surgery. If pseudarthrosis develops following posterior spinal fusion, this can be best treated by a combined anterior and posterior revision procedure with instrumentation.     

The influence of lumbosacral cerebrospinal fluid volume on extent and duration of hyperbaric bupivacaine spinal anesthesia: a comparison between seated and lateral decubitus injection positions

We designed the present study to examine the influence of lumbosacral cerebrospinal fluid (CSF) volume on the spread and duration of hyperbaric bupivacaine spinal anesthesia when the injection is made with the patient in the lateral position compared with that when the patient is in a seated position. Seventy-four patients undergoing peripheral orthopedic or urogenital surgery with spinal block were enrolled. Lumbosacral CSF volumes were calculated from axial magnetic resonance images. Patients were randomly assigned to 1 of 2 groups: the lateral (L) and seated (S) groups (n = 37 each). Spinal anesthesia (3 mL hyperbaric 0.5% bupivacaine) was administered using a 25-gauge pencil-type needle with the needle aperture directed cephalad and the patient in the lateral decubitus position with the non-operated side up (L group) or with the patient in a seated position (S group). Patients were turned supine immediately after spinal injection (L group) or after remaining seated for 2 min (S group). Statistical correlation coefficients (rho) were assessed using Spearman's rank correlation. There were negative correlations between CSF volume and peak sensory block level in both the L (rho = -0.69, P < 0.0001) and S groups (rho = -0.68, P < 0.0001). In the S group, but not in the L group, CSF volume significantly correlated with onset time of peak sensory block level (rho = -0.48, P = 0.004), and time required for regression to L1-4 (P < 0.05-0.01). We conclude that CSF volume influences the spread of spinal anesthesia with hyperbaric bupivacaine regardless of patient position when the spinal injection is made. CSF volume influenced the duration of spinal sensory anesthesia when the injection was made with the patient in a seated position, but not in the lateral position. IMPLICATIONS: Patient position during the spinal injection does not alter the influence of cerebrospinal fluid (CSF) volume on the spread of hyperbaric bupivacaine spinal anesthesia. However, CSF volume influences the duration of spinal sensory anesthesia when the injection is made with the patient in a seated position, but not in the lateral position.     

Identification of the lumbar intervertebral level using ultrasound imaging in a post-laminectomy patient

A spinal block was performed in a post-laminectomy patient, using both ultrasound imaging and X-ray imaging. Ultrasound imaging clearly identified the L3/4 intervertebral level, the spinal canal, the corpus vertebrae, and the dura mater. Using ultrasound imaging, we measured the distance from the skin surface to the dura mater (39 mm). A 25-G needle for the spinal block was accurately advanced into the spinal canal with the use of X-ray imaging (43 mm from the skin to the subarachnoid space). We report here that ultrasound imaging was useful for performing a spinal block in a post-laminectomy patient in whom there was anatomical change around the spine.     

Use of continuous positive airway pressure during spinal anaesthesia in a patient with severe chronic obstructive pulmonary disease

We report the case of a patient with severe chronic obstructive pulmonary disease who underwent local resection of a carcinoma of the rectum under spinal anaesthesia. Although the patient was keen to avoid general anaesthesia and to have the operation under a spinal anaesthetic, pre-operative assessment showed that he could not lie flat. As the surgical procedure required the patient to be in the lithotomy position, ideally with a head-down tilt, it was hoped that continuous positive airway pressure with a facemask during spinal anaesthesia might help him to tolerate the position comfortably. Continuous positive airway pressure at 7.5 cmH(2)O was successfully used to facilitate breathing during surgery under spinal anaesthesia. A combination of regional anaesthesia and continuous positive airway pressure via a facemask is easy to use and may be a useful option in the management of these challenging patients.     

A rare intraosseous arteriovenous malformation of the spine

The authors report the case of a patient with an intraosseous spinal arteriovenous malformation (AVM) presenting as an epidural mass lesion that was causing spinal cord compression. The 59-year-old woman had bilateral numbness, weakness, and hyperreflexia of both legs. Magnetic resonance imaging revealed intermediate T1 signal and hyperintense T2 signal involving the right transverse process, bilateral pedicles, and T-5 spinous process; the lesion's epidural extension was causing severe canal compromise and cord displacement. Coil embolization was performed, and the patient underwent resection, after which preoperative symptoms improved. Histopathological analysis revealed a benign vascular proliferation consistent with an intraosseous spinal AVM. On review of the literature, the authors found this case to be the second intraosseous spinal AVM, and the first in a patient whose clinical presentation was consistent with that of a mass lesion of the bone.     

