Wolf Lüdemann

Dynamic properties of lymphatic pathways for the absorption of cerebrospinal fluid

Abstract To study the dynamics of the outflow of cerebrospinal fluid (CSF) into the cervical lymphatic system, X-ray contrast medium or Indian ink was infused into the cisterna magna of rats at moderately increased intracranial pressure (40–50 mm Hg). In the first series of experiments, while the contrast medium was being infused, the animal’s head was examined using X-ray-microscopy (× 4–20 direct magnification radiography) and conventional radiography. Within the first minutes of infusion, the flow of CSF was directed from the posterior fossa to the olfactory bulb. Reaching the cribriform plate approximately 7 min after starting the infusion, the contrast medium leaked into the nasal cavities. Some minutes later, it opacified the subarachnoid space (SAS) of the optic nerve, the perilymphatic space of the inner ear, the cortical SAS, and the transverse sinuses. Leakage from the optic nerve SAS into the orbit was seen after 30 min infusion. In the second series of experiments, the Indian ink was infused after microsurgical exposure of the cervical lymph vessels. During the infusion the cervical lymph ducts were observed microscopically (× 40 magnification). Single dye particles draining through the cervical lymph ducts appeared 20 min after the start of cisternal infusion. Their transport was rapid, and dependent on the respiratory cycle: during inspiration the particles moved at a speed of 10–20 mm/s, during expiration the movement stopped. Thus, rapid kinetics are demonstrated for the outflow of CSF and particles from the SAS into the cervical lymphatics.

Effect of Celecoxib and Dexamethasone on Postoperative Pain after Lumbar Disc Surgery

OBJECTIVEThis study was designed to assess the efficacy of perioperative administration of celecoxib (Celebrex; Pharmacia GmbH, Erlangen, Germany) in reducing pain and opioid requirements after single-level lumbar microdiscectomy. METHODSWe studied 34 patients (mean age, 44.26 yr; standard deviation [SD], 13.09 yr) allocated randomly to receive celecoxib 200 mg twice a day for 72 hours starting on the evening before surgery or placebo capsules in a double-blind study. Fourteen patients received 20 to 80 mg dexamethasone intravenously during surgery (mean, 40 mg; SD, 19.22 mg) because of visible signs of compression of the affected nerve root. After lumbar disc surgery, patients were monitored for visual analog scores for pain at rest and on movement, patient-controlled analgesia (PCA) piritramide requirements, and von Frey thresholds in the wound area. RESULTSPain scores decreased and wound von Frey thresholds increased continuously until discharge, with no intergroup differences. Mean 24-hour PCA piritramide requirements were 22.63 mg (SD, 23.72 mg) and 26.14 mg (SD, 22.57 mg) in the celecoxib and placebo groups, respectively (P = not significant). However, patients with intraoperative dexamethasone (n = 14) required only 10.29 mg (SD, 8.55 mg) 24-hour PCA piritramide, in contrast to the 34.25 mg (SD, 24.69 mg) needed in those who did not receive intraoperative dexamethasone (P = 0.001). In addition, 24 hours after the operation, pain scores on movement were significantly lower in the dexamethasone subgroup (P = 0.003). CONCLUSIONCelecoxib has no effect on postoperative pain scores and PCA piritramide requirements. The intraoperative use of 20 to 80 mg dexamethasone is able to significantly decrease postoperative piritramide consumption and pain scores on the first day after surgery.

Treatment of Refractory Pain after Brachial Plexus Avulsion with Dorsal Root Entry Zone Lesions

OBJECTIVE: Significant numbers of patients experience intractable pain after brachial plexus root avulsions. Medications and surgical procedures such as amputation of the limb are often not successful in pain treatment. METHODS: Forty-seven patients with intractable pain after traumatic cervical root avulsions were treated with dorsal root entry zone coagulation between 1980 and 1998. The dorsal root entry zone coagulation procedure was performed 4 months to 12 years after the trauma, and patients were monitored for up to 18 years (average follow-up period, 14 yr). RESULTS: Immediately after surgery, 75% of patients experienced significant pain reduction; this value was reduced to 63% during long-term follow-up monitoring. Nine patients experienced major complications, including subdural hematomas (n = 2) and motor weakness of the lower limb (n = 7). Improved coagulation electrodes with thermistors that could produce smaller and more-accurate lesion sizes, which were introduced in 1989, significantly reduced the number of complications. CONCLUSION: Central deafferentation pain that persists and becomes intractable among patients with traumatic cervical root avulsions has been difficult to treat in the past. Long-term follow-up monitoring of patients who underwent the dorsal root entry zone coagulation procedure in the cervical cord indicated that long-lasting satisfactory relief is possible for the majority of individuals, with acceptable morbidity rates.

