Motor neuropathy contributes to crouching in patients with Dravet syndrome.
Since SCN1A is expressed in the motor neuron initial segment, we explored whether motor neuron dysfunction could contribute to gait disturbance and orthopedic misalignment in patients with Dravet syndrome due to SCN1A mutations.



We assessed 12 consecutive patients who presented to our institution between January and March 2013. All of them were older than 2 years and were positive for the SCN1A mutation. We performed nerve conduction velocity studies and needle EMG recordings.



We included 4 females and 8 males aged 2 to 17 years (median 7.5 years). All 12 patients showed gait disturbance regardless of age. Tendon reflexes were decreased in 4 of 12 patients. None presented cerebellar signs such as tremor, dysmetria, or adiadochokinesia. Nerve conduction study was normal or nearly normal in all patients, but EMG showed features of chronic denervation. Motor neuropathy/neuronopathy was definite in 7 patients and probable in 3.



SCN1A mutations may alter axonal function, causing motor neuropathy/neuronopathy. This may contribute to gait disturbance and orthopedic misalignment, which is characteristic of patients with Dravet syndrome.
From the Departments of Pediatric Neurology (C.G., N.C., C.B., I.D., M.H., C.C., R.N.) and Pediatric Neurophysiology (C.G., N.C., S.Q.-R.), and Reference Center for Rare Epilepsies (N.C., C.C., O.D., R.N.), Necker Enfants Malades Hospital, APHP, Paris; INSERM U1129-Infantile Epilepsies and Brain Plasticity (N.C., C.C., O.D., R.N.), Paris; Paris Descartes (N.C., C.C., O.D., R.N.), Sorbonne Paris Cité University; CEA (N.C., C.C., O.D., R.N.), Gif sur Yvette; Department of Pediatric Neurology (S.Q.-R.), Raymond Poincaré Hospital, APHP, Garches; and Paris Descartes University (C.G., I.D., R.N.), France. cyril.gitiaux@aphp.fr.
Cyril
C
Gitiaux
From the Departments of Pediatric Neurology (C.G., N.C., C.B., I.D., M.H., C.C., R.N.) and Pediatric Neurophysiology (C.G., N.C., S.Q.-R.), and Reference Center for Rare Epilepsies (N.C., C.C., O.D., R.N.), Necker Enfants Malades Hospital, APHP, Paris; INSERM U1129-Infantile Epilepsies and Brain Plasticity (N.C., C.C., O.D., R.N.), Paris; Paris Descartes (N.C., C.C., O.D., R.N.), Sorbonne Paris Cité University; CEA (N.C., C.C., O.D., R.N.), Gif sur Yvette; Department of Pediatric Neurology (S.Q.-R.), Raymond Poincaré Hospital, APHP, Garches; and Paris Descartes University (C.G., I.D., R.N.), France.
Nicole
N
Chemaly
From the Departments of Pediatric Neurology (C.G., N.C., C.B., I.D., M.H., C.C., R.N.) and Pediatric Neurophysiology (C.G., N.C., S.Q.-R.), and Reference Center for Rare Epilepsies (N.C., C.C., O.D., R.N.), Necker Enfants Malades Hospital, APHP, Paris; INSERM U1129-Infantile Epilepsies and Brain Plasticity (N.C., C.C., O.D., R.N.), Paris; Paris Descartes (N.C., C.C., O.D., R.N.), Sorbonne Paris Cité University; CEA (N.C., C.C., O.D., R.N.), Gif sur Yvette; Department of Pediatric Neurology (S.Q.-R.), Raymond Poincaré Hospital, APHP, Garches; and Paris Descartes University (C.G., I.D., R.N.), France.
Susana
S
Quijano-Roy
From the Departments of Pediatric Neurology (C.G., N.C., C.B., I.D., M.H., C.C., R.N.) and Pediatric Neurophysiology (C.G., N.C., S.Q.-R.), and Reference Center for Rare Epilepsies (N.C., C.C., O.D., R.N.), Necker Enfants Malades Hospital, APHP, Paris; INSERM U1129-Infantile Epilepsies and Brain Plasticity (N.C., C.C., O.D., R.N.), Paris; Paris Descartes (N.C., C.C., O.D., R.N.), Sorbonne Paris Cité University; CEA (N.C., C.C., O.D., R.N.), Gif sur Yvette; Department of Pediatric Neurology (S.Q.-R.), Raymond Poincaré Hospital, APHP, Garches; and Paris Descartes University (C.G., I.D., R.N.), France.
