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PubMed1985

The role of lumbar puncture in the evaluation of dementia: the University of Pittsburgh Study.

In a retrospective study of 80 patients over 55 years old, the efficacy of lumbar puncture in evaluating elderly demented patients was examined. Despite a cost of $381 per procedure, in addition to cerebrospinal fluid (CSF) evaluation, no diagnosis was made on the basis of the information obtained in any of the patients (53 per cent) who underwent lumbar puncture. The only abnormalities found were 11 cases of nonspecific elevations in CSF protein and one case of abnormal cellularity not related to bacterial infection. An additional 422 cases of dementia from other series were reviewed, and only four patients were found whose diagnosis could have been made by lumbar puncture--one patient had neurosyphilis, and the other three were postencephalitic. In addition, the literature on complications of lumbar puncture was reviewed. There were no serious complications of lumbar puncture in the present study. The authors concluded that although it is low-risk, lumbar puncture cannot currently be recommended for routine use in the evaluation of elderly demented patients, but should be used in evaluating demented patients under 55 years of age, patients with rapid onset or progression of dementia, patients with syphilis serology in suspected cases of viral encephalitis, and patients with signs and symptoms of fungal meningitis.

Age Factors↗
PubMed2000

Randomised controlled trial of atraumatic versus standard needles for diagnostic lumbar puncture.

OBJECTIVE: To compare the ease of use of atraumatic needles with standard needles for diagnostic lumbar puncture and the incidence of headache after their use. DESIGN: Double blind, randomised controlled trial. SETTING: Investigation ward of a neurology unit in a university hospital. PARTICIPANTS: 116 patients requiring elective diagnostic lumbar puncture. INTERVENTIONS: Standardised protocol for lumbar puncture with 20 gauge atraumatic or standard needles. OUTCOME MEASURES: The primary end point was intention to treat analysis of incidence of moderate to severe headache, assessed at one week by telephone interview. Secondary end points were incidence of headache at one week analysed by needle type, ease of use by operator according to a visual analogue scale, incidence of backache, and failure rate of puncture. RESULTS: Valid outcome data were available for 97 of 101 patients randomised. Baseline characteristics were matched except for higher body mass index in the standard needle group. By an intention to treat analysis the absolute risk of moderate to severe headache with atraumatic needles was reduced by 26% (95% confidence interval 6% to 45%) compared with standard needles, but there was a non-significantly greater absolute risk of multiple attempts at lumbar puncture (14%, -4% to 32%). Higher body mass index was associated with an increased failure rate with atraumatic needles, but the reduced incidence of headache was maintained. The need for medical interventions was reduced by 20% (1% to 40%). CONCLUSIONS: Atraumatic needles significantly reduced the incidence of moderate to severe headache and the need for medical interventions after diagnostic lumbar punctures, but they were associated with a higher failure rate than standard needles.

Adult↗
PubMed2004

Dura-arachnoid lesions produced by 22 gauge Quincke spinal needles during a lumbar puncture.

AIMS: The dural and arachnoid hole caused by lumbar puncture needles is a determining factor in triggering headaches. The aim of this study is to assess the dimensions and morphological features of the dura mater and arachnoids when they are punctured by a 22 gauge Quincke needle having its bevel either in the parallel or in the transverse position. METHODS: Fifty punctures were made with 22 gauge Quincke needles in the dural sac of four fresh cadavers using an "in vitro" model especially designed for this purpose. The punctures were performed by needles with bevels parallel or perpendicular to the spinal axis and studied under scanning electron microscopy. RESULTS: Thirty five of the 50 punctures done by Quincke needles (19 in the external surface and 16 in the internal) were used for evaluation. When the needle was inserted with its bevel parallel to the axis of the dural sac (17 of 35), the size of the dura-arachnoid lesion was 0.032 mm(2) in the epidural surface and 0.037 mm(2) in the subarachnoid surface of the dural sac. When the needle's bevel was perpendicular to the axis (18 of 35) the measurement of the lesion size was 0.042 mm(2) for the external surface and 0.033 mm(2) for the internal. There were no statistical significant differences between these results. CONCLUSIONS: It is believed that the reported lower frequency of postdural puncture headache when the needle is inserted parallel to the cord axis should be explained by some other factors besides the size of the dura-arachnoid injury.

Arachnoid↗
PubMed1993

Early and short-term complications after US-guided puncture of gynecologic lesions: evaluation after 1,000 consecutive cases.

