Manuel R. Gomez

Tuberous Sclerosis Complex Consensus Conference: Revised Clinical Diagnostic Criteria

At the recent tuberous sclerosis complex consensus conference, the clinical diagnostic criteria for tuberous sclerosis complex were simplified and revised to reflect both new clinical information about tuberous sclerosis complex and an improved understanding of the disorder derived from molecular genetic studies. Based on this new information, some clinical signs once regarded as pathognomonic for tuberous sclerosis complex are now known to be less specific. No single sign is present in all affected patients, and there is no proof that any single clinical or radiographic sign is absolutely specific for tuberous sclerosis complex. Accordingly, the clinical and radiographic features of tuberous sclerosis complex have now been divided into major and minor categories based on the apparent degree of specificity for tuberous sclerosis complex of each feature. A definitive diagnosis of tuberous sclerosis complex now requires two or more distinct types of lesions, rather than multiple lesions of the same type in the same organ system. Although diagnosis on purely clinical grounds can continue to be difficult in a few patients, there should be little doubt about the diagnosis for those individuals who fulfill these strict criteria. Couples with more than one child with tuberous sclerosis complex, no extended family history, and no clinical features of tuberous sclerosis complex are more likely to have germline mosaicism for tuberous sclerosis than nonexpression of the mutation. Germline mosaicism, while fortunately rare, will not be suspected from either diagnostic criteria or molecular testing until a couple has multiple affected children. Genetic counseling for families with one affected child should include a small (1% to 2%) possibility of recurrence, even for parents who have no evidence of tuberous sclerosis complex after a thorough diagnostic evaluation. (J Child Neurol 1998;13:624-628).

Causes of Death in Patients With Tuberous Sclerosis

Of the 355 patients with tuberous sclerosis complex (TSC) examined at the Mayo Clinic, 49 had died (9 of causes other than TSC). We attempted to determine what pattern of organ involvement occurred most often in the 40 patients who died of TSC. One baby died of cardiac failure due to cardiac rhabdomyomas, and one child died of rupture of an aneurysm of the thoracic aorta. Eleven patients died of renal disease, which was the commonest cause of death. Ten patients died as a result of brain tumors, and four patients (who were 40 years of age or older) died of lymphangiomyomatosis of the lung. Thirteen patients with severe mental handicaps died of either status epilepticus or bronchopneumonia; in all but one of these patients, the only source of information was the death certificate. Survival curves show a decreased survival for patients with TSC in comparison with that for the general population. Patients with TSC need lifelong follow-up for early detection of potentially life-threatening complications.

The spectrum and diagnosis of acid maltase deficiency

P o m p e ’ i n 1932 described generalized glycogenosis as a disease fatal in infancy. However, the recognition of acid maltase deficiency (AMD) in this disease by Hers’ in 1963 has led to the diagnosis of less severely affected cases (cases cited in Discussion). In these patients, symptoms may occur after infancy and the prognosis is better, The late-onset form of the disease may simulate, and is often misdiagnosed as, other myopathies. This paper compares the infantile, childhood and adult cases of AMD and considers the diagnostic methods.

Cortical Tuber Count: A Biomarker Indicating Neurologic Severity of Tuberous Sclerosis Complex

The relationship between the number of cortical tubers observed by magnetic resonance imaging (MRI) and the severity of cerebral dysfunction of tuberous sclerosis patients has been examined in a meta-analysis of the published literature. The literature review has identified five independent studies for examining the association. These studies consistently reveal that the cortical tuber count detected on MRI scans is increased among those with more severe cerebral disease. Severity of the cerebral dysfunction is measured by the seizure status and its control and by the developmental status and the level of mental retardation. Meta-analysis demonstrates that within a study population, the MRI-detected cortical tuber count is six times more likely to be above the median count for tuberous sclerosis patients with severe cerebral dysfunction (poor seizure control or moderate-severe retardation or both) than more mildly affected tuberous sclerosis patients. Similarly, across studies, moderately to severely affected patients are five times more likely to have greater than seven MRI-detected cortical tubers than those more mildly affected. These associations are both statistically significant and strong. The cortical tuber count is a biomarker that reasonably predicts the severity of cerebral dysfunction of tuberous sclerosis. Cortical tubers of tuberous sclerosis form in the early gestational period. The embryologic disruption determining the clinical severity of the cortical dysfunction of tuberous sclerosis is set in the early gestational period. (J Child Neurol 1997;12:85-90).

Renal Lesions in Tuberous Sclerosis

The renal lesion classically associated with tuberous sclerosis is angiomyolipoma. Renal cysts are less frequent, occurring alone or in conjunction with angiomyolipomas. We reviewed the records of 274 patients with tuberous sclerosis registered at our clinic. Of 95 patients evaluated for renal lesions 51 (54 per cent) had positive findings: 45 had angiomyolipomas, 17 had renal cysts and 11 had both lesions. These lesions usually are multiple and bilateral, and are diagnosed most effectively with computerized tomography or ultrasound. Surgery (10 kidneys) was done for life-threatening hemorrhage or suspected malignant lesions.