Isolated thoracolumbar and lumbar hyperlordosis in a patient with cerebral palsy

A severe isolated thoracolumbar and lumbar hyperlordosis spinal deformity occurring in a patient with cerebral palsy is rare and has not been reported before. The authors describe the presentation, operative considerations, and treatment of patients with this unusual hyperlordotic spinal deformity, particularly those with cerebral palsy. A multiple-stage surgical reconstruction was required to correct this complex spinal deformity. The patient underwent bilateral femoral extension osteotomies along with spinal extensor myotomies to ensure proper prone positioning for his anticipated spinal surgery. Then he had staged anterior releases and spinal fusion from T8 to the sacrum followed by 2 weeks of "90-90" femoral skeletal traction. Finally, a posterior spinal fusion with instrumentation from T2 to the pelvis definitively corrected his deformity. The patient responded well to surgical intervention without complications and continues to have stable correction of his hyperlordosis deformity 2 years after surgery. Severe lordotic sagittal plane spinal deformities can be treated with anterior and posterior spinal fusion and instrumentation with intervening traction in the properly selected and prepared patient who has cerebral palsy.     

Brown-Séquard syndrome following removal of a cerebrospinal fluid drainage catheter after thoracic aortic surgery

Neurological deficit remains a devastating complication of thoracic aortic surgery despite advances in methods to protect the spinal cord from ischemia. Various techniques have been used, including the combination of cerebrospinal fluid (CSF) drainage and distal aortic perfusion to decrease the incidence of postoperative neurological deficit. These deficits are usually bilateral and result in paraplegia. In this case report we present a patient with Type B aortic dissection and thoracoabdominal aortic aneurysm repair with insertion of a lumbar CSF drainage catheter. Postoperatively, the patient developed unilateral neurological features consistent with Brown-Séquard syndrome after removal of the CSF catheter. The lumbar cerebrospinal fluid catheter was reinserted and the CSF was drained. Medullary T6-7 signal abnormalities were seen on spinal cord magnetic resonance imaging, and we suggest that the spinal cord suffered a direct injury during catheter removal. The patient had an uneventful recovery. IMPLICATIONS: We describe a patient who developed unilateral neurologic features suggestive of Brown-Sequard syndrome following removal of a cerebrospinal fluid catheter after thoracic aortic surgery. We suggest that the spinal cord was injured during catheter removal. The catheter was reinserted and the patient had a full neurologic recovery.     

Spinal anaesthesia for Caesarean section in a patient with a cervical arteriovenous malformation

Purpose

Arteriovenous malformations (AVM) of the spinal cord are rare. We report the successful management of a patient with a cervical spinal cord AVM undergoing Caesarean section delivery, using a spinal anaesthetic.

Clinical features

Based on previous radiological investigations, the patient was known to have an AVM at the third cervical level of her spinal cord. After application of monitors and intravenous administration of 1 L normal saline, a 25 g Whitacre needle was inserted into the subarachnoid space at the L_3–4 interspace. Spinal anaesthesia was established with a solution consisting of hyperbaric spinal bupivacaine 12 mg, fentanyl 12.5 μg and epidural morphine 0.25 mg. There was no neurological deficit during hospital stay or after discharge.

Conclusion

The safe outcome of spinal anaesthesia for our patient is encouraging. The presence of spinal cord AVM at the cervical region is not an absolute contraindication to spinal anaesthesia.     

Cervicothoracolumbar pneumorachis. Case report and review of the literature

BACKGROUND: Pneumorachis is a very rare entity to occur after a major trauma. It is even rarer when its occurrence is not associated with injuries in the skull base, chest, abdomen, pelvis, or spine. Pneumorachis extending through the entire spinal canal has never been reported. CASE DESCRIPTION: We report a case of traumatic air penetration into the spinal canal in a patient, involved in a road traffic accident, who had no apparent major bone and soft tissue injuries. The patient was conscious (Glasgow Coma Scale score of 15/15) upon admission. A cervical lateral x-ray taken the day after admission showed some air in the spinal canal. A subsequent computed tomography with reconstruction disclosed some subdural air extending from the cervical region to the lumbar region. The patient was successfully treated conservatively. The pathogenesis and rarity of this pathology are discussed along with the review of relevant literature. CONCLUSION: Any patient with spinal pneumorachis should be actively investigated to determine if a possible air fistula, which might increase causing spinal cord compression, is present. If a source is not found, a skull base fracture should be suspected.     