PURPOSE: To ascertain the complication rate associated with ultrasound (US)-guided puncture of gynecologic lesions. MATERIALS AND METHODS: Between 1986 and 1992, 878 transabdominal and 122 transvaginal US-guided punctures of gynecologic lesions were performed in 893 patients. Most of the procedures were performed in adnexal cysts (n = 838); the rest, in solid tumors (n = 66), mixed tumors (n = 56), or lymphoceles, abscesses, or fluid collections (n = 40). No anesthesia or antibiotic prophylaxis was routinely used. RESULTS: No life-threatening complication was recorded. Early complications (defined as complications that occurred within 24 hours after puncture) were recorded in 31 patients and consisted mainly of transient vagal symptoms or pain. Short-term complications (within 5 days after puncture) were recorded in 10 patients, six of whom required surgery. CONCLUSION: US-guided puncture of gynecologic lesions is safe in selected patients. Complication rates depend on the type of lesion and are very high in dermoid cysts, which should not be punctured, and extremely low in serous cysts, solid tumors, and mixed tumors.

Abdominal Pain↗
PubMed2002

Local anesthesia with EMLA cream for maxillary sinus puncture.

Maxillary sinus puncture is traditionally carried out through the lateral wall of the inferior nasal meatus under local anesthesia. One problem with it is that the insertion of a cotton-tipped applicator soaked in local anesthetic is painful. Patients also dislike waiting for the anesthetic effect with the metallic applicators in the nose. In this study, we present a new, well-tolerated method of topical anesthesia for maxillary sinus puncture via the inferior meatus of the nose. Twenty adult patients with maxillary sinus infection who were undergoing bilateral maxillary sinus puncture were studied. One side of each patient's nose was anesthetized with a cotton-tipped applicator moistened with a lidocaine-adrenaline solution (LA), and the other side was anesthetized with EMLA cream instilled with a suction needle and syringe; the sides were chosen randomly. The mean "application of anesthesia" pain score on a 100-mm visual analog scale was 39.2 for the LA side and 9.1 for the EMLA side (p < .01). The anesthesia required for puncture was reached more quickly on the EMLA side than on the LA side (p = .02). The mean puncture pain score was 25.1 with LA and 8.6 with EMLA (p = .01). Fourteen patients out of the 20 (70%) found EMLA more tolerable, 3 patients (15%) found no difference, and 3 patients (15%) preferred LA (p < .01). We conclude that EMLA is better-tolerated and quicker-acting than LA for local anesthesia in maxillary sinus puncture.

Adult↗
PubMed2006

The yield of lumbar puncture to exclude nosocomial meningitis as aetiology for mental status changes in the medical intensive care unit.

We aimed to evaluate the diagnostic value of lumbar puncture in excluding nosocomial meningitis as the cause of mental status changes in medical intensive care unit patients. We retrospectively reviewed the records of all patients admitted to the medical intensive care unit at our institution over a four-year period who had a lumbar puncture performed during their stay. Patients with central nervous system devices were excluded. During the study period 63 lumbar punctures were performed, 31 to exclude nosocomial meningitis. Of these 31 patients, 25 (80.6%) received antimicrobials during hospitalization before performance of lumbar puncture. In one patient with human immunodeficiency virus (HIV) infection, Gram stain demonstrated yeast; in the remainder, Gram stain was negative. Cultures were negative for pathogenic bacteria in all 30 of these patients (overall yield: 0%, 95% CI: 0-10.0%). Five patients (16.1%) had a cerebrospinal fluid leucocytosis (>10 leukocytes/mm3); of these, all had received prior antibiotics, two had positive cryptococcal antigen results, and three had central nervous system infection suspected clinically without an evident alternative diagnosis. In no non-HIV subject did lumbar puncture alter management. Lumbar puncture performed in the medical intensive care unit to exclude nosocomial meningitis as the cause of mental status changes has a low yield and rarely changes management. These findings should not be generalized to patients who have sustained head trauma, have undergone neurosurgical procedures, or may be immunosuppressed.

Adult↗
PubMed2001

Delay of the diagnostic lumbar puncture and intrathecal chemotherapy in children with acute lymphoblastic leukemia who undergo routine corticosteroid testing: Tokyo Children's Cancer Study Group study L89-12.

