Posts about neurology from 2 of our recent medical students

drexel_medicine_white_coat_2012

 

Posted by Ilya Grinberg:

Last week I participated in the MDA clinic and there was one patient who really stuck out in my mind. He was a 17 year old male who had Duchenne Muscular Dystrophy. He was completely wheelchair-bound and could barely move any of his extremities. This obviously meant that he was completely reliant on people to take care of him and that he could not participate in the day to day activities that a normal person could. He was also starting to have breathing difficulty and probably would need to start therapy on a ventilator soon too.

DMD is an x-linked recessive disorder that affects boys from an early age. It affects 1 out of 3600 boys so it is not too uncommon. The disease is due to a mutation of the structural protein Dystrophin which is normally found in all muscles. The protein is found on the X chromosome which explains why it is an X-linked disease. Patients are usually born normally but will start gradually developing symptoms during the first few years of life. The first observations are usually progressive muscle weakness in proximal muscles in addition to muscle atrophy. One of the key clinical signs in DMD is calf psuedohypertrophy which occurs due to fibrosis of the necrotic muscle tissue. Another common finding that presents early on is Gower’s sign, where the patient uses his arms to stand up due to weakness in the proximal leg muscles.

Click here to find out more about DMD.

 

Posted by John Soliman:

What is Neurology one may ask? Prior to and during medical school I feel like the exposure to the study of neurology was very limited. Interaction between neurological patients and medical professions was far and few between. I have had little encounters with the realm that lies ahead. Prior to starting the clerkship I was very intimidated due to my lack of knowledge and ignorance. I can say jokingly I barely knew how to spell Neurology. Even the basics of neurology such as anatomy was daunting usually getting hung up on learning one part or area as seen in this video. I have to say I had something in common with Pinky.

After the 4 weeks of neurology I have realized that neurology covers a broad realm of knowledge and information on the central and peripheral nervous system.

During my clerkship I was lucky enough to be exposed to many patients encountering a lot of this medical conditions and problems. I was able to identify and correlate symptoms with disease states and vice versa.

The most memorable experience was the MDA clinic. I was able to meet and was integrated into the care of a lot of the Myotonic dystrophy patients. I was able to see hear their day to day life experience, talk to their care givers and be able to help with their care. After seeing patients like this it really brought “problems” Into perspective. The amazing thing was the broad range of how these medical conditions affect each individual differently.

I had the opportunity to see two brothers who are both affected with Myotonic Dystrophy. One brother can walk, talk and act normal with minimal weakness while the other was wheel chair bound. Talking to them brought home how a muscular dystrophy can affect the lives of affected individuals. Myotonic dystrophy is an autosomal dominant genetic process which means it can affect 50% of the carriers offspring. This may affect a family’s decision on having kids both mentally and psychologically. In this specific case, one of the brothers and his wife decided to adopt children due to the high risk of having a child with myotonic dystrophy. Dealing with something like this is a full time job on its own so it can be draining mentally, physically and financially on families.

Overall the experience has been great as I have gotten to see patients with medical conditions that I may not be able to see again. This clerkship has been knowledgeable and I has encountered a broad real of neurology that I never had experienced in the past.

Click here to find out more about Myotonic Dystrophy.

Click here to find out more about MDA Clinic at Monmouth.

Exon Skipping for Duchenne Muscular Dsystrophy

There was some exciting data presented at MDA’s 2014 clinical Conference held this week in Chicago regarding gene therapy for Duchenne muscular dystrophy (DMD).

What is exon skipping?

skimming_stones

Many cases of DMD are caused by small deletions in the dystrophin gene which lead to frame shifts and totally disrupt transcription:

If you imagine that the gene is made up of segments (or exons) which ultimately spliced together to make a recipe or message for producing the protein:

exon-skipping-scheme

A deletion of exon 71 would be considered “in frame” because the 70 and 72 could still joint up and allow transcription.  However, a deletion of exons 48 through 50 would be “out of frame” since 47 and 51 do not splice back together to form the message:

exon

The message would become corrupted and the gene product, in this case dystrophin, would be dysfunctional or even totally absent:

frameshift

The drug Eteplirsen will link 47 and 51 back together again, and in so doing restore the reading frame and facilitate transcription of an altered but hopefully functional gene product:

exon skiip

Does it work?

A clinical study started in August 2011

The preliminary results from this study were very encouraging – the boys who received the drug maintained strength and walking ability and there were no treatment related adverse effects.

What’s the next step?

Gene therapy trial for Duchenne Muscular Dystrophy

dmd

Duchenne and Becker muscular dystrophy are both caused by mutations in the same dystrophin gene.

How it this possible?

Well, the genetic code which is translated to from proteins “talks” in words made of three letters (base pairs).

dmd dna

A gene mutation that deletes only one or two base pairs, or worse still signals the end of the word (known a “premature stop codon”) will result it a very abnormal dysfunctional gene product, leading to complete deficiency of functioning dystrophin, and the more severe Duchenne Muscular Dystrophy.

dmd muscle bx

Normal muscle bx (a) vs Duchenne muscular dystrophy (b) with complete absence of dystrophin (d)

However a gene mutation (deletion) that removes base pairs in a multiples of three is called an in-frame mutation, and causes a (sometimes only minor) qualitative change in the dystrophin protein, leading to the milder Becker’s muscular dystrophy.