The minimum effective dose of 0.5% hyperbaric spinal bupivacaine for cesarean section

BACKGROUND: The aim of this prospective, blind study was to determine the minimum effective dose of hyperbaric bupivacaine required for cesarean section. METHODS: With Ethical Committee approval and written consent, 24 healthy women undergoing elective cesarean section received a combined spinal epidural anesthesia. We sought to determine the minimum effective dose of spinal bupivacaine using a staircase method. In each patient an arbitrary dose of 0.5% hyperbaric bupivacaine in relation to patient height was used. The initial dose was 0.075 mg/cm height, while the outcome of each patient's response determined the dose for the subsequent patient. When successful spinal block (sensory level = or < T4 with complete motor blockade) was achieved within 20 min from spinal injection, the dose of spinal bupivacaine for the next patient was decreased by 0.01 mg/cm height. Conversely, when successful spinal block was not observed, the dose of spinal bupivacaine for the next patient was increased by 0.01 mg/cm height. Sensory and motor blocks were evaluated every 5 min by an independent, blinded observer. If successful spinal block was not achieved within the designed period, a 5-8 ml epidural bolus of 2% lidocaine was given to achieve adequate surgical anesthesia. RESULTS: No complications were reported during the study, and all women delivered their baby uneventfully (APGAR scores 5 min after delivery ranged from 9 to 10) within 5 min from uterus incision. The duration of surgical procedure ranged from 30 to 48 minutes. The dose of hyperbaric bupivacaine providing adequate surgical anesthesia within 20 min from spinal injection in 50% of subjects was 0.036 mg/cm height (95% confidence intervals: 0.031-0.041 mg/cm height). The ED95 calculated from the probit transformation to provide effective spinal anesthesia for cesarean section was 0.06 mg/cm height. CONCLUSIONS: This prospective, blind study demonstrated that a dose as low as 0.06 mg/cm height represents the dose of intrathecal bupivacaine providing effective spinal block in 95% of women undergoing elective cesarean section.     

Cardiac arrest after spinal anesthesia in a patient with neurally mediated syncope

We present the case of cardiac arrest in a patient with neurally mediated syncope (NMS). A 66-year-old male patient was scheduled to undergo right inguinal hernioplasty. He had a history of syncope, which occurred a few times a year in childhood and once a year recently. One minute after the second spinal injection, cardiac arrest (asystole) developed. Sinus rhythm was restored by cardiac massage and intravenous administration of atropine and ephedrine. The operation was cancelled. The patient was diagnosed as NMS by a cardiologist. Four months later, right inguinal hernioplasty was performed, uneventfully, under general anesthesia. High sympathetic blockade due to spinal anesthesia and transient withdrawal of sympathetic tone and increase in vagal discharge due to NMS could be the main causes of the cardiac arrest. If the patient has any possibility of NMS, anesthesiologists should consider the possibility of cardiac arrest after spinal anesthesia.     

Obliteration of a tentorial dural arteriovenous fistula causing spinal cord myelopathy using the cranio-orbito zygomatic approach

BACKGROUND: Intracranial dural arteriovenous fistulas account for 10 to 15% of all intracranial arteriovenous malformations. Tentorial dural arteriovenous fistulas with spinal medullary venous drainage causing spinal cord myelopathy are very rare, but have been previously described. We describe a case using a cranio-orbito zygomatic approach with intraoperative angiography for the surgical treatment of a tentorial artery dural arteriovenous fistula causing spinal cord myelopathy. CASE PRESENTATION: A 42-year-old male presented complaining of a 1-year history of incoordination and dizziness and a 2-month history of progressive myelopathy with bowel and bladder incontinence. The patient had magnetic resonance imaging (MRI) performed along with cerebral and spinal angiography that revealed a right tentorial artery dural arteriovenous fistula with spinal medullary venous involvement down to T11. Angiographic embolization was attempted, but selective catheterization was unsuccessful. The patient underwent a cranio-orbito zygomatic approach with obliteration of the dural arteriovenous fistula. An intraoperative angiogram confirmed complete obliteration of the dural arteriovenous fistula. CONCLUSION: Intracranial dural arteriovenous fistulas are a rare cause of spinal cord myelopathy. When a patient presents with suspicion of spinal dural fistula and negative spinal angiography, an intracranial origin should be suspected and a cerebral angiogram performed. Skull base approaches along with intraoperative angiography provide an alternative modality for obliteration of the dural arteriovenous fistula nidus, thereby eliminating the venous congestion and hence the spinal cord ischemia.     