PURPOSE: To determine the effects of eliminating initial lumbar punctures in 418 consecutively treated children with acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: Patients were enrolled onto a trial conducted in central Japan between 1989 and 1992. Treatment consisted of standard four-drug induction therapy followed by a risk-based intensification phase, reinduction therapy, late intensification, and remission maintenance therapy (total of 104 weeks). The initial lumbar puncture, with an intrathecal injection of chemotherapy, was performed after 1 week of prednisolone sensitivity testing (day 8). End points included response to prednisolone, CNS status at the time of the day 8 lumbar puncture, subsequent adverse events in CNS and bone marrow, and event-free survival (EFS). RESULTS: The remission induction rate was 93.1% with a 6-year EFS rate (+/- SE) of 68.7% +/- 2.4%, which is similar to historical results for patients who received their diagnostic lumbar puncture and first instillation of intrathecal chemotherapy on day 0. Overall, 84.5% of the patients had good responses to prednisolone, whereas 15.5% had poor responses. Clinical outcome was strikingly better for the good responders (6-year EFS, 74.1% +/- 2.5% compared with 40.1% +/- 6.4% for patients with poor responses), suggesting that omission of intrathecal chemotherapy did not alter the predictive value of drug sensitivity testing. Eighteen patients experienced CNS relapse as their first adverse event (cumulative risk, 5.1%; 95% confidence interval, 2.7% to 7.4%), coincident with reports from groups using conventional strategies of CNS clinical management. Bleeding into the CSF at the time of the day 8 lumbar puncture was apparent in 29 cases (8.1%), but leukemic blasts were identified in only two. CONCLUSION: Delay of the initial lumbar puncture and intrathecal injection of chemotherapy seems to be feasible in children with ALL. Further controlled evaluations are needed to establish the validity of this conclusion.

Adolescent↗
PubMed2005

Epidural injection of lidocaine reduces the response to dural puncture accompanying spinal needle insertion when performing combined spinal-epidural anesthesia.

During placement of needles for combined spinal-epidural anesthesia (CSEA), patients may experience pain, pressure, paresthesia, or discomfort during skin and deeper injection of local anesthetic, needle impingement on periosteum, dural puncture by the spinal needle, and insertion of the epidural catheter. We investigated the incidence of perception of and spontaneous verbal and motor responses to insertion of a spinal needle through the dura mater and pia mater and the effect of injecting lidocaine into the epidural space through the epidural needle before inserting the spinal needle through the meninges. Forty-three patients presenting for elective cesarean delivery under CSEA were studied. After localization of the epidural space using loss of resistance to air using a 17-gauge Tuohy needle, either 3 mL preservative free normal saline or 3 mL lidocaine 2% plus epinephrine 1:200,000 was injected through the Tuohy needle. "Needle through needle" dural puncture was performed 1 min later using a 27-gauge Whitacre pencil-point needle. At the moment of dural puncture, 2 (9%) parturients given lidocaine and 17 (81%) parturients given saline (P < 0.005) responded to dural puncture by spontaneously moving (33%), spontaneously vocalizing (62%), or, in response to direct questioning, by acknowledging (76%) having perceived sensation during thecal penetration. This study reveals that dural puncture by a Whitacre 27-gauge pencil-point needle inserted through a Tuohy epidural needle sited using loss of resistance to air causes involuntary movement, spontaneous vocalization, or is perceived by the majority of patients presenting for cesarean delivery under CSEA and that lidocaine injected into the epidural space before dural puncture largely eliminates these responses and sensations.

Adult↗
PubMed2003

Cerebrospinal fluid leakage after lumbar puncture in neonates: incidence and sonographic appearance.

OBJECTIVE: The purpose of this article is to review the incidence and sonographic appearance of cerebrospinal fluid leakage after lumbar puncture in the neonatal period. Thirty-three neonates underwent spinal sonography after diagnostic lumbar puncture. A total of 21 of these patients showed cerebrospinal fluid leakage into the epidural space extending from the level of the cauda equina to the lumbar (n = 9), the thoracic (n = 8), or the cervical (n = 4) region. In eight patients, the subarachnoid space was markedly compressed by the epidural fluid collection. CONCLUSION: Cerebrospinal fluid leakage into the epidural space is a frequent complication of lumbar puncture in neonates and has a characteristic appearance on sonograms. Leakage after lumbar puncture must be differentiated from cerebrospinal fluid leakage due to perinatal meningeal injury. If cerebrospinal fluid leakage at the puncture site compresses the subarachnoid space, sonography assists in the performance of subsequent lumbar puncture.

