Chiari malformation: CSF flow dynamics in the craniocervical junction and syrinx.

BACKGROUND: A CSF flow study in patients with Chiari malformation (ChM) who undergo craniocervical junction decompression (CCJD). METHODS: Using spatial modulation of magnetization (SPAMM), cerebrospinal fluid (CSF) flow velocities were measured at the prepontine (PP), anterior cervical (AC), and posterior cervical (PC) subarachnoid spaces (SAS) in healthy subjects (n = 11) and patients with Chiari malformation (ChM) before and/or after CCJD (n = 15). In the syringes, the intrasyrigeal pulsatile CSF motion was estimated qualitatively as present or absent. FINDINGS: In normal subjects, the mean CSF velocities were 2.4 +/- 0.2 cm/s (PP), 2.8 +/- 0.3 cm/s (AC), and 2.4 +/- 0.2 cm/s (PC). Velocities were significantly lower than normal in patients with ChM prior to CCJD, reduced by 38%, 25%, and 79% in the 3 regions, respectively (P<0.001). Post-CCJD, velocities were 20% (PP), 100% (AC), and 40% (PC) greater than preoperatively (P<0.001). CONCLUSIONS: In ChM, the posterior cervical CSF flow velocity was low, increased minimally after CCJD and, by itself, had limited predictive value. Post-CCJD, an increase of the sum of anterior and posterior cervical CSF flow velocities by more than 20% consistently preceded or coincided with marked headache improvement. After CCJD, the finding that the intrasyringeal CSF pulsatile motion had become absent was an earlier and more sensitive predictor of motor or sensory improvement than a reduction in syrinx's size. SPAMM can be used to assess whether CCJD has restored CSF flow, predict outcome and provide pathophysiological insights in ChM and syringomyelia.

Treatment of overactive bladder (OBA) with anti-cholinergic drugs and the risk of glaucoma.

Overactive bladder (OAB) and glaucoma are prevalent and frequently co-exist, particularly in the elderly. Anti-cholinergic drugs are the cornerstone of medical management of OAB. There is a great deal of confusion about the safety of use of the anti-cholinergic medication regarding the risk of glaucoma. This review examines the pharmacological relationship of anti-cholinergic medications used to treat OAB and the various types of glaucoma.

Prospective survey of adverse reactions to topical antiglaucoma medications in a hospital population.

AIM: To identify the relative incidence and profile of adverse drug reaction (ADR) to various topical ocular hypotensives in a hospital setting. METHODS: All the patients presenting in outpatients clinic and accident and emergency with an ADR to topical hypotensive agent from August 2000 to January 2001 were included in the study. Details regarding the type date of commencing the treatment, the date of developing ADR, time to resolution of the ADR were noted. RESULTS: Over the period of 6 months, 66 patients presented with 73 ADRs. Brimonidine was the most frequent offending agent. In total, 23 (34.8%) presented with ADR after being commenced on treatment for more than 12 months. In all, 16 (24%) patients had IOP > 21 on presentation, eight (12%) patients underwent filtration surgery following the development of ADR. CONCLUSION: Adverse drug reaction to ocular hypotensive agents is not uncommon and can have a major impact on glaucoma management. Delayed presentation and association with raised intraocular pressure presentation emphasise the need for effective patient education to encourage prompt reporting of ADR.

Otago Glaucoma Surgery Outcome Study: long term results of cataract extraction combined with Molteno implant insertion or trabeculectomy in primary glaucoma.

BACKGROUND/AIMS: To describe the long term results of cases of cataract extraction combined with either Molteno implant insertion or trabeculectomy for primary open angle glaucoma. METHODS: This prospective case series followed cases which had cataract extraction and Molteno implant insertion (45 eyes) or trabeculectomy (94 eyes) followed up for a mean of 5.3 years and 3.9 years respectively. RESULTS: Cataract extraction and Molteno implant insertion or trabeculectomy controlled the intraocular pressure at 21 mmHg or less with a probability of 1.00 (95% CI 0.93 to 1.00) at 10 years or more after operation and 0.94 (95% CI 0.89 to 0.99) and 0.73 (95% CI 0.46 to 0.99) at five and 10 years after operation respectively. CONCLUSIONS: Cataract extraction combined with insertion of Molteno implants or trabeculectomy controlled the intraocular pressure in 100% (45/45) and 94% (88/94) of cases respectively.

Exercise-induced visual loss associated with advanced glaucoma in young adults.

