Progressive myoclonic epilepsy as an adult-onset manifestation of Leigh syndrome due to m.14487T>C

BACKGROUND

m.14487T>C, a missense mutation (p.M63V) affecting the ND6 subunit of complex I of the mitochondrial respiratory chain, has been reported in isolated childhood cases with Leigh syndrome (LS) and progressive dystonia. Adult-onset phenotypes have not been reported.

OBJECTIVES

To determine the clinical-neurological spectrum and associated mutation loads in an extended m.14487T>C family.

METHODS

A genotype-phenotype correlation study of a Belgian five-generation family with 12 affected family members segregating m.14487T>C was carried out. Clinical and mutation load data were available for nine family members. Biochemical analysis of the respiratory chain was performed in three muscle biopsies.

RESULTS

Heteroplasmic m.14487T>C levels (36-52% in leucocytes, 97-99% in muscle) were found in patients with progressive myoclonic epilepsy (PME) and dystonia or progressive hypokinetic-rigid syndrome. Patients with infantile LS were homoplasmic (99-100% in leucocytes, 100% in muscle). We found lower mutation loads (between 8 and 35% in blood) in adult patients with clinical features including migraine with aura, Leber hereditary optic neuropathy, sensorineural hearing loss and diabetes mellitus type 2. Despite homoplasmic mutation loads, complex I catalytic activity was only moderately decreased in muscle tissue.

INTERPRETATION

m.14487T>C resulted in a broad spectrum of phenotypes in our family. Depending on the mutation load, it caused severe encephalopathies ranging from infantile LS to adult-onset PME with dystonia. This is the first report of PME as an important neurological manifestation of an isolated mitochondrial complex I defect.

The X-linked infantile spasms syndrome (MIM 308350) maps to Xp11.4-Xpter in two pedigrees

We report 2 families with X-linked infantile spasms syndrome (X-linked West syndrome). Data from clinical examination, biochemical analysis, neuroimaging, and neuropathology are discussed. In these families, genetic linkage analysis was able to locate the disease gene to the distal part of the short arm of the X chromosome, between Xpter and Xp11.4. This is the first report of linkage with genetic markers in this disorder. Although most cases are sporadic, further unraveling of the genetic background of the familial cases might greatly improve our understanding of infantile spasms.

Dementia paralytica in a fifteen-year-old boy

A 15-year-old boy, whose history revealed an unremarkable pregnancy, birth and neonatal period and who had shown a normal motor and mental development, presented at the hospital with deterioration of cognitive functions since the age of 7. He was bedridden with manifest ataxia involving all limbs, anisocoria and a sluggish to absent pupil reaction to light. Syphilis serology was positive with a Venereal Disease Research Laboratory (VDRL) titer of 1:256 and a Treponema pallidum Haemagglutination Assay (TPHA) titer of 1:163840. Cerebrospinal fluid (CSF) protein concentration was 55 mg/dl and CSF-leucocyte count was 14/mm3 (85% mononuclear cells). CSF-VDRL-titer was 1:16. A diagnosis of congenitally acquired dementia paralytica was made, since the boy's parents' clinical exam and serology results were suggestive for latent syphilis. Although cognition was still very much deteriorated five months following penicillin treatment, clinical examination revealed partial recuperation. Screening for syphilis should be part of routine testing in every subject presenting with cognitive deterioration, regardless of age.

Single photon emission computed tomography using perfusion tracers in seizure disorders

Single photon emission computed tomography (SPECT) using perfusion tracers makes it possible to estimate regional cerebral blood flow (rCBF) and, indirectly, local brain metabolism. It may be possible to detect and follow physiopathological alterations, such as may be seen in seizure disorders. The authors review the principles of and some data on perfusion SPECT in seizure disorders, stress advantages as well as major drawbacks and add their initial experience with Tc-99m hexamethylpropyleneamine oxime (HMPAO) SPECT in febrile convulsions.

Technetium-99m hexamethylpropylene amine oxime single photon emission tomography in febrile convulsions

We report our initial experience with technetium-99m hexamethyl propylene amine oxime (99mTC-HMPAO) brain single photon emission tomography (SPET) in the investigation of 19 children presenting with febrile convulsions. Two patients with complex febrile convulsions showed focal SPET lesions contralateral to the neurological deficit. However, in 9 out of 17 patients with simple febrile convulsions, focally disturbed perfusion was shown. In 4 out of 6 patients with electroencephalogram (EEG) abnormalities on admittance, SPET revealed at least 2 focal lesions. The temporofrontal region was the one most commonly involved. The SPET findings presented here also suggest a temporal relationship with the febrile convulsions, with markedly fewer lesions if examined after 12 days. In our initial experience, perfusion SPET did not show any particular pattern helpful in the differential diagnosis of the child presenting with febrile convulsions. Physiopathologically, our findings may support the hypothesis that brain tissue is regionally more vulnerable to fever, in patients presenting with febrile convulsions.

Epidural abscess causing tetraparesis: case report

A case is presented of a 26-year-old male with a 8-day history of fever and back pain, and limb weakness beginning 24 hours before admission. An abscess caused by a staphylococcus aureus was localised in the thoracic paravertebral region with penetration in the subarachnoidal space at T1. Myelography appeared to be superior to CAT-scan and NMRI of the cervico-thoracal region in supporting the diagnosis. Treatment by laminectomy of C7-T3 48 hours after admission did not lead to neurological improvement and an incomplete tetraplegia persisted. The importance and difficulty of early diagnosis is stressed.