Cerebrospinal Fluid↗
PubMed2000

[Bed rest after lumbar puncture: a nation-wide survey in Austria].

BACKGROUND: Recommendations in medical textbooks concerning bed rest after lumbar puncture to prevent postpunctional headache vary between immediate mobilisation and 24 hours bed rest. AIM OF THE STUDY: The aim of the study was to evaluate the current practice in neurological departments. METHODS: We contacted all neurological departments in Austria by fax and asked about standards concerning bed rest after lumbar puncture and about the number of punctures per month. RESULTS: 28 out of 32 departments replied (88%). Fifty percent (n = 14) of the departments recommend 24 hours bed rest after lumbar puncture, recommendations of the other departments vary between immediate mobilisation (one department) and 16 hours bed rest. CONCLUSION: Current practice concerning bed rest after lumbar puncture varies widely in Austria and most patients are confined to bed for several hours. Even though there is evidence that bed rest does not prevent post lumbar puncture headache, there is so far no systematic review published in the medical literature.

Austria↗
PubMed2001

Does bed rest after cervical or lumbar puncture prevent headache? A systematic review and meta-analysis.

BACKGROUND: Headache after cervical or lumbar puncture has long been attributed to early mobilization; however, there is little evidence for this. We performed a systematic literature review and meta-analysis of randomized controlled trials to assess whether longer bed rest is better than immediate mobilization or short bed rest in preventing headache. METHODS: We searched EMBASE (1988 to March 2001), MEDLINE (1966 to May 2001), Pascal Biomed (1996 to February 2001), Current Contents (1997 to September 1999), PsycINFO (1966 to May 2001), the Cochrane Controlled Trial Register (last search May 15, 2001), textbooks and references of the papers selected. Studies were eligible if patients underwent cervical or lumbar puncture for any reason and were randomly assigned to either a long or a short period of bed rest. Data were abstracted independently by 2 investigators to a predefined form. RESULTS: We found 16 randomized controlled trials involving 1083 patients assigned to immediate mobilization or a short period of bed rest (up to 8 hours) and 1128 patients assigned to a longer period of bed rest (0.5 to 24 hours). Puncture was performed for anesthesia (5 trials), myelography (6 trials) and diagnostic reasons (5 trials). None of the trials showed that longer bed rest was superior to immediate mobilization or short bed rest for preventing headache after puncture. When pooling the results of the trials in the myelography group and the diagnostic group, the relative risks of headache after puncture were 0.93 (95% confidence interval [CI] 0.81-1.08) and 0.97 (95% CI 0.79-1.19) respectively. We did not pool the results from the trials in the anesthesia group because of clinical heterogeneity, but shorter bed rest appeared to be superior. INTERPRETATION: There was no evidence that longer bed rest after cervical or lumbar puncture was better than immediate mobilization or short bed rest in reducing the incidence of headache.

Bed Rest↗
PubMed2003

[Puncture aspiration using ultrasound guidance in the treatment of abscesses and other purulent foci in the liver, pancreas and kidneys].

The authors deal with the problem of application of a therapeutic fine needle aspiration puncture in abscesses and other purulent foci in organs of abdominal cavity and retroperitoneum. The treatment using this method under continuing antibiotic therapy has been used in 60 patients (40 men, 20 women), 25 of them suffering from liver abscesses, 28 other from purulent foci of pancreas and seven patients from purulent foci of the kidney. In most patients there were solitary foci (43 persons). The total volume of the evacuated pus was higher than 20 ml in most patients (52), being even more than 100 ml in 2 patients. No relation ship was found among the number of foci, their volume and efficiency of the treatment. The average number of punctures until the abscesses and other purulent foci were healed up was 2.76 in the liver, 2.5 in pancreas and 1.1 in the kidney. The efficiency of therapy was higher in liver abscesses (96%), in purulent foci of pancreas (82%) and lower in the kidney abscesses (57%). The higher efficiency in the purulent foci of pancreas was probably influenced by predominant representation by infected pseudocysts in this group. The lower average number of punctures until the abscesses were healed up and the lower success in the kidney were influenced by a more radical approach of urologists who, having made the first evacuation puncture, performed a radical operation intervention. The complications were encountered in 9.5% of all punctures, being always insignificant. The results obtained demonstrated the contribution of aimed therapeutic aspiration puncture in the therapy of purulent foci of parenchymal organs of abdominal cavity and retroperitoneum as compared with surgical treatment. The advantage of the applied method in the therapy of purulent foci of the liver and pancreas may be seen in the higher success rate, low invasiveness and a low risk of complications together with a low financial cost and wide availability.