PURPOSE: To highlight the phenomenon of exercise-induced visual loss associated with advanced glaucoma and to discuss the possible underlying mechanisms. METHODS: Three young adult patients with congenital or juvenile-onset glaucoma presenting with visual loss which occurred during exercise underwent ophthalmic examination. In 2 cases, visual function parameters, including visual fields (Humphrey full threshold perimetry) were measured before and after exercise. RESULTS: All patients clearly described visual loss during exercise. In the 2 cases in which data were available, significant impairment in central visual acuity and reduced foveal sensitivity and mean deviation on visual field analysis occurred during exercise of mild to moderate intensity with complete or near complete recovery of visual function upon cessation of exercise. CONCLUSION: Young patients with advanced glaucomatous optic neuropathy should be questioned regarding exercise-induced visual disturbance. We hypothesise that a 'vascular steal' is the likely mechanism underlying this phenomenon. Patients should be advised to limit activities which induce their symptoms, and therapeutic measures to promote ocular blood flow should be considered.

Latent proliferative sickle cell retinopathy in sickle cell trait.

PURPOSE: To describe a patient with sickle cell trait who developed latent proliferative sickle cell retinopathy after mild blunt trauma. METHOD: Case Report. A 20-year-old man with unilateral Stage 3 sickle retinopathy associated with an ischaemic ridge presenting three years after the initial mild blunt ocular trauma. RESULTS: Fundus examination of the left eye showed an ischaemic ridge delineating avascular from vascular retina. Fluorescein angiography of the left eye showed an avascular peripheral retina and multiple sea fan neovascularization. Blood studies showed him to be Hb AS. CONCLUSIONS: In our patient the proliferative changes were the result of his initial mild trauma associated with an increase in the intraocular pressure. The latent development of the sea-fan neovascularization associated with an ischaemic ridge is unusual. Advice about potential complications to patients with Hb AS after ocular trauma is advocated.

Is the role of trabeculectomy in glaucoma management changing?

BACKGROUND: In recent years there have been significant developments in the diagnosis and treatment of glaucoma. We conducted a study to determine whether there has been an associated change in trabeculectomy rates in England over this period. METHODS: Figures for the total number of trabeculectomies and cataract operations performed in England for each year from 1989/90 to 1999/2000 were obtained from the Department of Health, Hospital Episode Statistics Division. RESULTS: The available data show that the number of trabeculectomies and cataract operations increased year on year from 1990/91 until 1995/96. Since then, the number of cataract procedures has continued to rise dramatically, whereas the number of trabeculectomies has fallen progressively by 7%, 23%, 37% and 53% in the last 4 years. CONCLUSION: The perceived need for surgical intervention would appear to have been delayed or prevented. We postulate that several factors underlie this trend and that there are a number of implications regarding the future management of glaucoma patients.

Diagnosis of amblyopia using the 10-diopter fixation test: a proposed modification for patients with unilateral ptosis.

PURPOSE: The 10-diopter (D) fixation test is a useful test for detecting amblyopia in children without a manifest deviation and in whom a reliable visual acuity assessment is difficult. The 10 prism diopter is conventionally placed base down. METHODS: Seventeen children were studied over a 12-month period to determine the effect of prism orientation on the accuracy of the 10-D fixation test in children with unilateral ptosis. RESULTS: Anomalous results were obtained in 4 of 17 patients with the prism held base up and base down. CONCLUSIONS: To prevent an erroneous diagnosis of amblyopia in children with unilateral ptosis, the prism should be held base up when performing the 10-D fixation test.

Non-communication between ophthalmologists and optometrists.

Many patients seen in the British hospital eye service are referred by high-street optometrists; and, if the optometrist is to receive feedback from the ophthalmologist, the patient should consent to disclosure of medical information. On the referral form (revised GOS 18) there is a space for this purpose. We investigated the level of communication by asking optometrists in our hospital catchment area about their use of the GOS 18 form and by examining the medical records of all new patients seen in the eye outpatient department in one month. 79 optometrists (55%) returned the questionnaire. 54 routinely used the GOS 18; and, of these, 10 said they obtained patient consent always, 23 sometimes and 21 never. 158 of 555 sets of medical notes contained an optometrist's referral, 107 of them on the revised GOS 18; and patient consent had been recorded on 17 of these forms. Ophthalmologists responded to the optometrist in 2/17 (12%) cases where consent had been obtained and 15/90 (17%) where it had not. Ophthalmologists could provide much better feedback to optometrists. The GOS 18 form could be used more effectively; and there is no reason why patient consent to disclosure of medical information should not be obtained by ophthalmologists as well as by optometrists.

Compound anterior cranial base fractures: classification using computerized tomography scanning as a basis for selection of patients for dural repair.

