[Individual learning curves with reference to endonasal micro-endoscopic pan-sinus operation]

BACKGROUND

We examined how surgeons in training will develop into experienced surgeons in sinus surgery by analysing their individual learning curve.

METHODS

In a retrospective study we evaluated complications in 818 surgical procedures (362 revisions = 44.3%) performed by four different surgeons.

RESULTS

We found a dural lesion in six cases (0.75%), opening of the periosteum of the orbit in 30 cases (3.7%), and control of bleeding from the anterior ethmoidal artery in 36 cases (4.4%). No lesions of the internal carotid artery or lacrimal duct system occurred. The complications were not distributed equally. We observed a three-phase learning process which we describe using the example of a traffic light: red with a high risk of complications, yellow with a minor one, and green for the experienced surgeon. The first phase consists of the first 20 procedures, yellow from the 20th to the 100th, and green for procedures performed thereafter.

CONCLUSIONS

Each inexperienced surgeon has to determine his position on the learning curve. He or she should be supervised accordingly.

Prevention of thermal tissue injury induced by the application of polymethylmethacrylate to the calvarium

The exothermic reaction produced during the polymerization of polymethylmethacrylate yields temperatures in excess of 180 degrees F (81.4 degrees C). At these elevated temperatures, significant bone and dural necrosis occurs. In an attempt to prevent thermal injury during craniofacial surgery, surgeons irrigate the polymerizing implant with cold saline, assuming that this will decrease both the absolute temperature elevation and the duration of the exothermic reaction, making the use of methylmethacrylate safe. Unfortunately, no experimental evidence exists to support this claim. To test the safety of methylmethacrylate during craniofacial surgery, we constructed an in vitro model that allowed us to measure directly the heat transferred from the methylmethacrylate to the underlying dura or bone during polymerization. In this model, the methylmethacrylate implants were 6 cm in diameter, but they varied in thickness. We hypothesized that methylmethacrylate could be safely applied up to a certain thickness, after which the temperature rise on the undersurface of the implant would no longer be controlled by any amount of cold saline irrigation, and thermal necrosis would occur. We found that without irrigation all implants produced temperatures in excess of 180 degrees F (81.4 degrees C) internally. This peak temperature lasted for approximately 45 seconds and then declined to a baseline temperature of 98 degrees F (36.3 degrees C) over 5 to 6 minutes. Upon irrigation of the implants with cold saline (4 degrees C), the level and duration of temperature elevation conducted to the underlying surface varied significantly on the basis of implant thickness. Implants smaller than 5 mm thick produced temperatures on the bone surface of 108 degrees F (41.8 degrees C) for 11 seconds. This temperature control was partially lost at 7 mm when the underlying surface reached a temperature of 134 degrees F (56.1 degrees C) for 15 seconds. Methylmethacrylate implants with a thickness greater than 7 mm produced temperatures of 145 degrees F (62.2 degrees C) for 22 seconds, indicating that the cold was insufficient to protect against thermal injury. Therefore, we conclude that polymethylmethacrylate can be applied safely to the skull if the implant is 6 mm thick or smaller. With polymethylmethacrylate thicker than this, the heat produced during polymerization cannot be controlled, and thermal necrosis to the underlying tissues is inevitable.

Craniosynostosis in babies: complications and management of 40 cases

Forty consecutive craniofacial cases in babies operated on in a district general hospital by a craniofacial team consisting of maxillofacial and neurosurgeons are reviewed with regard to diagnosis, surgical treatment, complications and outcome. Surgery achieved the release of craniosynostosis and the treatment protocol, and perioperative complications are discussed. Dural breaches occurred on four occasions with no postoperative sequelae. Blood transfusion was required in all cases with an average replacement of 36 percent estimated blood volume (EBV). No central nervous system complications occurred but in one case a brachial plexus haematoma resulted in a temporary neuropraxia to the shoulder. No major infections or deaths occurred in this series.

Cerebrospinal fluid pseudocyst after anterior stabilization for cervical spine injury treated by ventricular drainage: case report

The author describes postsurgical formation of a cerebrospinal fluid (CSF) pseudocyst after anterior decompression and stabilization for cervical spine injury. The CSF pseudocyst was caused by extensive lacerations to the spinal dura mater. A further contributory factor was a circulation blockage of CSF in the spinal canal, brought about by edema of the contused spinal cord. Ventricular drainage caused rapid collapse of the pseudocyst and its subsequent healing.

