Mitochondrial diseases mimicking neurotransmitter defects.
OBJECTIVE
Mitochondrial disorders are clinically heterogeneous. We aimed to describe 5 patients who presented with a clinical picture suggestive of primary neurotransmitter defects but who finally fulfilled diagnostic criteria for mitochondrial disease.


METHODS
We report detailed clinical features, brain magnetic resonance findings and biochemical studies, including cerebrospinal fluid (CSF) biogenic amine and pterin measurements, respiratory chain enzyme activity, and molecular studies.


RESULTS
The 5 patients had a very early onset age (from 1 day to 3 months) and a severe clinical course. They all showed a clinical picture suggestive of infantile hypokinetic-rigid syndrome (hypokinesia, hypomimia, slowness of reactions, tremor), other abnormal movements (myoclonus, dystonia), axial hypotonia, limb hypertonia, feeding difficulties, and psychomotor delay. Abnormal CSF findings among the 4 patients without treatment included low levels of homovanillic acid (HVA) in 3 patients, with associated low 5-hydroxyindoleacetic acid (5-HIAA) concentrations in two of them. Absent or mild and transitory improvement was observed after treatment with L-dopa. A diagnosis of mitochondrial disorder was finally made due to the appearance of hyperlactacidemia, diverse respiratory chain defects, and multisystemic involvement.


CONCLUSIONS
Secondary neurotransmitter disturbances may occur in mitochondrial diseases. Differential diagnosis of hypokinetic-rigid syndrome presenting in infancy could also include paediatric mitochondrial disorders.
Neurology Department, Hospital Sant Joan de Deu, Passeig Sant Joan de Deu, 2, 08950 Esplugues, Barcelona, Spain. agarcia@hsjdbcn.org
Angels
A
Garcia-Cazorla
Sofia
S
Duarte
Mercedes
M
Serrano
Andres
A
Nascimento
Aida
A
Ormazabal
Ines
I
Carrilho
Paz
P
Briones
Julio
J
Montoya
Rafael
R
Garesse
Pere
P
Sala-Castellvi
Mercedes
M
Pineda
Rafael
R
Artuch
D000409:Alanine / Q000097:blood; D001921:Brain / Q000000981:diagnostic imaging; D002675:Child, Preschool; D003241:Consanguinity; D003937:Diagnosis, Differential; D015259:Dopamine Agents / Q000627:therapeutic use; D004421:Dystonia / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000188:drug therapy*; D042967:Electron Transport Complex I / Q000235:genetics / Q000378:metabolism; D042963:Electron Transport Complex II / Q000235:genetics / Q000378:metabolism; D014450:Electron Transport Complex III / Q000235:genetics / Q000378:metabolism; D005260:Female; D006719:Homovanillic Acid / Q000134:cerebrospinal fluid; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000134:cerebrospinal fluid; D007223:Infant; D007231:Infant, Newborn; D019344:Lactic Acid / Q000097:blood; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D028361:Mitochondrial Diseases / Q000134:cerebrospinal fluid / Q000175:diagnosis* / Q000473:pathology*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011622:Pterins / Q000032:analysis; D011859:Radiography; D016896:Treatment Outcome
D015259:Dopamine Agents; D018377:Neurotransmitter Agents; D011622:Pterins; D019344:Lactic Acid; D007980:Levodopa; D006897:Hydroxyindoleacetic Acid; D042963:Electron Transport Complex II; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III; D000409:Alanine; D006719:Homovanillic Acid