OBJECT: A classification is proposed to organize anterior cranial base fractures systematically according to their location and size. The goal of this study was to determine whether these two variables, irrespective of cerebrospinal fluid (CSF) rhinorrhea, are related to the long-term risk of posttraumatic meningitis and, hence, to standardize decision making concerning surgical repair of associated CSF fistulas. METHODS: With the aid of high-resolution thin-section coronal computerized tomography (CT) scanning, anterior cranial base fractures were classified into the following four major types: I, cribriform; II, frontoethmoidal; III, lateral frontal; and IV, complex (any combination of the other three types). Fractures with a maximum bone displacement that extended farther than 1 cm in any plane were classified as "large" and those less than 1 cm as "small." The authors used this classification in a study of 48 patients who were treated by conservative (20 patients) or surgical (28 patients) means. The results showed a gradation of risk: the fracture most likely to develop infection was a large cribriform (Type I) and the least likely was a small lateral frontal (Type II). Statistical analysis showed that the trend for an increased infection rate was related to the cumulative effect of three variables in the following order: 1) prolonged duration of rhinorrhea (analysis of variance [ANOVA], p = 0.017); 2) large size of fracture displacement (ANOVA, p = 0.079); and 3) fracture's proximity to the midline (ANOVA, p = 0.015). CONCLUSIONS: In this series, microsurgical repair was accompanied by a minimum complication rate. Hence, the authors recommend that patients with fractures that combine the aforementioned variables should be considered to have a high long-term risk of infection and their injury should be surgically repaired as soon as the posttraumatic edema has subsided. This applies to the following fractures: large cribriform (Type I) with transient rhinorrhea lasting 5 to 8 days and large frontoethmoidal (Type II) with prolonged rhinorrhea lasting longer than 8 days. Furthermore, the authors conclude that this classification can improve the management of posttraumatic CSF fistulas of the anterior cranial base and may provide insights into the mechanisms underlying their spontaneous repair and susceptibility to meningitis.

Syndromes of posttraumatic neurological deterioration in children with no focal lesions revealed by cerebral imaging: evidence for a trigeminovascular pathophysiology.

PURPOSE: To explain the pathophysiology of the neurological deterioration that occurs after trivial head injuries in children and that is not caused by focal structural brain damage. Symptoms and/or signs include headache, confusion, drowsiness, vomiting, hemiparesis, cortical blindness, and seizures. CONCEPT: We propose that children who are susceptible to such neurological attacks have an unstable "trigeminovascular reflex," which is activated by craniofacial trauma. RATIONALE: After posttraumatic mechanical stimulation and activation of a defective or immature "excitable" trigeminovascular system, release of perivascular vasodilatory peptides causes cerebral hyperemia, which underlies the neurological deterioration. DISCUSSION: The original assumption that underlying cerebral edema was responsible for these phenomena has been proven incorrect by computed tomography. Subsequent proposed pathophysiological mechanisms include cortical spreading depression and trauma-triggered migraine. Recent research has implicated the trigeminovascular pathways in both these conditions and documented that head trauma can be associated with noncongestive cerebral hyperemia (i.e., not causing swelling). Thus, we propose that head trauma activates trigeminal nerve endings in face, scalp, dura, or cortex and, via a reflex, causes intracranial vasodilation and cerebral hyperemia. Drugs that block trigeminovascular activation might offer a benefit.

Logistics of performing an ophthalmic assessment in elderly inpatients.

To assess the feasibility of performing an ophthalmic assessment on elderly inpatients, we examined 48 patients over 75 years of age who were consecutively admitted to an acute elderly-care ward. Difficulties were encountered in 35 patients (73%). By employing simple methods to overcome these problems, useful information was obtained in all cases and the time taken to complete the examination ranged from six to 20 minutes (mean 7.5 minutes). Doctors looking after elderly patients should be encouraged to assess visual function and must not be deterred by anticipated logistical difficulties.

Perfluorocarbons: recent developments and implications for neurosurgery.

Over the last 30 years, perfluorocarbons (PFCs) have been extensively investigated as oxygen carriers. Early studies indicated that these compounds could be used as blood substitutes or protective agents against ischemia. Adverse characteristics such as instability, short intravascular half-life, and uncertainties concerning possible toxicity precluded wide clinical application. However, advances in PFC technology have led to the development of improved second-generation oxygen carriers that incorporate well-tolerated emulsifiers (egg-yolk phospholipids). The authors review recent developments in this field and consider the potential role of PFCs in future neurosurgical practice. Diagnostic applications could include their use to assess cerebral blood flow, local oxygen tension, and brain metabolism or to achieve enhanced imaging and precise staging of inflammatory, neoplastic, or vascular disease processes by means of computerized tomography, ultrasonography, and magnetic resonance studies. Therapeutic applications could include cerebral protection, an adjunctive role in radiotherapy of malignant brain tumors, protection against air embolism, the preservation of organs for transplantation, and ventilatory support in head-injured patients with compromised lung function. In addition, PFCs have been used successfully as a tool in ophthalmic microsurgery and potentially they could fulfill a similar role in microneurosurgery.