Australian X disease See Murray Valley encephalitis
A. Fulfils criteria for migraine with aura
5. A minimal sleep latency test that demonstrates mean sleep latency of less than 10 minutes
C. Associated features include at least one of the following:
1. Gasps, grunts or choking during sleep, 2. Frequent body movements, or 3. Cyanosis during sleep.
D. Polysomnographic monitoring demonstrates:
1. Central apneic pauses 10 seconds (20 seconds in in-fancy) in duration, and one or more of the following:
2. Frequent arousals from sleep associated with the ap-neas,
3. Brady-tachycardia, or
4. Oxygen desaturation in association with the apneic episodes, with or without
5. A minimal sleep latency test that demonstrates mean sleep latency of less than 10 minutes.
E. Other sleep disorders can be present, e.g., periodic limb movement disorder, obstructive sleep apnea syndrome, or central alveolar hypoventilation syndrome.
Adapted from the ASDA Diagnostic Classification Steering Committee.
The International Classification of Sleep Disorders Diagnostic and Coding Manual. Rochester, MN: American Sleep Disorders Association, 1990. Reproduced by kind permission of the American Academy of Sleep Medicine.
central syndrome Downward displacement of the upper brainstem at the junction with the diencephalon through the tentorial opening, leading to an orderly se-160 CENTRAL PAROXYSMAL POSITIONAL NYSTAGMUS
quence of events that witness the functional disturbance of progressively more caudal levels of the brainstem.4466 These include reduction in conscious level and Cheyne-Stokes respirations (diencephalic stage); midposition fixed pupils, loss of oculocephalic reflexes, and central neurogenic hyperventilation (pontine stage); decorti-cate posturing, ataxic or no respirations, bradycardia, and hypertension (medullary stage); and ultimately death.
central tapetoretinal degeneration See Behr disease.
central tegmental tract Fibers that descend from the red nucleus and elsewhere in the lower diencephalon and mesencephalon, running to the ipsilateral olive. It was first described by von Bechterew in 1885. Bilateral lesions of the tract appear to induce the phenomenon of palatal myoclonus.
central vestibular nystagmus See vestibular nys-tagmus.
central vestibular vertigo That form of vertigo caused by lesions of the vestibular nuclei or of the vestibulocerebellum, and characterized by change in direction with gaze to either side. The nystagmus may be pendular and can be purely horizontal, vertical, or rotatory.
central-distal axonopathy Axonal damage in the pe-ripheral extremities of axons within the CNS, one cause of which is prolonged low-level exposure to acrylamide, an industrial polymer, while the effects of MPTP, clio-quinol, and lathyrism and possibly the biochemical deficits underlying Friedreich ataxia and hereditary spastic paraplegia are others.
The clinical syndromes produced include the suba-cutely evolving onset and evolution of sensorimotor/
autonomic peripheral neuropathy, spasticity, optic at-rophy, and cerebellar ataxia.5549 See also subacute myelo-opticoneuropathy.
centrencephalic epilepsy The term applied to the supposed site of origin of generalized tonic-clonic seizures, based on the fact that bilateral epileptic dis-charges can be set up in homologous areas of the two hemispheres following stimulation of subcortical struc-tures such as the intralaminar thalamic nuclei of ex-perimental animals.
In 1938 Penfield considered that one area in the nervous system functions to integrate the electrical ac-tivity of the two hemispheres, probably the rostral brainstem and thalamus, and that this area also consti-tuted the neural substratum of consciousness.
Abnormal discharges in this region would give rise to those seizures that Penfield labeled centrencephalic.
However, it is notable that lesions of other parts of the brain may also induce seizures with exactly the same clinical and electrographic characteristics. See absence seizures.
centrencephalic myoclonic-astatic epilepsy (infan-tile myoclonic petit mal, centrencephalic myoclonic-astatic petit mal, true myoclonic epilepsy) Forms of myoclonic-astatic epilepsy for which there is no de-tectable pathological basis. In such cases there is fre-quently a positive family history of seizures.1497The pa-tient may be mentally normal or retarded, and first exhibits symptoms usually in the second to fifth years of life. Myoclonic and atonic seizures, absences, petit mal status, tonic seizures, etc. are the usual phenotypes.