Abscess↗
PubMedDate not supplied

Microbiology of sinus puncture versus middle meatal aspiration in acute bacterial maxillary sinusitis.

BACKGROUND: Maxillary sinus puncture is considered the gold standard for diagnosing acute bacterial maxillary sinusitis (ABMS) and for identifying bacterial pathogens in antimicrobial trials of ABMS. However, sinus puncture and aspiration is all invasive, time-consuming procedure that is limited by discomfort to the patient and possible complications. Therefore, the diagnostic usefulness in clinical practice and patient enrollment in studies of ABMS is hindered and alternatives for maxillary sinus puncture are being investigated. METHODS: We designed a prospective clinical and microbiological outpatient study. Cultures obtained by endoscopically guided middle meatal aspiration were compared with those from sinus puncture and aspiration in 24 patients with ABMS. RESULTS: Considering puncture and aspiration as the gold standard, endoscopy cultures provided a sensitivity of 80%, specificity of 100%, positive predictive value of 100%, negative predictive value of 78.6%, and correlation of 88.5%. CONCLUSION: In our study, endoscopic sampling compared favorably with sinus puncture and aspiration.

Adolescent↗
PubMed2006

[Development of incidence of post-dural puncture headache in patients undergoing caesarean section in spinal anaesthesia at the Department of Obstetrics and Gynecology in Olomouc during 2003-2004].

BACKGROUND: Paper gives the analyse of the incidence of post-dural puncture headache in patients undergoing caesarean section in spinal anaesthesia at the Department of Obstetrics and Gynecology in Olomouc in 2003-2004. METHODS AND RESULTS: Post-dural puncture headache following caesarean section in spinal anaesthesia in 2003 was retrospectively analysed. Subsequently, measures to reduce the incidence of this complication (use of Whitacre and Atra ucan needles) were implemented. 2004 patients were followed prospectively. 54 caesarean sections - 16.3% (54/331) were performed in spinal anaesthesia in 2003. Following needles were used to establish spinal blockade: Quincke 22G - 35.2% (19/54), Quincke 25G - 50% (27/54), Atraucan 26G - 14.8% (8/54). Post-dural puncture headache occurred in 9 cases - 16.6% (9/54) (22G - 7x, 25G - 2x), the onset of symptoms occurred after 24 to 65 hours after the spinal blockade (mean 41.7). It was necessary to perform epidural blood patch (EBP) in 7 cases - 77% (7/9) - 12.9% (7/54) (22G - 5x, 25G - 2x). Epidural blood patch (EBP) was performed after 7 to 45 hours after the onset of symptoms (median 28.4). The age of patients at the time of delivery ranged between 22 to 43 years (median 34.5). 36 caesarean sections - 8.4% (36/426) were performed in spinal anaesthesia in 2004. Following needles were used to establish spinal blockade: Whitacre 27G - 63,9% (23/36), Atraucan 26G - 13,9% (5/3), Quincke 25G - 11,1 (4/36), Quincke 22G - 11,1% (4/36). Post-dural puncture headache (PDPH) occurred in 3 cases - 8.3 (3/36) (25G - 1x, 22G - 2x), the onset of symptoms occurred after 24 to 54 hours after spinal blockade (median 36.0). It was not necessary to perform epidural blood patch. The age of patients at the time of delivery ranged between 22 to 39 years (median 28.5). CONCLUSIONS: Incidence of post-dural puncture headache (PDPH) is significantly higher in pregnant women and in puerperal period compared to general population. The use of appropriate needles for spinal blockade and adequate level of anaesthesiologist's skills lead to lower incidence of post-dural puncture headache (PDPH) after caesarean section performed in spinal anaesthesia.

Adult↗
PubMed1991

[Treatment of hepatic and juxta-hepatic abscesses by puncture-drainage].