Microvascular decompression for trigeminal neuralgia in the elderly: long-term treatment outcome and comparison with younger patients.

OBJECTIVEMultiple studies have proved that microvascular decompression (MVD) is the treatment of choice in cases of medically refractory trigeminal neuralgia (TN). In the elderly, however, the surgical risks related to MVD are assumed to be unacceptably high and various alternative therapies have been proposed. We evaluated the outcomes of MVD in patients aged older than 65 years of age and compared them with the outcomes in a matched group of younger patients. The focus was on procedure-related morbidity rate and long-term outcome. METHODSThis was a retrospective study of 112 patients with TN operated on consecutively over 22 years. The main outcome measures were immediate and long-term postoperative pain relief and neurological status, especially function of trigeminal, facial, and cochlear nerves, as well as surgical complications. A questionnaire was used to assess long-term outcome: pain relief, duration of a pain-free period, need for pain medications, time to recurrence, pain severity, and need for additional treatment. RESULTSThe mean age was 70.35 years. The second and third branches of the trigeminal nerve were most frequently affected (37.3%). The mean follow-up period was 90 months (range, 48–295 months). Seventy-five percent of the patients were completely pain free, 11% were never pain free, and 14% experienced recurrences. No statistically significant differences existed in the outcome between the younger and older patient groups. Postoperative morbidity included trigeminal hypesthesia in 6.25%, hypacusis in 5.4%, and complete hearing loss, vertigo, and partial facial nerve palsy in 0.89% each. Cerebrospinal fluid leak and meningitis occurred in 1 patient each. There were no mortalities in both groups. CONCLUSIONMVD for TN is a safe procedure even in the elderly. The risk of serious morbidity or mortality is similar to that in younger patients. Furthermore, no significant differences in short- and long-term outcome were found. Thus, MVD is the treatment of choice in patients with medically refractory TN, unless their general condition prohibits it.

Ultrastructure of the cerebrospinal fluid outflow along the optic nerve into the lymphatic system

ObjectTo explain the spontaneous CSF outflow into the orbit, the ultrastructure of the perineural meningeal layers at the distal and the proximal portions of the optic nerve were compared.MethodsTen cats were perfusion fixated and the orbital content removed for transmission and scanning electron microscopy. In five animals a 60-min cisternal infusion of contrast medium at low intracranial pressure was performed before perfusion fixation.ResultsIn the contrast-infused animals it was possible to demonstrate the leakage of contrast medium in the distal portion of the optic nerve sheath (ONS) from the subarachnoid space (SAS) into the orbit and find it in the conjunctival lymphatics. Electron microscopy revealed that in the distal portion of the ONS the neurothelial layers are significantly thinner, some consisting of only one layer. Pore-like openings in the neurothelial covering are seen in the distal portion. Excavations of the SAS are far more numerous in the distal portion of the ONS. The excavations reach the neurothelial layer. Intracellular and extracellular filaments are more numerous in the distal portion of the ONS. There is no significant difference in the dura mater between the distal and proximal ONS. The results show the existence of an arachnoid window area in the distal portion of the ONS. It is characterised by a continuous, but thinned neurothelial barrier layer, with few pore-like openings.ConclusionsThe main differences between distal and proximal ONS are a thinned neurothelial barrier layer and an increased number of intercellular filaments and pore-like openings. The findings explain the lymphatic CSF outflow pathway along the optic nerve.

Recent findings on the angioarchitecture of the lymph vessel system of human skin

Summary The regional distribution of initial (i.e. most peripheral) lymph vessels of the human skin is unknown. New methods permit a precise systematic determination of the density of initial lymph vessels in every region of the dermis.

Alterations in brain metabolism, CNS morphology and CSF dynamics in adult rats with kaolin-induced hydrocephalus

The present study describes the biochemical changes, morphological development and the cerebrospinal fluid dynamics of the kaolin-induced hydrocephalus in the adult rat. Two, 4 and 6 weeks after microsurgical kaolin instillation into the rat cisterna magna the basal intracranial pressure and the cerebrospinal fluid outflow resistance were measured. To determine possible biochemical changes in the rat cerebrum, brain stem and cerebellum the concentrations of glutamine, glutamate, glutathione, aspartate, GABA, alanine and taurine were measured by high pressure liquid chromatography. In addition, ventriculomegaly and syringomyelia were assessed, measuring the lateral ventricles and central canals by means of an image-processing computer program. It could be shown that the acute phase of kaolin-induced hydrocephalus in the first 4 weeks is characterised by a high basal intracranial pressure, a considerably increased CSF outflow resistance and a rise in brain water content in the fourth week. The changes in the concentrations of amino acids were moderate. Glutamine was increased and taurine was decreased in the cerebrum and alanine was increased in the brain stem. The chronic phase, however, is defined by normal basal pressure, declining outflow resistance, progression of ventriculomegaly and distinct changes in the biochemical parameters such as a remarkable decrease of glutamate, glutamine and taurine in the cerebellum, a decrease of taurine and alanine plus an increase in glutamine in the cerebrum and an increase of alanine in the brain stem. Moreover, cerebral metabolism in the adult rat seems to be more resistant to the effects of hydrocephalus than metabolism in neonatal and infantile rats.

