New this month in Scientific American Medicine:

  • Myoclonus
  • The Neurologic Examination
  • Ataxias
  • Tremors
  • Constipation in the Emergency Department
  • Hernias in the Emergency Department
  • Appendicitis: Point-of-Care Ultrasonography
  • Antidote to Anticholinergic Toxicity


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Principle of jerk-locked back-averaging.

Myoclonus

HIROSHI SHIBASAKI, MD, PhD
Department of Neurology and Human Brain Research Center, Kyoto University School of Medicine, Kyoto, Japan
MARINA A.J. KONING-TIJSSEN, MD, PhD
Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands

 

Patients in the epileptic subgroup of cortical myoclonus suffer from progressive action-induced, stimulus-sensitive, multifocal or generalized myoclonus. The epileptic group is largely considered progressive myoclonus epilepsy or progressive myoclonus encephalopathy (PME). Recently, mutations in the Golgi SNAP receptor member 2 (GOSR2) gene were identified as a cause of PME or progressive myoclonic ataxia, previously known as Ramsay Hunt syndrome. All patients have a similar phenotype with progressive cortical reflex myoclonus, ataxia, generalized seizures, preserved cognition, and areflexia.

 


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Polymyositis By Jensflorian (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0) or GFDL (http://www.gnu.org/copyleft/fdl.html)%5D, via Wikimedia Commons

The Neurologic Examination

NICHOLAS J. BEIMER, MD
DOUGLAS J. GELB, MD, PhD
Department of Neurology, University of Michigan, Ann Arbor, MI

 

The directed neurologic examinations for neuromuscular disease focus heavily on the motor and sensory examinations and the cranial nerves involved in motor function, although valuable information may still be learned from other subsections of the neurologic examination. Most neuromuscular diseases do not primarily impact cognitive function, so the mental status testing included in the screening examination is usually sufficient. However, there are exceptions, such as the frontotemporal executive dysfunction that can occur in patients with amyotrophic lateral sclerosis, the generalized cognitive dysfunction that can occur in some of the muscular dystrophies, and the alteration in consciousness that can occur in association with respiratory failure due to neuromuscular weakness.

 


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Spinal cord T1–weighted magnetic resonance image, sagittal view, showing cervical spinal cord atrophy in a patient with Friedreich ataxia.

Ataxias

HÉLIO A. G. TEIVE, MD, PhD
Internal Medicine Department, Neurology Service, Ataxia Unit, Universidade Federal do Paraná, Paraná, Brazil
ORLANDO G. P. BARSOTTINI, MD, PhD
Department of Neurology and Neurosurgery, Division of General Neurology and Ataxia Unit, Universidade Federal de São Paulo, São Paulo, Brazil

 

Spinocerebellar ataxias (sCAs) are one of the primary cerebellar ataxias. A panel of experts in sCAs recently published an interesting study about the pathologic mechanisms underlying neurodegeneration in sCAs. The authors discussed several molecular mechanisms that can modulate neurodegeneration in sCAs, such as transcriptional dysregulation, protein aggregation, autophagy, ion channels, the role of mitochondria, and RNA toxicity. This new field of research could help therapeutic strategies at early stages of the sCAs.

 


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Action tremor assessment.

Tremors

ALFONSO FASANO, MD, PhD
Division of Neurology, University of Toronto, Morton and Gloria Shulman Movement Disorders Clinic and the Edmond J. Safra Program in Parkinson’s Disease, Toronto Western Hospital, Toronto, ON, Canada
GÜNTHER DEUSCHL, MD, PhD
Department of Neurology, Christian-Albrechts-University, University-Hospital Schleswig-Holstein, Kiel, Germany

 

Among the rare tremors included in this review, orthostatic tremor (OT) is a unique tremor syndrome characterized by a subjective feeling of unsteadiness during stance, eventually occurring during gait in severe cases. OT is the only tremor syndrome with a pathognomonic frequency on surface electromyography of the legs while standing. Because of its rarity, epidemiologic data are lacking. Four types of OT are summarized: primary OT, OT-plus (co-occurring with other primary neurologic disorders), symptomatic OT, and slow OT.


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Bristol Stool Scale

Constipation in the Emergency Department

JAMIE SANTISTEVAN, MD
CIARA J. BARCLAY-BUCHANAN, MD, FACEP
MARY C. WESTERGAARD, MD, FACEP
Department of Emergency Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI

 

Enemas involve instilling fluid into the colon through the rectum and work by softening the stool, distending the lumen of the bowel, and inducing colonic contractions. Enemas should be used sparingly in the treatment of constipation. They can be used after manual fecal disimpaction for bowel cleansing or to prevent impaction after several days of constipation. Sodium phosphate enemas have been associated with volume and electrolyte disturbances, including hyperphosphatemia and renal failure, and there have been several reports of death associated with their use. The use of sodium phosphate enemas should be avoided in the very young and very old because of these associated side effects.


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Point-of-care sonogram showing a ventral abdominal wall hernia.

Hernias in the Emergency Department

DANIEL BERHANU, MD
CIARA J. BARCLAY-BUCHANAN, MD, FACEP
MARY C. WESTERGAARD, MD, FACEP
Department of Emergency Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI

 

Point-of-care (POC) ultrasonography can provide real-time and dynamic imaging at the bedside to aid hernia diagnosis, and imaging may be obtained while the patient is performing actions that accentuate the hernia (i.e., Valsalva maneuver). Ultrasound imaging can differentiate between layers of muscle and fascia of the abdominal wall and provide visualization of the hernia protruding through the defect. POC ultrasonography for hernia was found to have a sensitivity of 97.8% and a specificity of 87.8% in detecting ventral hernias; additionally, ultrasonography of groin hernia has a sensitivity and a specificity of 85 to 100% and 97 to 100%, respectively.


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Appendicitis: Point-of-Care Ultrasonography

JAMES CRESWELL SIMPSON, MD
Department of Anesthesiology, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, MA
SARAH SEBBAG, MD, CM, CCFP(EM)
Emergency Ultrasound, Ochsner Health System, Department of Emergency Medicine, New Orleans, LA

 

Bedside right lower quadrant ultrasonography to assess for acute appendicitis is rapid and noninvasive and does not involve ionizing radiation. Studies have validated that nonradiologist clinicians, when trained properly, can safely and accurately perform this examination and achieve sensitivities and specificities similar to those achieved by radiologists. Whereas the specificity of the ultrasound examination is high (90 to 99%), the sensitivity is low (60 to 65%); thus, this examination is useful to rule in rather than to eliminate the possibility of appendicitis.


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Anticholinergic toxidrome.

Antidote to Anticholinergic Toxicity

Jeffrey T. Lai, MD
Department of Emergency Medicine, University of Massachusetts Medical School, Worcester, MA
Kavita M. Babu, MD
Division of Medical Toxicology, Department of Emergency Medicine, University of Massachusetts Medical School, Worcester, MA

 

Bedside right lower quadrant ultrasonography to assess for acute appendicitis is rapid and noninvasive and does not involve ionizing radiation. Studies have validated that nonradiologist clinicians, when trained properly, can safely and accurately perform this examination and achieve sensitivities and specificities similar to those achieved by radiologists. Whereas the specificity of the ultrasound examination is high (90 to 99%), the sensitivity is low (60 to 65%); thus, this examination is useful to rule in rather than to eliminate the possibility of appendicitis.


SAM-CTA

Written By

decker
The Decker Team