See akinetic seizures, juvenile myoclonic epilepsy of Janz, centrencephalic epilepsy.
centrencephalic myoclonic-astatic petit mal See centrencephalic myoclonic-astatic epilepsy.
centrifugal (Lat, center fleeing from) Movement of a phenomenon (such as sensory loss in developing peripheral neuropathy) from proximal to distal parts of the body.
centrifugal nerve A motor nerve.
centripetal (Lat, center seeking) Movement of a phenomenon (such as sensory loss in developing pe-ripheral neuropathy) from distal to proximal parts of the body.
centripetal nystagmus A form of gaze-evoked nys-tagmus that increases with prolonged eccentric gaze, but may reverse in direction if the position of the eyes is maintained longer. It is most commonly seen in oc-ular myasthenia gravis3318or in diseases of the cere-bellum.
See also rebound nystagmus, in which nystagmus in the opposite direction occurs when the eyes are re-turned from the deviated to the primary position.
centrocecal scotoma A scotoma that involves the area of the visual field subtended between the macula and the blind spot. It reflects pathology affecting the fibers run-ning to the optic nerve head from the macula and from the retina between the macula and the optic disk.
centronuclear myopathies (myotubular myop-athies) Sporadic or variously inherited congenital my-opathies with occasional onset in childhood or adult life, characterized by the presence of structures resem-bling fetal myotubes and central nuclei in the extrafusal muscle fibers with predominance and hypotrophy of type I fibers.1744,5115The most common form maps to Xq27–q28, but autosomal dominant and recessive forms are also recorded.
Among these there is a high proportion of histo-chemical type 2 fibers resembling myotubes (with a pe-ripheral ring of myofibrils and a central area in which myofibrillar components and nuclei are present). Type 1 fiber atrophy and the nonspecific features of myopa-thy are other common findings.3985,5294
Clinically, the appearances vary; facial, extraocular, and limb weakness with equinovarus deformity of the CENTRONUCLEAR MYOPATHIES 161
feet and, in adults, a syndrome of moderate limb-gir-dle weakness have both been associated with these biopsy appearances, although a syndrome of nonpro-gressive myopathy with weakness of the facial and ex-traocular muscles and hypotonia is a characteristic presentation. Muscle pain and stiffness after exertion with relief by rest are other common symptoms.
It is possible that centronuclear myopathies and type 1 fiber atrophy with central nuclei are forms of the same disease.535
Variant members of the class include X-linked reces-sive centronuclear (myotubular) myopathy (OMIM 310400), a fatal congenital myopathy presenting with weak fetal movements, fetal distress, respiratory distress in the neonate, proximal myopathic weakness, hypoto-nia, and atrophy. Tubular aggregates are found in mus-cle biopsy specimens.5160The responsible gene maps to Xq28.5741
Centronuclear myopathy with type 1 fiber atrophy and myotubules is a slowly progressive form of centronu-clear myopathy with onset in childhood, affecting the muscles of the pelvic girdle and legs, in which the mus-cle biopsy reveals type 1 fiber atrophy, central numus-clei, and fibers resembling myotubes.535
Another variant is a form in which type 1 fiber hy-potrophy and fingerprint inclusions are found in muscle biopsy specimens. The clinical syndrome includes slowly progressive muscular weakness and features of Malins syndrome.4175
A dominantly inherited form presents in youth or adult life with proximal muscle wasting, with the facial, extraocular, and distal muscles sometimes being in-volved as well. The condition is slowly progressive and can be compatible with a normal life span. Muscle biopsy shows central nuclei with a clear surrounding zone in 60% of the fibers, for both types 1 and 2.3774
In other dominantly or recessively inherited forms pre-senting in childhood or adult life, proximal muscle weakness and wasting with sparing of the cranial mus-cles, with calf muscle hypertrophy567 or with car-diomyopathy, have been reported.
centrotemporal epilepsy See benign childhood epilepsy with centrotemporal spikes.
centrum ovale infarcts Stroke from acute infarction in the centrum ovale which receives its blood supply from the superficial (pial) middle cerebral artery (MCA) system through perforating medullary branches that course toward the lateral ventricles.632
centrum semiovale The hemispheric mass of gray and white matter that remains at the top of the brain-stem when the cerebrum is removed. It comprises the basal ganglia and internal capsules.
cephalaea An ancient term for a form of headache resembling migraine.
cephalalgia (Gr, the head pain) Headache.
