Tuberous sclerosis is one of the few established medical causes of autism spectrum disorder and is a unique neurogenetic model for testing theories about the brain basis of the syndrome. We conducted a retrospective case study of the neuro-epileptic risk factors predisposing to autism spectrum disorder in individuals with tuberous sclerosis to test current neurobiological theories of autism spectrum disorder. We found that an autism spectrum disorder diagnosis was associated with the presence of cortical tubers in the temporal but not other lobes of the brain. Indeed, the presence of tubers in the temporal lobes appeared to be a necessary but not sufficient risk factor for the development of an autism spectrum disorder. However, contrary to the predictions of some theories, the location of tubers in specific regions of the temporal lobe, such as the superior temporal gyrus or the right temporal lobe, did not determine which individuals with temporal lobe tubers developed an autism spectrum disorder. Instead, outcome was associated with various indices of epileptic activity including evidence of temporal lobe epileptiform discharges on EEG, the age to onset of seizures in the first 3 years of life and a history of infantile spasms. The results indicated that individuals with tuberous sclerosis are at very high risk of developing an autism spectrum disorder when temporal lobe tubers are present and associated with temporal lobe epileptiform discharges and early-onset, persistent spasm-like seizures. These risk markers constitute useful clinical indicators of prognosis, but further research is required to identify the neurobiological mechanisms responsible for their association with outcome. Most especially, it will be important to test whether, as the findings suggest, there is a critical early stage of brain maturation during which temporal lobe epilepsy perturbs the development of brain systems that underpin 'social intelligence' and possibly other cognitive skills, thereby inducing an autism spectrum disorder.

Background: The high pressures documented in the intracranial venous sinuses in idiopathic intracranial hypertension (IIH) could be the result of focal stenotic lesions in the lateral sinuses obstructing cranial venous outflow. Objective: To explore the relation between venous sinus disease and IIH. Methods: 12 patients with refractory IIH had dilatation and stenting of the venous sinuses after venography and manometry had shown intracranial venous hypertension proximal to stenoses in the lateral sinuses. Intrasinus pressures were recorded before and after the procedure and correlated with clinical outcome. Results: Intrasinus pressures were variably reduced by stenting. Five patients were rendered asymptomatic, two were improved, and five were unchanged. Conclusions: The importance of venous sinus disease in the aetiology of IIH is probably underestimated. Lateral sinus stenting shows promise as an alternative treatment to neurosurgical intervention in intractable cases.

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Background: Venous sinus disease must be excluded before diagnosing idiopathic intracranial hypertension but is found only rarely in typical cases. Magnetic resonance venography (MRV) is the technique of choice for investigating this, and provides images that are diagnostic and easy to interpret. However, recent work using more invasive techniques has documented pressure gradients and stenoses in the lateral venous sinuses in many cases of idiopathic intracranial hypertension. Objective: To examine the reason for this discrepancy and to establish whether there are characteristic appearances on MRV in idiopathic intracranial hypertension that are routinely overlooked in clinical practice. Methods: MRVs from 20 patients with idiopathic intracranial hypertension were reviewed, unblinded, by two neuroradiologists, and their appearances rated for focal narrowings and signal gaps. A control group of 40 asymptomatic volunteers, matched for age and sex with the patient group, was recruited prospectively for MRV, and their scans rated in the same way. Results: The lateral sinuses presented a range of appearances with quite different distributions in the two groups (p,0.001). Bilateral lateral sinus flow gaps were seen in 13 of 20 patients with idiopathic intracranial hypertension and in none of 40 controls. Conclusions: A historical failure to use normal healthy controls to establish the boundaries between imaging artefact, normal anatomical variant, and disease means that the pathological significance of the different appearances of the lateral sinuses on MRV has not so far been appreciated.

Genetic testing can be valuable in confirming the diagnosis. Increasing numbers of cases present prenatally or in early infancy, before onset of seizures, raising important questions about whether these children should have EEG monitoring and concerning the criteria for starting anticonvulsant therapy.