Christine
C
Barnerias
From the Departments of Pediatric Neurology (C.G., N.C., C.B., I.D., M.H., C.C., R.N.) and Pediatric Neurophysiology (C.G., N.C., S.Q.-R.), and Reference Center for Rare Epilepsies (N.C., C.C., O.D., R.N.), Necker Enfants Malades Hospital, APHP, Paris; INSERM U1129-Infantile Epilepsies and Brain Plasticity (N.C., C.C., O.D., R.N.), Paris; Paris Descartes (N.C., C.C., O.D., R.N.), Sorbonne Paris Cité University; CEA (N.C., C.C., O.D., R.N.), Gif sur Yvette; Department of Pediatric Neurology (S.Q.-R.), Raymond Poincaré Hospital, APHP, Garches; and Paris Descartes University (C.G., I.D., R.N.), France.
Isabelle
I
Desguerre
From the Departments of Pediatric Neurology (C.G., N.C., C.B., I.D., M.H., C.C., R.N.) and Pediatric Neurophysiology (C.G., N.C., S.Q.-R.), and Reference Center for Rare Epilepsies (N.C., C.C., O.D., R.N.), Necker Enfants Malades Hospital, APHP, Paris; INSERM U1129-Infantile Epilepsies and Brain Plasticity (N.C., C.C., O.D., R.N.), Paris; Paris Descartes (N.C., C.C., O.D., R.N.), Sorbonne Paris Cité University; CEA (N.C., C.C., O.D., R.N.), Gif sur Yvette; Department of Pediatric Neurology (S.Q.-R.), Raymond Poincaré Hospital, APHP, Garches; and Paris Descartes University (C.G., I.D., R.N.), France.
Marie
M
Hully
From the Departments of Pediatric Neurology (C.G., N.C., C.B., I.D., M.H., C.C., R.N.) and Pediatric Neurophysiology (C.G., N.C., S.Q.-R.), and Reference Center for Rare Epilepsies (N.C., C.C., O.D., R.N.), Necker Enfants Malades Hospital, APHP, Paris; INSERM U1129-Infantile Epilepsies and Brain Plasticity (N.C., C.C., O.D., R.N.), Paris; Paris Descartes (N.C., C.C., O.D., R.N.), Sorbonne Paris Cité University; CEA (N.C., C.C., O.D., R.N.), Gif sur Yvette; Department of Pediatric Neurology (S.Q.-R.), Raymond Poincaré Hospital, APHP, Garches; and Paris Descartes University (C.G., I.D., R.N.), France.
Catherine
C
Chiron
From the Departments of Pediatric Neurology (C.G., N.C., C.B., I.D., M.H., C.C., R.N.) and Pediatric Neurophysiology (C.G., N.C., S.Q.-R.), and Reference Center for Rare Epilepsies (N.C., C.C., O.D., R.N.), Necker Enfants Malades Hospital, APHP, Paris; INSERM U1129-Infantile Epilepsies and Brain Plasticity (N.C., C.C., O.D., R.N.), Paris; Paris Descartes (N.C., C.C., O.D., R.N.), Sorbonne Paris Cité University; CEA (N.C., C.C., O.D., R.N.), Gif sur Yvette; Department of Pediatric Neurology (S.Q.-R.), Raymond Poincaré Hospital, APHP, Garches; and Paris Descartes University (C.G., I.D., R.N.), France.
Olivier
O
Dulac
From the Departments of Pediatric Neurology (C.G., N.C., C.B., I.D., M.H., C.C., R.N.) and Pediatric Neurophysiology (C.G., N.C., S.Q.-R.), and Reference Center for Rare Epilepsies (N.C., C.C., O.D., R.N.), Necker Enfants Malades Hospital, APHP, Paris; INSERM U1129-Infantile Epilepsies and Brain Plasticity (N.C., C.C., O.D., R.N.), Paris; Paris Descartes (N.C., C.C., O.D., R.N.), Sorbonne Paris Cité University; CEA (N.C., C.C., O.D., R.N.), Gif sur Yvette; Department of Pediatric Neurology (S.Q.-R.), Raymond Poincaré Hospital, APHP, Garches; and Paris Descartes University (C.G., I.D., R.N.), France.
Rima
R
Nabbout
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004576:Electromyography; D004831:Epilepsies, Myoclonic / Q000235:genetics* / Q000503:physiopathology*; D005260:Female; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D009154:Mutation; D062550:NAV1.1 Voltage-Gated Sodium Channel / Q000235:genetics*; D009431:Neural Conduction / Q000502:physiology
D062550:NAV1.1 Voltage-Gated Sodium Channel; C568242:SCN1A protein, human