Cephalalgia The organ of the International Head-ache Society, devoted to the topic of headHead-ache and re-lated pains. Web site: www.cephalalgia.org.
cephalgia fugax See benign paroxysmal cranial neuralgia.
cephalic (Gr, pertaining to the head).
cephalic bellows sound A cranial bruit heard best over the anterior fontanelle of children with hydro-cephalus and raised intracranial pressure. It was de-scribed first in 1833 by Dr. John Dix Fisher (1797–
1850), a physician in Massachussetts,2209who thought the sound indicated the presence of cerebral pathology, but it was dismissed by Osler as being without patho-logical significance in 1880.
cephalic index A craniometric sign, the breadth of the head divided by the length and multiplied by 100, the product having no known significance.
cephalic tetanus (Rose tetanus, Rose-Villar syn-drome) A form of tetanus affecting the facial or ocu-lomotor muscles.
cephalitis An ancient term for inflammation of the brain and its membranes.
cephalocele Herniation of the intracranial contents through a defect in the skull. Such midline craniocere-bral cystic defects result from failure in the normal de-velopment of the neural tube and consist of meningo-celes, within which there is no neural tissue, and encephaloceles proper, in which some neural tissue is present.3773 They are classified as primary (occipital, parietal, sincipital, and basal) and secondary (follow-ing surgery or trauma or with a craniofacial cleft).1307 cephalohematoma (Gr, head blood a mass) A blood clot lying beneath the scalp but outside the cra-nium, seen most often in infants as a complication of a traumatic delivery.
cephalo-oculocutaneous telangiectasia See Louis-Bar syndrome.
cephaloponia (Gr, head pain) An ancient term for a severe or heavy pain in the head.
cephalosyndactyly See Waardenbeng syndrome.
CERAD The Consortium to Establish a Registry for Alzheimer Disease, a research group formed in the United States to standardize examination techniques, facilitate cooperative study, and perform annual as-sessments on a defined population.3998The Web site is acessible through http://www.alz.washington.edu/
ceradrt.html.
CERAD Global Deterioration Scale (GDS) A rating instrument for staging the magnitude of cognitive and functional impairment in normal aging, age-associated memory impairment, and primary degenerative de-mentia, composed of a battery of tests designed to pro-162 CENTROTEMPORAL EPILEPSY
vide brief and accurate assessment of the presenting symptoms. The levels of cognitive functioning are rated from no cognitive decline to very mild, moderate, mod-erately severe, severe, and very severe decline, and for each of these, full notation of definitions are given.3998 CERAD test battery A selection of tests designed to provide a brief and accurate assessment of the present-ing manifestations and cognitive changes in patients with Alzheimer disease or other cognitive disorders in the elderly.
Aside from information on demographics, a drug in-ventory, and history, physical and general neurological examinations are performed and a diagnostic impres-sion recorded. Tests of verbal fluency, the modified Boston Naming Test, the Mini-Mental State Examina-tion, tests of constructional praxis, word lists to recall, and word list recognition tests are also adminis-tered.3997
ceramidase deficiency See Farber disease.
ceramide lactoside lipidosis (ceramidosis) See Far-ber disease.
cerebellar abscess A purulent collection within the cerebellum, usually associated with pyogenic inflam-mation of the middle ear.
Clinically, headache, vomiting, drowsiness, ataxia of gait and limb movements, nystagmus, meningism, and evidence of increased intracranial pressure are the lead-ing features.
cerebellar ataxia (ataxy, Zappert syndrome) 1. An inclusive term for all the clinical motor manifestations of cerebellar disease, especially incoordination or awk-wardness in the performance of a motor task due to disease of the cerebellum or its connections.
The term thus begs the question; “What are the signs of cerebellar disease?” Although an experienced clini-cian may have no doubt that certain mild abnormali-ties of voluntary movements are due to loss of cerebel-lar coordinating functions, no precise differentiation between these abnormalities and those caused by e.g., proprioceptive disorders or subtle weakness from cor-ticospinal lesions is possible, other than by the exclu-sion of such alternatives by determining that the other signs of such lesions are not to be found. All of the tests to elicit “cerebellar signs” (discoordination, dysmetria, dysdiadochokinesis, etc.) may in fact be abnormal on the basis of frontal lobe, internal capsule, or other path-way lesions.
