PMID- 11796775
OWN - NLM
STAT- MEDLINE
DCOM- 20020227
LR  - 20190501
IS  - 0022-3050 (Print)
IS  - 1468-330X (Electronic)
IS  - 0022-3050 (Linking)
VI  - 72
IP  - 2
DP  - 2002 Feb
TI  - Ocular motor myotonic phenomenon in myotonic dystrophy.
PG  - 236-40
AB  - OBJECTIVE: To detect disconjugate ocular motor abnormalities and a possible 
      extraocular muscle myotonic phenomenon in patients with myotonic dystrophy (MyD). 
      METHODS: The magnetic scleral search coil technique was used to record 
      monocularly the small (25 degrees ) and large (50 degrees ) saccades, which were 
      paced to two interstimulus intervals (ISIs), one short (1 s), the other long (5 
      s). The case study comprised 20 patients with MyD, 10 patients with multiple 
      sclerosis (MS), and 10 controls. The amplitude, duration, peak velocity, and 
      skewness of the velocity profile (ratio between the acceleration and the 
      deceleration periods) of each saccade were measured. The disconjugate parameters 
      (difference between the two eyes of the same measure), and the myotonic parameter 
      (the maximal (as absolute value) short-long ISI difference between the same 
      measures) were considered. RESULTS: The disconjugate parameters were the same in 
      all three groups. The mean values of myotonic parameters found in patients with 
      MyD for duration (for both small and large target displacements) and skewness 
      (for small target displacements only) differed from those found for both the MS 
      and the control groups. Additionally, the occurrence of individual patients 
      presenting with abnormal duration and skewness parameters was higher in the MyD 
      than in the MS group. In patients with MyD, the saccade duration was longer for 
      long than for short ISI; the effect derived from a prolongation of the 
      acceleration period, which manifested as an increase in skewness. CONCLUSION: The 
      results can be explained by a combination of the myotonic and the warm up 
      phenomena. A delay in the relaxation (myotonia) of the extraocular muscle may be 
      more evident after a long fixation period (long ISI) and it may improve by 
      increasing saccade pacing (short ISI-warm up). This phenomenon is slight, and is 
      unlikely to affect saccade performance significantly, but it may provide some 
      insight into the nature of the disorder affecting extraocular and skeletal 
      muscles in myotonic dystrophy.
FAU - Versino, M
AU  - Versino M
AD  - Fondazione Istituto Neurologico C Mondino, IRCCS, Dipartimento di Scienze 
      Neurologiche, Universita di Pavia, Via Palestro 3, 27100 Pavia, Italy. 
      mversino@unipv.it
FAU - Rossi, B
AU  - Rossi B
FAU - Beltrami, G
AU  - Beltrami G
FAU - Sandrini, G
AU  - Sandrini G
FAU - Cosi, V
AU  - Cosi V
LA  - eng
PT  - Journal Article
PL  - England
TA  - J Neurol Neurosurg Psychiatry
JT  - Journal of neurology, neurosurgery, and psychiatry
JID - 2985191R
SB  - IM
MH  - Adolescent
MH  - Adult
MH  - Aged
MH  - Female
MH  - Humans
MH  - Male
MH  - Middle Aged
MH  - Multiple Sclerosis/diagnosis/physiopathology
MH  - Myotonic Dystrophy/*diagnosis/physiopathology
MH  - Oculomotor Muscles/physiopathology
MH  - Oculomotor Nerve Diseases/*diagnosis/physiopathology
MH  - Reaction Time/physiology
MH  - Saccades/physiology
PMC - PMC1737732
EDAT- 2002/01/18 10:00
MHDA- 2002/02/28 10:01
PMCR- 2005/02/01
CRDT- 2002/01/18 10:00
PHST- 2002/01/18 10:00 [pubmed]
PHST- 2002/02/28 10:01 [medline]
PHST- 2002/01/18 10:00 [entrez]
PHST- 2005/02/01 00:00 [pmc-release]
AID - 10.1136/jnnp.72.2.236 [doi]
PST - ppublish
SO  - J Neurol Neurosurg Psychiatry. 2002 Feb;72(2):236-40. doi: 10.1136/jnnp.72.2.236.