Herniation of the spinal cord 38 years after childhood trauma

We report an unusual post-traumatic spinal cord herniation, which became symptomatic 38 years after the trauma. A 44-year-old man presented with a 2-year history of increasing impotence, neuropathic bladder dysfunction and dissociated sensory loss below the level of T6. At the age of 6 years he had a severe blunt spinal injury with transient paraparesis. MRI revealed right lateral and ventral displacement of the spinal cord at the T5/6 level. The spinal cord was surgically exposed and found to herniate through a ventral defect of the arachnoid membrane and the dura mater. As there were no other events that could have precipitated spinal cord herniation the reported blunt trauma in childhood is the most likely cause for the spinal cord herniation in this patient.

[Puncture of the dura mater, diagnosis and treatment in obstetrics]

During the daily practice of Gynecoobstetrics there is a great relationship with anesthetic procedures. It is very important to know one of the most frequent complications of peridural blockade, as is accidental puncture of duramater. A review of this complication will be done, in order to help the physician to face this complication with an ample knowledgement, in order to be able to start opportune and adequate treatment.

[Lack of ossification of the skull after surgery for craniosynostosis. A study of risk factors apropos of 592 cases]

The Center for Craniofacial Anomalies of Necker-Enfants-Malades Hospital presents a retrospective study of the outcome of 592 patients who were operated for craniosynostosis between 1976 and 1991. The quality of ossification one year after operation is reported with a focus on influencing factors. The lack of ossification rate is 5% (30/592). Three parameters are identified as increasing the risk of poor osseous wound healing: local postoperative infection, forehead advancement especially when accomplished with resorbable osteosynthesis, and brachycephaly. On the contrary, repaired tears of the dura mater do not seem to pose a risk. Seventy five per cent of patients with local infection and 12.4% of forehead advancement presented a lack of ossification which is statistically significant (p < 0.001). Lack of ossification can compromise aesthetic and functional results. Decreasing postoperative infection and stable fixation may help to avoid it.

[Management of breach of the tegmen isolated or associated with cephalocele]

This is a retrospective report of 41 tegmen breaches observed in 2 different populations : 27 patients among a series of 252 cases of operated chronic otitis (6.7%) and 14 patients admitted for management of tegmen breach and dura mater involvement. The most frequent cause was chronic otitis (36 cases, including 6 due to iatrogenic causes); there were also 2 cases of petrus fracture, 2 cases of intracranial hypertension and 1 idiopathic case. Computed tomography revealed a bony breach in 97% of the cases. Encephalo-meningocele was associated in 11 cases (31%). In these cases, MRI confirmed the preoperative diagnosis. Treatment via the mastoid route allowed removal of the infectious process and via the suprapetrous route allowed closure of the breaches in the bone and dura mater as well as treatment of associated cephaloceles, except in case of major infection where the cephalocele was closed in a second operation.

Cervical dural puncture and lumbar extradural blood patch

The authors report the successful treatment of post-dural puncture headache, consequent to a cervical dural puncture, with a lumbar extradural blood patch. The increase in intracranial pressure generated by the injection of autologous blood in the extradural space seems to be the likely mechanism for the prompt relief of post-dural puncture headache. We conclude that extradural injection of autologous blood at the same level of the dural puncture may not be necessary.

Spinal anaesthesia in obstetrics

Spinal anaesthesia has been used since the 1800s but, due to a number of complications, the popularity of this technique has waxed and waned. In the 1950s, it was the most widely used method of anaesthesia and analgesia in obstetrics but it fell out of fashion with the arrival of the epidural technique which allowed a continuous method of delivering analgesia with relatively few complications. Hypotension and the high incidence of postdural puncture headaches were two reasons for the decline in the popularity of spinal anaesthesia in the young, otherwise healthy pregnant population. With the development of newer needles and bevel designs and methods whereby the incidence of hypotension can be minimized, spinal anaesthesia is making a reappearance in obstetrical anaesthesia spheres. The purpose of this article is to review the history, effects, technique, indications, contraindications and complications of this method of anesthesia as it applies to the obstetrical patient.

[Surgical treatment of craniosynostosis]

Craniosynostosis is the term that designates premature fusion of one or more cranial sutures that causes severe cranial deformities. The clinical features and the operative technique were introduced and the etiology and the key points for a successful operation were discussed in this paper.

Resolution of pachymeningeal enhancement following dural puncture and blood patch

We describe thickening and contrast enhancement of the intracranial pachymeninges, revealed by MRI in a patient with presumed low-pressure headache following dural puncture and a blood patch. The clinical and radiological abnormalities resolved within 2 weeks.