2. (cerebellar ataxias, spinocerebellar ataxias) Inher-ited diseases of the cerebellum or of its connections, presenting with typical signs of cerebellar dysfunction and frequently complicated damage to other parts of the nervous system. These are distinguished here from those conditions that have no known hereditary basis, which are classified here.
A recent comprehensive classification of the
multi-tude of the inherited cerebellar ataxias is that of Hard-ing,2440who defined five groups, to which the condi-tion of hereditary spastic paraparesis may be added conveniently. Chart C–9 is based upon that classifica-tion, adapted and with the addition of syndromes taken from the extensive listing by Baraitser335and others.
Chart C–9. The Idiopathic Dominantly Inherited Ataxias
ADCA Type I
These are late-onset (usually after 20 years) ataxias with variable added signs. A compilation from various sources2407,4952,5403and from Dr. Will Garrett, personal communication, follows.
Spinocerebellar ataxia type 1 (SCA1) Autosomal dominant form with a locus on chromosome 6p22–p23. Clinically, gait disturbance and speech problems are the typical on-set symptoms, developing usually in the twenties; oph-thalmoplegia, optic atrophy, pyramidal and extrapyra-midal signs, peripheral sensorimotor neuropathy, mild dementia, and amyotrophy follow. This is the most fre-quent single example of the SCAs reported to date.4260a A CAG repeat has been incriminated.
SCA2 Autosomal dominant form on 12q23–q24.1.4083a Clinically, this resembles SCA1 but the hyporeflexia is more pronounced, saccades are particularly slow, and both myoclonus and cramps are reported.437In variant forms, there is also Parkinsonism2347or retinal degener-ation.461
SCA3/Machado-Joseph disease Autosomal dominant form on 14q24.3–q32.1 I. This dominantly inherited syndrome with onset usually in mid-adult life comprises progres-sive ataxia and supervening pyramidal signs, dysarthria, and vertical gaze pareses associated with cerebellar and brainstem atrophy with perioral fasciculations. Optic at-rophy, chorea, parkinsonism, dystonic or rigid dystonias, distal weakness and wasting, and retained reflexes are common additional findings; saccade velocities are not reduced in some kinships. The responsible gene maps to 6p24–p23.2440,5015The condition was first described in detail by Menzel in 1891.3839See also Joseph disease.
SCA4 Located on 16q24.ter or 16q22.1. A form with promi-nent sensory axonal neuropathy and hyporeflexia but without eye movement disorders.1881a
SCA12 Located on 5q31–33. This autosomal dominant syn-drome is characterized clinically by action tremor in the head and arms with onset in the fourth decade of hyper-reflexia and mild to moderate cerebellar signs such as ataxia, dysmetria, and dysarthria. Parkinsonism and de-mentia have been recorded later in life.4221The syndrome results from an unstable CAG repeat in the gene PPP 2R2B.
ADCA Type II: Ataxia with Pigmentary Retinal Degeneration/Progressive Macular Degeneration
Clinically, the cerebellar syndrome is accompanied by pro-gressive visual loss and evidence of anterior horn cell degen-eration. It is mapped to 3p12–p21.11654
SCA7 Located on 3p12–13 11. This syndrome, resembling SCA1 with onset usually in childhood, comprises pro-gressive visual failure (maculopathy), ataxia, seizures, and supervening gaze pareses. Pyramidal signs including hy-CEREBELLAR ATAXIA 163
perreflexia, posterior column sensory loss, and dementia are also reported. The syndrome is associated with at-rophic changes in the cerebellum, basal ganglia, and spinal cord.2236,5894This must be the same condition as that formerly called ADCA II: with pigmentary retinal de-generation/progressive macular degeneration.
ADCA Type III: “Pure” Cerebellar Ataxias with Late Onset (Adult-onset cerebellar ataxia, olivopontocerebellar atrophy, parenchymatous cerebellar cortical atrophy, cerebellopontine atrophy, late cortical cerebellar atrophy, Marie-Foix Alajoua-nine syndrome, Thomas atrophy) This group of ataxic disor-ders is of unknown etiology with onset usually after the age of 50 years.2438Corticospinal, extrapyramidal, and ocular fea-tures are not prominent and sensory loss is absent. The chief pathological change is cerebellar cortical atrophy with loss of the Purkinje cell layer.179,2605
SCA5 Located on 11q13 (11 cen). This form presents as a slowly developing cerebellar and pyramidal syndrome in the third decade, with global cerebellar atrophy.4589a SCA6 Located on 19p13. This dominantly inherited form
re-sembles SCA5 but is manifested in older adults and poste-rior column function is impaired. Life span is normal.