The aim of this study was to show the result obtained by ultrasound-- or CT--guided puncture, possibly associated with transcutaneous drainage, for the treatment of hepatic and perihepatic abscesses. Preoperative imaging guides this treatment. It may reveal cavities as small as 1.5 cm in diameter. This nonsurgical treatment is based on single or multiple punctures, possibly followed by a long percutaneous drainage. The ideal indication is isolate liver abscesses located near the surface, as well as all juxtahepatic suppurative collections. Our experience is based on 73 patients, 32 of them presenting with an intrahepatic abscesses and 41 with a subphrenic or juxtahepatic abscess. For intrahepatic abscesses, healing was obtained with the surgical treatment in 75.3% of all cases: with a single puncture in 5 cases, two or more punctures in 4, and transcutaneous drainage in 11. Out of the 34 cases of perihepatic abscesses that underwent nonsurgical treatment, surgery was avoided in 25 cases, ie. 73.5% of all. Four of them were treated with a single puncture, 3 with repeated puncture, and 18 with transcutaneous drainage. The success of this procedure depends both on the indication and, most importantly, on the accurate application of the procedure.

Adult↗
PubMed1985

Serial lumbar punctures for at least temporary amelioration of neonatal posthemorrhagic hydrocephalus.

Serial lumbar punctures for the management of neonatal posthemorrhagic hydrocephalus without intracranial hypertension were evaluated in 16 infants. Cranial ultrasonography to evaluate ventricular size and the Ladd monitor at the anterior fontanel to measure intracranial pressure were utilized immediately before and after lumbar puncture. In 12 patients, a decrease in ventricular size and in anterior fontanel pressure could be effected with each lumbar puncture. In these infants, cessation of progression of the hydrocephalus and intermittent decreases in ventricular size were accomplished. In four patients, lumbar punctures were not successful in decreasing ventricular size or lowering intracranial pressure. Two criteria could be defined to determine whether lumbar puncture could provide at least temporary benefit for the treatment of posthemorrhagic hydrocephalus. The first of these is to establish the presence of communication between lateral ventricles and lumbar subarachnoid space by effecting a decrease in ventricular size and a decrease in intracranial pressure by removal of CSF. The second criterion is to ascertain a critical volume of CSF (usually relatively large) that must be removed in order to effect the above changes. Cranial ultrasonography and measurement of intracranial pressure by application of the Ladd monitor to the anterior fontanel are extremely valuable in the evaluation of lumbar punctures in the management of posthemorrhagic hydrocephalus.

Cerebral Hemorrhage↗
PubMed1973

Cisternal puncture complications. Treatment of coccidioidal meningitis with amphotericin B.

Of two patients who had acute neurologic damage from cisternal punctures, one died 17 hours following a tap which produced major subarachnoid hemorrhage, the other patient recovered from probable brain stem infarction associated with cisterna magna amphotericin injection. Subarachnoid hemorrhage is the commonest major complication of cisternal puncture, with at least 30 reported fatalities. Other serious complications result from direct puncture of brain substance.Cisternal puncture is not an appropriate alternative to a difficult lumbar puncture, and indications for its use are limited. The occasional required cisternal tap should be performed only by persons carefully trained in the technique, preferably utilizing fluoroscopic guidance, and only where neurosurgical assistance is readily available.Post-puncture subarachnoid hemorrhage accompanied by progressive obtundation requires emergency evaluation and consideration of posterior fossa decompression.

Adult↗
PubMed1983

Methods in laboratory investigation. Identification and evaluation of histopathology at microelectrode puncture sites.

Tissue puncture techniques using microelectrodes for various measurements have been criticized for producing undetermined degrees of tissue damage. Therefore, a method permitting routine identification of puncture tracks was developed to determine local microelectrode-induced injury. Rabbits were anesthetized and the femoral arteries surgically exposed. A 3-ml mixture of saline-India ink suspension was introduced through an ear vein. Oxygen-sensitive (pO2) microcathodes were advanced into and through the arterial wall at 10- or 20-micron intervals using a stepping microdrive to 150 to 450 micron and then withdrawn. The arteries were fixed in 10% formalin and gelatin embedded, and serial frozen sections (less than or equal to 15 micron) of the microelectrode puncture area were made. We observed within 5 minutes of microcathode withdrawal a dark, punctate, microscopic discoloration within the arterial wall. Histologically, ink distribution within the arterial wall demonstrated an acute permeability change: puncture depths generally less than 300 micron showed ink-lined microelectrode tracks (generally less than 2 micron wide) in the media, and greater puncture depths showed local hemorrhage and focal laminar accumulation of ink which extended from the track. The immediate adjacent area to microelectrode puncture depths less than 300 micron showed an apparent intact internal elastic lamina and media. Therefore, microelectrode damage has been shown to be primarily limited to microelectrode tissue tracks.

Animals↗