Cortical Ribbon 3.0

The cortical ribbon has officially taken off! We are crossing borders, blowing minds, and as always, squeezing a corny joke or two in when we can (our editorial staff suffers from a touch of the Witzelsucht). This week we welcome back our colleagues from Tanzania, who have graciously offered to write about one of their many amazing clinical experiences (see case of the week below).

Case of the Week: Think Zebras – Global Health Neurology

Tetanus CHild

An adolescent Maasai boy seen in clinic in Northern Tanzania with classic generalized tetanic spasm or opisthotonic posturing with dramatically arched back, flexed/abducted arms, and clenched fists.  

Here’s a diagnosis you (luckily) won’t see often! Tetanus results from the contamination of a wound, typically a penetrating or puncture injury, with the anaerobic endotoxin-producing bacterium Clostridium tetani that is ubiquitous in soil. The toxin, known as tetanospasmin, travels retrograde up local peripheral nerves and enters the CNS where it blocks the release of inhibitory neurotransmitters by irreversibly degrading exocytic membrane protein synaptobrevin. This results in widespread activation of the autonomic and motor system resulting in autonomic hyperactivity (tachycardia, fever, labile pressures, sweating) and tonic skeletal muscle contraction with intense intermittent spasms. All muscle groups become involved in most cases giving rise to the classic opisthotonic posturing shown above. Muscles of the jaw, face, and head are often involved first due to their shorter axon length giving rise to trismus or lockjaw and “risus sardonicus”, the pained “sardonic smile” in patients with facial muscle spasm. Respiratory failure in the setting of thoracic or pharyngeal muscle contraction or exhaustion is the typical cause of death, though circulatory failure can also occur. Mainstays of treatment include halting toxin production with meticulous wound care and antibiotics (metronidazole) as well as neutralization of unbound toxin with the human tetanus immune globulin. The more allergenic equine antiserum is often used in developing countries and can often cause anaphylaxis.

In resource-poor settings where critical care is not available (intubation with sedation and paralysis), supportive management for spasms include long-acting benzodiazepines such as diazepam as well as other muscle relaxants including phenobarbital, chlorpromazine, and baclofen. It can take up to 6 weeks for the growth of new axonal nerve terminals and cessation of spasms. Tetanus is one of the few diseases where acute infection does NOT convey immunity, so vaccination with the full Tdap series in affected patients is paramount to preventing re-infection.

Tetanus infection is relatively rare in industrialized nations but remains a significant public health concern in many developing countries where vaccination is not as widespread. The disease is particularly prevalent and fatal in neonates who become infected at birth after contamination of the umbilical stump. Tetanus was previously so common in East Africa that the indigenous Maasai tribe routinely removed the bottom two incisors of young children so as to be able to feed them while they had lock-jaw. In the United States, the CDC reports an average incidence of ~30 cases per year in patients with insufficient vaccination. Go get those tetanus booster folks!

Pediatric Pearls: Kids Get Autoimmune Encephalitis Too!

What to say when that parent teacher conference didn’t go so well…

It’s probably NMDA. Not only do kids get it, but it’s not that uncommon! Children with NMDA encephalitis tend present more commonly with neurologic based symptoms (movement abnormalities and/or seizures) compared to adults who tend to present with psychiatric features.  Very young children, (if they do present with behavioral abnormalities) present with developmental regression, temper tantrums, or inattention. Of all of the NMDA cases, 40% occur in children younger than age 18, with young girls being 80% of these cases. There have even been reports of children as young as 8 months old!

So what does this actually look like in kids..

NMDA usually begins with a prodromal phase occurring days to weeks before symptom onset (fever, malaise, HA, URI).  This is followed by seizures, abnormal movements, and/or acute behavioral change (these are the three most common presenting symptoms in children).  Seizures are present in up to 80% of patients and the majority of anti-NMDA patients have an abnormal EEG. Hyperkinetic movements and facial automatisms (chewing, grimacing, biting movements) are VERY common in children with anti-NMDA. Dysautonomia (hyperthermia, tachycardia, HTN, urinary incontinence) is also common. MRI findings  (if present) are nonspecific and abnormal MRIs are less frequent in children.  Antibody testing is more sensitive in CSF than in serum for anti-NMDA.

Shoot. Now what?

Treatment is actually quite similar to adults. First line is usually IVIG, plasmapheresis, and/or high dose steroids.  Second line therapies include rituximab and/or Cytoxan (rarely).  Cytoxan is not frequently used in children due to side effects ( i.e. infertility, premature gonadal failure, malignancies) These kids usually require a rehab stay following hospitalization. Luckily, up to 80% of patients make a substantial or full recovery, but relapse can occur in 25% of patients (at a higher rate than adults). Check out this website to see more information and useful resources for families of patients with NMDA. Also, if you are in need of a good cry, I encourage to read about the four year old orphaned polar bear named Knut who drowned in Berlin while suffering from a wicked case of NMDA encephalitis.

The Price is Rite Review

Not All Rhythms Are Circadian – Periodic Alternating Nystagmus

This week’s Price is Rite Review comes from bedside teaching by the Eponym himself, our Dear Ray Price. Ever feel like a patient’s physical exam findings change before your very eyes? Trust those instincts. Sometimes rhythmic oscillations are from killer dance moves, sometimes they have a neurologic origin. Periodic Alternating Nystagmus (PAN) is a form of horizontal nystagmus seen during primary gaze which predictably and stereotypically changes in frequency and amplitude as well as direction! For example, the patient may have left beating nystagmus which increases in frequency and amplitude, then wanes before stopping momentarily. It then follows the exact same pattern in the opposite direction! In most cases, the nystagmus goes in one direction for 1-2 minutes before switching, therefore you must observe it for at least a few minutes to avoid being fooled. These lesions localize to the cerebellar nodula/uvula (which abuts the 4th ventricle). In cases of acquired PAN, baclofen is the agent of choice for treatment. As always, direction changing nystagmus argues towards a central etiology. We finally have a reason why the resident’s exam is so different from the attending’s…

 This is your Brain on Poetry – Weekly Neurology Haikus

Aspirin and Plavix
Attending shuts down your plan
Ask another one

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