Management of transperitoneal gunshot wounds of the spine.

To evaluate the results of a conservative approach to gunshot wounds of the spine with a transperitoneal trajectory, we analyzed our 4-year experience with 21 patients. The management protocol consisted of standard treatment of the intra-abdominal injuries, vigorous irrigation of the missile track, and a 48-hour course of antibiotic therapy. The lumbar spine was involved in 14 patients (67%) and the thoracic spine was injured in seven (33%). Eleven patients (52%) were paraplegic on admission and ten patients (48%) had a fixed partial neurologic deficit. One patient with an ISS of 75 died intraoperatively from exsanguination (mortality, 5%). Early morbidity correlated with ISS greater than 40 and spinal AIS greater than 3. Late nonneurologic morbidity was independent of ISS and spinal AIS. One patient required reoperation for a retroperitoneal abscess secondary to a leak from a repaired ureter. Another patient had a retroperitoneal collection on a CT scan which resolved spontaneously. There were no spinal or paraspinal infectious complications in the presence (five cases) or absence of a colonic injury. No change in neurologic status was observed in any patient during a mean follow-up period of 3 months. This preliminary experience suggests that a conservative approach consisting of irrigation of the missile track and short-term antibiotic therapy without laminectomy or removal of fragments from the spinal canal yields optimal results without increasing infectious complications of the spine.     

A case of high-aged idiopathic spinal cord herniation from dural defect

Idiopathic spinal cord herniation was assumed to be a rare disease. However, the incidence of discovering this condition appears to have been increasing recently with advances in neuroradiological diagnosis using magnetic resonance imaging (MRI) and computed tomographic myelogram (CTM). We present herein an operated case of high-aged idiopathic spinal cord herniation. A 71-year-old female presented with spastic paresis of the right lower limb and sensory disturbance of pain and temperature below the level of the left Th4 dermatome, consistent with Brown-Séquard syndrome. MRI and CTM revealed right ventral displacement of the spinal cord and dilatation of the dorsal subarachnoid space at Th2/3. Laminectomy of Th1-3 was performed, herniated spinal cord was untethered and repositioned, and the dural defect was sealed with GORE-TEX dura substitute. Postoperative MRI revealed normal location of the spinal cord and neurological state improved slightly. The patient was discharged 1 month after the operation. Among many cases of spinal cord herniations, this is considered to be a rare case of idiopathic spinal cord herniation in an elderly patient.     

Subarachnoid hemorrhage caused by a rupture of a spinal arteriovenous malformation

The authors report on a patient presenting with subarachnoid hemorrhage that was caused by a rupture of an spinal combined arteriovenous malformation at cervicothoracic junction. The patient was a 30-year-old female, who had exhibited an abrupt onset of severe low neck and occipital pain with radiation into shoulders and vomiting. Neurological examination revealed severe meningism without motor or sensory deficit. Digital subtraction angiography did not demonstrate any intracranial source of bleeding, whereas spinal angiography revealed a spinal arteriovenous malformation at cervicothoracic junction. Endovascular treatment of the malformation was considered for this patient. Occipital and neck pain with radiation into schoulders and severe meningism are clues pointing to a spinal origin of the haemorrhage.     

Extensive spinal cord infarction after posterior fossa surgery in the sitting position: case report

OBJECTIVE AND IMPORTANCE: Spinal cord injury is a rare complication of neurosurgery performed with the patient in the sitting position. Previous reports showed that the level of injury is usually located at or near the C5 segmental spinal level, and the term midcervical quadriplegia has been proposed. Extensive spinal cord and lower brainstem infarction also can occur after posterior fossa surgery performed with the patient in the sitting position. CLINICAL PRESENTATION: We describe a 45-year-old woman who was operated on in the sitting position because of a fourth ventricular pilocytic astrocytoma. After surgery, the patient experienced quadriplegia. INTERVENTION: T2-weighted magnetic resonance imaging scans revealed a long, hyperintense area within the cervicothoracic spinal cord that was extended to the lower pons and was consistent with infarction. There was no evidence of previous spine disease. The patient died 6 weeks later of respiratory failure. CONCLUSION: We speculate that alteration of spinal cord blood flow by stretching of the cervical spinal cord and spinal epidural venous engorgement might have caused this devastating complication.     

