| Paroxysmal non-epileptic events | |||
| Category | Condition | Clinical features | Investigations |
| Sleep phenomena | Benign neonatal sleep myoclonus (BNSM) | Flurries of limb myoclonia while asleep | Home video, show parents video of another child with BNSM |
| Repetitive sleep starts | Neurodevelopmentally abnormal children; runs of brief tonic episodes (spasms) (may also have epilepsy) | Video/EEG/EMG in sleep to confirm non-epileptic nature | |
| Behaviours | Tonic reflex seizures of early infancy (in otherwise normal infants) | Stiffenings when held upright especially after feeds (some resemblance to awake apnoea of Spitzer - a manifestation of gastrooesophageal reflux) | Evoke episodes on video |
| Shuddering | Transient shudders and tremors in infants or toddlers | Home video | |
| Benign non-epileptic infantile spasms (benign myoclonus of early infancy) | Runs of spasms mainly affecting upper limbs - interrupted on distraction | Video, video EEG/EMG to show lack of EEG complexes | |
| Infantile masturbation/gratification | Rhythmic repetitive thigh adduction, 'distant' or absorbed appearance often in car seat, cease with distraction | Home video | |
| Stereotypies | Often in learning disabled or autistic children, excited flapping | Home video | |
| 'Psychological' | Daydreams and non-epileptic absences | Often in school | May need EEG with hyperventilation and video, ictal EEG slowing (delta) but no spikes |
| Pseudoepileptic convulsions | Episodes when others present | Video-EEG | |
| 'Benign syncopes' | Prolonged expiratory apnoea (blue breath-holding) | Unpleasant stimuli, rapid cyanosis and opisthotonus | Home video |
| Reflex asystotic syncope | Head bump or other pain stimulus; tonic episode with spasms, often pallor but not always | If not typical, 12-lead ECG for QTc (cardiac monitoring if very severe) | |
| Vasovagal syncope | Common faint, often 'convulsive' | Head-up tilt not usually required | |
| Vagovagal syncope | Swallowing or vomiting are triggers | ECG/EEG while eating or provoked by vomiting | |
| Convulsive Valsalva | Autistic or asymbolic child; true breath-hold often follows hyperventilation | Video/audio (to hear respiratory noise then silence) | |
| 'Malignant' syncopes | Hyperekplexia | Stiff apnoeas in neonate preceded by staccato cry; nose-tap positive, startle | Video-audio; EEG/ECG/EMG (rhythmic 8-30Hz compound muscle action potentials); GLRA1 and G/yT2 gene analysis |
| 'Malignant' syncopes | Paroxysmal extreme pain disorder | Tonic episodes with flushing; often Harlequin in neonate | Video; SCN9A mutation need not be detected |
| Long-QT syndromes | Loss of consciousness, stiffness, anoxic seizure - exercise, fright, sudden sound, sleep, swimming | 12 lead ECG ± implantable ECG monitor ± ion channel gene mutation analysis | |
| Imposed upper airways obstruction | 'Seizure' or syncope in infant in presence of carer alone but shown to others (family or hospital staff] do not occur when carer not with infant | Video (covert) EEG/ECG/EMG recording of episode (covert video surveillance requires legal sanction) | |
| 'Dizzy' spells | Paroxysmal vertigo | 'Drunk' with nystagmus during episodes | Home video (ask parents to focus videocamera on child's eyes) |
| Paroxysmal torticollis | Lateral head tilt | Home video. (CACNA1A studies not required) | |
| More prolonged in Sandifer syndrome and in cervical dystonia | If episodes prolonged, gastrointestinal studies | ||
| Craniocervical junction disorder | Falls, brief stiffness, headache | MRI especially sagittal for Chiari J and upper cord | |
| Alternating hemiplegia | Alternating hemiplegia of childhood | Tonic episodes, nystagmus often monocular/eye deviations onset first 3 months, then alternating hemiplegia (limp or dystonic), may be precipitated by bathing always relieved by sleep, later fixed choreoathetosis | Home video. No more extensive investigations if history not difficult |
| Benign familial alternating hemiplegia | Autosomal dominant family history: hemiplegia arises from sleep in otherwise normal children | Home video | |
| Moyamoya | Transient hemipareses, migrainous headaches, paroxysmal dyskinesia or torticollis | 'Re-build-up' on EEG after hyperventilation (but avoid hyperventilation if moyamoya known). Brain MRI/MRA | |
| Cataplexies | Narcolepsy-cataplexy | Joke-induced; collapses, face and neck muscles first to go. No loss of consciousness (children also have excessive daytime sleepiness) | Video. Sleep latency test ± human leukocyte antigen ± CSF hypocretin |
| Niemann-Pick type C | Usually but not always defect in vertical gaze | Video, abdominal ultrasound for subtle splenomegaly, plasma chitotriosidase, bone marrow for sea-blue histiocytes, fibroblast culture for cholesterol studies | |
| Cataplexies | Paraneoplastic hypothalamic syndrome | May also have narcolepsy and other neurological features | Body imaging for occult neural crest tumour |
| Syndromes with dominant cataplexy: Prader-Willi, Coffin-Lowry, etc. | Family history or syndromic phenotype | Home or hospital video | |
| Episodic ataxias | Episodic ataxia type 1 (EA1) | Infantile 'cerebral palsy', myokymia, brief staggers | Video, surface EMG for myokymia. KCN1A mutations |
| Episodic ataxia type 2 (EA2) | Vomiting, prolonged unsteadiness, nystagmus + smooth pursuit disruption, acetazolamide-responsive | Video, MRI for vermis atrophy. 31P-MRS shows increased pH in cerebellum, reversed by acetazolamide. CACNA1A mutations possible but time-consuming | |
| Other episodic ataxias | Various neurological accompaniments | Include testing for GLUT1 deficiency (fasting blood and CSF glucose with lactate) and mitochondrial investigations | |
| Paroxysmal dyskinesias | Paroxysmal kinesigenic dyskinesia (PKD) | Dyskinesia (choreoathetosis/ dystonia) at onset of movement | Video |
| PKD in hypotonic/dystonic young male child ± ocular wobble ± MRI delayed myelination | Dystonia provoked by passive movements or lifting the child | Thyroid function: ↑ freeT3, ↓ free T4. MCT8 testing | |
| Paroxysmal dyskinesias | Paroxysmal non-kinesigenic dyskinesia | Unprovoked episodes of dyskinesia | Video. (Myofibrillogenesis regulator 1 gene involved) |
| Paroxysmal exertional dyskinesia | Various dyskinesias during strenuous exercise (may also have epileptic seizures; see Chapter 3.15) | Glucose transporter \ deficiency tests (fasting, blood and CSF glucose); echinocytes may rarely be seen on blood film | |
| Psychogenic dyskinesias | Psychogenic movement disorders cease with distraction if the child does not think he or she is being observed | Share video with movement disorder expert if in doubt | |
| Benign tonic upgaze | Intermittent tonic upgaze in infancy | Video. (No need for neurotransmitter or CACNA1A studies) | |
| Benign tonic downgaze | Especially in newborn infants | Intermittent tonic downgaze in normal neonate | Video. Head ultrasound would be wise |
| Night terrors | 1-2 (-3) total in early part of the night | Sleep video (best with infrared) | |
Source:
Mary D. King, 2009. A Handbook of Neurological Investigations in Children. 1 Edition. Mac Keith Press.
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