Downbeat nystagmus is an added feature but the brainstem is otherwise unaffected. The mutation is allelic with episodic ataxia type 21997,2079,5347and linked to familial hemiplegic migraine both clinically and through shared abnormalities of the CACNA1A P/Q type calcium channel ␣1subunit.
SCA8 Located on 13q21. This is a slowly progressive form with cerebellar, pyramidal, and cognitive signs.2897 SCA11 Life span is normal. This form is not yet mapped.
Others
SCA9 Located on a chromosomal site not yet determined.
SCA10 Located on 22q13. This pure cerebellar syndrome has seizures as an added feature, and is described from Mexico.4606 A similar phenotype has been mapped to 22q.13.3704
SCA13 Located on 19q. This recessive form manifests in childhood. Psychomotor failure is reported.
SCA14 Located on 19q
SCA 15 (Unknown locus) This pure ataxic syndrome is re-ported in a single Australian family.5371
SCA16 Autosomal dominant form on 8q 22.1–24.1. Head and hand tremors are reported.
SCA17 Not completely characterized.
Dentato-rubro-pallido-luysian atrophy (DRPLA) Lo-cated on 12 p
SCA types 1, 2, 3, 6 and 7, 12, and DRPLA stem from mu-tations consisting of expanded and unstable CAG trinucleotide repeats. SCA8 results from an expansion of a CTG trinu-cleotide repeat. The types of mutations responsible for SCA4 and 5 and for SCA9 through 11 are unknown.5403See also Ramsay Hunt syndrome; mitochondrial diseases.
ADCA Type IV
Cerebellar signs with myoclonus and deafness characterize ths group (see Chart C–10) which may not be a distinct entity.
See May-White syndrome below, and MERRF.
Chart C–10. The (Spino)Cerebellar Ataxias III. Congenital inherited ataxias
A. Congenital ataxia with mental retardation with or without spasticity (includes pontoneocerebellar and granule cell hypoplasia); which are autosomal reces-sive or dominant, or X-linked. The various syndromes identified include the following:
Angelman syndrome
Ataxia with photomyoclonus A dominantly inherited syndrome characterized by extreme sensitivity to light, and with myoclonus, cerebellar ataxia, ataxic gait, pes cavus, kyphosis, and dementia.1625 The condition may also manifest later in life. This con-dition and MERRF (Myoclonus Epilepsy with Ragged Red Fibers) are probably the same.
Cerebellar hemisphere hypoplasia (congenital granular cell hypoplasia) A syndrome of ataxia and mental retardation, each of variable severity.5957
Congenital ataxia with choroidal coloboma (Pfeiffer syndrome)
Congenital cerebellar atrophy A dominantly inherited syndrome in which ataxia complicates early mild motor delay.1994
Lhermitte-Duclos disease (granular cell hypertrophy) Neonatal cerebellar atrophy with retinal dystrophy A fatal syndrome of neonatal ataxia with retinal dys-trophy and limitation of joint movement compli-cated by diarrhea, vomiting, pericardial effusion, and hepatic fibrosis.
Olivopontocerebellar atrophy with hepatic cirrhosis and retinal dystrophy A congenital inherited ataxic syn-drome with cerebellar hemisphere hypoplasia, char-acterized by pericarditis, neonatal feeding problems, hypotonia, pigmentary retinopathy, abnormal en-larged liver, joint contractures, and mental and de-velopmental delay.337
Paine syndrome
Pontocerebellar hypoplasia
Progressive ataxia, retinal degeneration, peripheral neu-ropathy, myopathy, and mental subnormality A rare congenital syndrome in which the above manifesta-tions are accompanied by hypoparathyroidism, dwarfism, malabsorption and cholelithiasis.2181 NARP syndrome (Neuropathy, Ataxia and Retinitis Pigmentosa).
B. Joubert syndrome (congenital ataxia, recessively