Reversal of high spinal anesthesia with cerebrospinal lavage after inadvertent intrathecal injection of local anesthetic in an obstetric patient

Purpose

High or total spinal anesthesia commonly results from accidental placement of an epidural catheter in the intrathecal space with subsequent injection of excessive volumes of local anesthetic. Cerebrospinal lavage has been shown to be effective at reversing the effects of high/total spinal anesthesia but is rarely considered in obstetric cases. Here, we describe the use of cerebrospinal lavage to prevent potential complications from high/total spinal anesthesia after unintentional placement of an intrathecal catheter in a labouring obstetric patient.

Clinical features

A 34-yr-old female presented to the labour and delivery unit in active labour. Epidural anesthesia was initiated, and after the first bolus dose, the patient experienced lower extremity motor block and shortness of breath. A high spinal was confirmed, and cerebrospinal lavage was performed. In total, 40 mL of cerebrospinal fluid (CSF) were exchanged for an equal volume of normal saline. The patient’s breathing difficulties and motor block resolved quickly, and a new epidural catheter was placed after removal of the spinal catheter. Pain control was effective, and the patient delivered a healthy baby.

Conclusion

We show that exchange of CSF for normal saline can be used successfully to manage a high spinal in an obstetric patient. Our results suggest that CSF lavage could potentially be an important and helpful adjunct to the conventional supportive management of obstetric patients in the event of inadvertent high or total spinal anesthesia.     

Perioperative intracranial hemorrhage in achondroplasia: a case report

We report a case of a 35-year-old man with achondroplasia who previously had thoracolumbar decompressive laminectomies, who developed recurrence of spinal stenosis at the thoracolumbar junction. The patient underwent standard repeat thoracolumbar decompression, removal of a disc, and spinal fusion with instrumentation in the prone position. Postoperatively the patient was confused. Computed tomography (CT) revealed hemorrhages in both cerebellar hemispheres with surrounding edema and mild mass effect. These were interpreted as venous hemorrhages. Conservative therapy was successful. This is the first case report of perioperative venous intracranial hemorrhage in the context of spinal surgery for achondroplasia. Distinctive anatomic characteristics of achondroplasia, combined with several potentially modifiable aspects of his management, may have predisposed the patient to this complication.     

Free vascularized bone graft in spinal surgery: indications and outcome in eight cases

In selected spinal deformities the use of a vascularized graft to establish fusion may be considered: compared to a non-vascularized graft it has superior mechanical properties, resulting in greater graft strength and stiffness, and greater effectiveness in facilitating union. Eight patients with a progressive spinal deformity (four cases) and malignancy (four cases) were treated with resection and/or correction and stabilization. To facilitate (multi)level fusion vascularized fibular grafts were used in two cervical and two thoracolumbar deformities. Fibular (two cases) or iliac grafts (two cases) were used in four cases of spinal reconstruction after vertebrectomy for malignancy. In all patients complete incorporation of the graft was obtained within 5 weeks to 8 months postoperatively. Complications occurred in three cases: one patient had a transient laryngeal edema and laryngeal nerve palsy. Another patient had a non-fatal deep vein thrombosis with pulmonary embolisms, successfully treated with anticoagulants. A third patient developed a lung infection and subsequently a deep infection around the dorsal instrumentation; after hardware removal the infection was controlled. At the latest follow-up (mean 30 months, range 24– 48 months) six out of eight patients are alive. One patient died 2.5 years after the intervention due to widespread metastases, while another patient died in the postoperative period due to unknown reasons. Vascularized bone graft in spinal surgery facilitates primary mechanical stability and rapid fusion, and it has higher resistance to infection. The variety of applications of a vascularized graft may extend the range of indications for the use of grafts in spinal surgery. Received: 14 October 1998 Revised: 13 February 1999 Accepted: 9 March 1999