Fat implant is superior to muscle implant in vestibular schwannoma surgery for the prevention of cerebrospinal fluid fistulae.

OBJECTIVE Meticulous sealing of opened air cells in the petrous bone is necessary for the prevention of cerebrospinal fluid (CSF) fistulae after vestibular schwannoma surgery. We performed a retrospective analysis to determine whether muscle or fat tissue is superior for this purpose. METHODS Between January 2001 and December 2006, 420 patients underwent retrosigmoidal microsurgical removal by a standardized procedure. The opened air cells at the inner auditory canal and the mastoid bone were sealed with muscle in 283 patients and with fat tissue in 137 patients. Analysis was performed regarding the incidence of postoperative CSF fistulae and correlation with the patients sex and tumor grade. RESULTS The rate of postoperative CSF leak after application of fat tissue was lower (2.2%) than after use of muscle (5.7%). Women had less postoperative CSF leakage (3.4%) than men (5.6%). There was an inverse correlation with tumor grade. Patients with smaller tumors seemed to have a higher rate of CSF leakage than those with large tumors without hydrocephalus. Only large tumors with severe dislocation of the brainstem causing hydrocephalus showed a higher incidence of CSF leaks. CONCLUSION Fat implantation is superior to muscle implantation for the prevention of CSF leakage after vestibular schwannoma surgery and should, therefore, be used for the sealing of opened air cells in cranial base surgery.

Astrocyte metabolism is disturbed in the early development of experimental hydrocephalus

The proper diagnosis of the arrested or the progressive form of hydrocephalus has a critical impact on treatment, but remains difficult. The assessment of early changes in cerebral metabolism might help in the development of adequate non‐invasive diagnostic tools. This study examined the alterations in label incorporation in neurotransmitter amino acids and other compounds in kaolin‐induced progressive hydrocephalus in rats by means of magnetic resonance spectroscopy (MRS) combined with the administration of [1‐13C]glucose and [1,2‐13C]acetate. Some 2, 4 and 6 weeks after kaolin injection into the cisterna magna, cerebrum, brainstem and cerebellum were dissected. Interestingly, labelling of most amino acids derived from [1‐13C]glucose showed no alterations, whereas labelling from [1,2‐13C]acetate was affected. Two weeks after induction of hydrocephalus the taurine concentration was decreased, whereas the concentration of [1,2‐13C]lactate was increased in the cerebrum and that of [1,2‐13C]GABA in the brainstem. Furthermore, labelling from [1,2‐13C]acetate was significantly decreased in [4,5‐13C]glutamate, [1,2‐13C]glutamate and [1,2‐13C]GABA in cerebrum from 4 weeks after hydrocephalus induction. The concentration of N‐acetylaspartate, a neuronal marker, was unchanged. However, labelling of the acetyl group from [1‐13C]glucose was decreased in cerebellum and brainstem at 6 weeks after the induction of hydrocephalus. As glucose is metabolized predominately by neurones, whereas acetate is exclusively taken up by astrocytes, these results indicate that mostly astrocytic, and only later neuronal, metabolism is disturbed in the kaolin model of hydrocephalus. If verified in patients using in vivo MRS, impaired astrocyte metabolism might serve as an early indication for operative treatment.

Sporadic unilateral vestibular schwannoma with islets of meningioma: case report.

OBJECTIVE AND IMPORTANCE Vestibular schwannomas with meningioma islets have been rarely reported in the literature; they have been observed only among patients with neurofibromatosis Type II. We present a case of a sporadic mixed tumor in a patient without neurofibromatosis Type II that was not suspected before surgery. CLINICAL PRESENTATION A 59-year-old female patient presented with clinical signs of progressive loss of hearing. Her family history did not include evidence of neurological diseases. Magnetic resonance imaging scans revealed a typical unilateral vestibular schwannoma. INTERVENTION The tumor presented with invasion of the surrounding arachnoid membrane, as well as Cranial Nerves VII and VIII. Preservation of the facial nerve with complete removal of the tumor was not possible. Therefore, Cranial Nerve VII reconstruction was performed. CONCLUSION The concomitant occurrence of schwannomas and meningiomas infiltrating the arachnoid membrane might be related to poor clinical outcomes for patients with neurofibromatosis Type II, with respect to preservation of facial and acoustic nerves. Among sporadic schwannomas, this phenomenon is extremely rare.