Wayne T. Cornblath, MD, discusses advances in diagnostic criteria, monitoring ability and disease etiology that have occurred in the last year that he says will improve the ability to care for patients. They span the areas of idiopathic intracranial hypertension (IIH), giant cell arteritis (GCA), third nerve palsy from posterior communicating artery aneurysm, OCT and congenital cranial dysinnervation disorders (CCCDs).
1. If left untreated, IIH can produce severe visual loss. A series of studies in normal pediatric patients measured CSF opening pressure. A normal range of 11 to 32 cm of water was established. Moderate to deep sedation produced a slightly higher opening pressure. In patients with an opening pressure below 20 cm, extending the legs will change the pressure a small amount.
Occasionally, in a patient with an opening pressure greater than 20 cm, a more significant pressure drop will occur with extending the legs and this should be done to arrive at the correct diagnosis. Prior to these articles, pressures greater than 18 cm of water were thought to be abnormal in children, and the effect of leg flexion vs. leg extension was not known.
2. Work in progress has shown that infection with Burkholderia pseudomallei may be the inciting agent in GCA. While patients with GCA do well with prednisone only, there is significant morbidity with long-term prednisone use. In very preliminary work, the level of lipopolysaccharide from Burkholderia has been shown to drop with antibiotic treatment plus prednisone but not with prednisone treatment only. Hence doxycycline 100 mg twice daily, along with prednisone 60 mg daily, may be a reasonable starting treatment plan in GCA patients.
3. Detection of third-nerve palsy from posterior communicating artery aneurysm before the aneurysm ruptures dramatically reduces morbidity and mortality. Computed tomography, angiogram and magnetic resonance angiogram are often used to detect aneurysm, and their rate of detection is very similar. However, radiologist accuracy in diagnosing aneurysmal third nerve palsy varies widely among institutions.
While the technology exists for early diagnosis of aneurysmal third nerve palsy, it must be implemented correctly. Ordering physicians have an obligation to provide the correct clinical history to the radiologist interpreting a test and to make sure that a qualified radiologist has reviewed the films.
4. OCT can now provide very accurate measurements of either the macula or the retinal nerve fiber layer (RNFL) that can be repeated over time. Given that up to 20 percent of adult patients and children under the age of 10 years cannot accurately perform visual field testing, OCT can be used to follow changes in RNFL thickness as a surrogate for changes in visual field testing. The role of OCT in multiple sclerosis, vigabatrin toxicity and optic nerve glioma also is discussed.
5. Recent work with families with multiple affected members has led to the discovery of genetic mutations responsible for CCCDs. These include Duane type I and III; Mobius syndrome; congenital fibrosis of extraocular muscles types 1, 2 and 3; and horizontal gaze palsy with progressive scoliosis. Hereditary congenital ptosis and hereditary congenital facial palsy are CCCD syndromes with normal ocular motility.
A variety of other symptoms, limb abnormalities and cognitive disorders can be seen with some of these syndromes. When seeing patients with these findings, there is now a framework to better classify and genetically diagnose these conditions. As genetic testing advances, the ability to accurately diagnose and provide prognostic information for patients and potential offspring will continue to improve.