Subependymal Giant Cell Astrocytoma: A Clinical, Pathological, and Flow Cytometric Study

Of 345 patients with tuberous sclerosis complex evaluated at the Mayo Clinic from 1950 to 1989, 23 were identified as having brain tumors. In 20 of the 23, histological or clinical evidence showed the tumor to be a subependymal giant cell astrocytoma. A search of the Mayo Clinic tissue registry yielded 73 giant cell-containing astrocytomas and intraventricular gliomas exclusive of ependymomas. Reexamination revealed no further examples of subependymal giant cell astrocytoma in patients without features of the tuberous sclerosis complex. Considerable histological variation was observed in the 15 subependymal giant cell astrocytomas subjected to critical microscopic review. It is of note that no correlation was noted between either the histological features, such as atypia, mitoses, endothelial proliferations, necrosis, or the flow cytometric characteristics and the clinical course or the survival time of the patients.

Surgical Treatment for Epilepsy in Cerebral Tuberous Sclerosis

Summary: Tuberous sclerosis (TS) is an autosomal dominant hamartiosis and hamartomatosis with variable expression that is commonly associated with medically intractable seizures. Patients with TS complex (TSC) frequently have multiple brain lesions that can give rise to seizure activity. We report 9 patients with TSC who underwent epilepsy surgery at the Mayo Clinic between 1986 and 1990. Surgical procedures performed included cortical resection (n = 2) and stereotaxic lesionectomy (n = 7). Neuropathologic diagnoses were cortical tubers (n = 7) and glioneural hamartomas (n = 2). Three of 9 patients had multifocal interictal scalp epileptiform EEG activity; however, ictal recordings identified the focus of seizure activity, which in all cases corresponded to a prominent neuroimaging abnormality. Our patients have been followed for 10–72 months (mean 35 months). Four patients are seizure‐free with medication, 2 are seizurefree without medication, 2 had >80% reduction in seizure frequency, and 1 experienced only an initial temporary reduction in seizure frequency. Postoperative EEG recordings showed absence of epileptiform abnormalities in the 5 patients who are seizure‐free; the other 4 patients continue to have multifocal abnormalities. These data suggest that epilepsy surgery may be beneficial in selected patients with TSC despite multifocal EEG and neuroimaging abnormalities.

Risk factors for developing multiple sclerosis after childhood optic neuritis

We reviewed the records of all children (younger than 16 years of age) who presented with a diagnosis of optic neuritis (ON) identified through the comprehensive records-linkage systems at the Mayo Clinic and identified 94 cases between 1950 and 1988 with a documented history of idiopathic ON. Detailed follow-up information was available on 79 patients, with a median length of follow-up of 19.4 years. Life-table analysis showed that 13% of the 79 patients with isolated ON had progressed to clinically or laboratory-supported definite multiple sclerosis (MS) by 10 years of follow-up, 19% by 20 years, 22% by 30 years, and 26% by 40 years. Gender, age, funduscopic findings, visual acuity, or family history of either ON or MS did not predict the development of MS. The presence of bilateral sequential or recurrent ON increased the risk of developing MS (p= 0.002; hazard ratio = 5.09), whereas the presence of infection within 2 weeks before the onset of ON decreased the risk of developing MS(p = 0.060; hazard ratio = 0.24). This study of childhood ON supports the lower risk of recurrence and progression to MS compared with adults.

The neuropathy of sulfatide lipidosis (metachromatic leukodystrophy).

THE FIRST MANIFESTATIONS of sulfatide lipidosis (metachromatic leukodystrophy ) sometimes are the symptoms and signs of a peripheral neuropathy. The increased protein content of cerebrospinal fluid without pleocytosis often found in patients with this disorder resembles the albuminocytologic dissociation found in the Guillain-BarrB syndrome. The diagnosis may be overlooked until the inexorable course of the disease results in clinically detectable involvement of the central nervous system. Although rare, this disease is the most common form of 1eukodystrophy.l I t has been observed in patients of all ages, but most frequently its first symptoms appear in children before their second birthday. The clinical course varies with the age at onset.2 As Hagberg3 stated, the late infantile form of this disease begins in the second year of life, with unsteady gait, muscle weakness, and hypotonia. At this stage, myopathy, spinal muscular atrophy, or a peripheral neuropathy may be suspected. Sulfatide lipidosis is undoubtedly an important cause of polyneuropathy during the first year of life. In the first stage of the illness, it is difficult to distinguish clinically this disorder from other varieties of peripheral neuropathy or myopathy. Measurement of the conduction velocities of peripheral nerves is useful in detecting the presence of a peripheral neuropathy when signs of a peripheral nerve disorder are minimal, especially when signs of central nervous system involvement predominate. Con-

Prognosis in Sturge-Weber Disease: Comparison of Unihemispheric and Bihemispheric Involvement:

One hundred two patients with Sturge-Weber disease who were seen at the Mayo Clinic between 1942 and 1986 were studied retrospectively to determine the difference in prognosis between unihemispheric (88 patients) and bihemispheric (14 patients) involvement. Seizures occurred in 63 with unihemispheric involvement and 13 with bihemispheric; the mean age at onset of seizures was 24 months in the former and 6 months in the latter. Of the total group, 19% were severely or moderately mentally retarded, 27% were mentally retarded but educable, and 45% had average intelligence. In the bihemispheric involvement group, 46% were severely or moderately mentally retarded, 38% were retarded but educable, and only 8% had average intelligence. Bilateral involvement of the brain by Sturge-Weber disease is associated with earlier onset of seizures and worse prognosis for mental development compared with unilateral involvement. ( J Child Neurol 1988;3:181-184).