Ataluren (also known as PTC124) is a small molecule designed to overcome premature stop codons.

alturen

Put simply, the idea is that it might convert some Duchenne boys in to a milder form (more like Becker’s) of muscular dystrophy by allowing them to produce some more normal dystrophin.

The drug can only help boys affected with premature stop codons confirmed by DNA testing.

The drug is currently undergoing Phase III trialsClick here for more information.

STIFF PERSON SYNDROME: A misleadingly flippant name for a serious disease

SPS1

Posted by Jennifer Ding, MSIV Drexel University College of Medicine

What is Stiff Person Syndrome (SPS)?

exaggerated lumbar spine

Exaggerated lumbar lordosis in SPS

Stiff Person Syndrome (yes, the official moniker) is a very rare autoimmune disease of the nervous system that affects maybe 1 in 1,000,000 people worldwide. Most patients experience fluctuating, involuntary muscle rigidity in the trunk and limbs, an exaggerated lumbar curve, and a heightened sensitivity to their environment.

Loud or unexpected noise, touch and emotional distress can actually set off muscle spasms or even falls in those afflicted.

Attacks of spasms are usually unpredictable, last for minutes and tend to recur over hours. These spasms can be so intense that they actually can cause.

The rigidity seen in SPS is characterized by a stiffness (hence the name) that begins over several months along the spine and spreads to the legs. In the lucky few, the fluctuating rigidity becomes fixed leading to difficulty walking, bending, and frequent falling.

Who gets SPS?

Moersch and Woltman first described SPS in 1956 based on 14 cases that were observed over 32 years. It was initially called “stiff man syndrome” before the disease was found in females and children as well.

Today, we see that SPS affects twice as many women as men and is frequently associated with other autoimmune diseases, such as Diabetes Mellitus Type 1, thyroiditis and vitiligo. Age of onset varies between 30 to 60 with it occurring most frequently in people in their 40s.

What causes SPS?

Now for the science behind SPS: like any autoimmune disease, the problem is thought to lie with antibodies that attack the body’s own cells or enzymes. Patients with SPS have antibodies against glutamic acid decarboxylase (GAD), an enzyme, that produces gamma-aminobutyric acid (GABA), a chief inhibitory neurotransmitter (a chemical) that plays a crucial role in regulating our central nervous systems. GABA is also directly involved in regulating muscle tone.
Mechanism

The exact details of the way GAD antibodies cause SPS remain unknown. Many people with GAD antibodies don’t develop SPS. But most patients with SPS have a high level of GAD antibodies in their blood as well as antibodies that inhibit GABA-receptor-associated-protein (GABARAP). Therefore, scientists hypothesize that the root cause of the muscle rigidity and spasms seen in SPS lie in a GABA impairment.

Think of it this way: muscles work in pairs. When one contracts, the other relaxes, and vice versa. GABA is key in regulating this relaxation and without it, both muscles end up contracting. When both muscles contract, they lose the ability to work together, leading to a stalemate, or stiffness that we see in patients with SPS.

How is SDS diagnosed?

The level of GAD antibodies can be measured in the blood and cerebrospinal fluid (CSF). As aforementioned, the mere presence of GAD antibodies in the blood does not directly correlate with a diagnosis of SPS. Instead, the higher the level of GAD antibodies in the blood, the more likely SPS is the diagnosis.

Electromyography (EMG) can also be used to demonstrate involuntary neuronal firing in muscles.

How is SPS treated?

While there is no cure for SPS to date, there are treatment options that are aimed at symptom relief. Benzodiazepines, such as Valium (diazapam) or Ativan (lorazepam), that act similarly to GABA are the primary treatment for symptom relief. These drugs have muscle relaxant and anticonvulsant effects. Baclofen, another type of GABA-agonist that is dispensed from an implanted pump, can be used as a muscle relaxant. Neurontin (gabapentin) is a seizure medication that has also been used for symptom relief. However, SPS tends to worsen over time, leading to patients requiring increased dosages of drugs.

Intravenous immunoglobulin (IVIG) that target the antibodies themselves are also used in patients with advanced disease. IVIG has been shown to decrease stiffness and the heightened startle reflex. Steroids, rituximab, and plasma exchange have also been used to target the immune system in SPS patients, but the benefit of these treatments remains unclear.

Additional reading material

Click here for more information on SPS, the most up-to-date research on the neurological disease, and social networking for those interested, afflicted, or who have family members who are afflicted.

Click here for an article about a patient with SPS.


News segment about a young dancer with SPS.

Plasma Exchange For Myasthenia Gravis

Posted by Christopher Orr,  Drexel University College of Medicine 2014

Ms. AB presented last week in the Neurology office with shortness of breath and weakness, and she knew it was from her myasthenia gravis.

She was already on an anticholinesterase inhibitor, but it was very apparent that she was suffering from a severe exacerbation of myasthenia gravis.

We sent her to the Emergency Room in order to be admitted so she could receive plasmapheresis in order to minimize the antibodies that were blocking the acetylcholine receptors at her neuromuscular junctions.

To give a brief history of Ms. AB’s myasthenia gravis, she was diagnosed in the Fall of 2013 when she presented with muscle weakness and difficulty breathing.  She was treated with plasmapheresis during that initial episode, and improved.

In the interim, she had also been given steroids to reduce the immune response of her autoantibodies towards her acetylcholine receptors, but this actually caused increased leg weakness, more likely from steroid myopathy than myasthenia gravis.

Unfortunately she experienced another exacerbation in December, and she was treated with intravenous immunoglobulin (IVIG).  What is interesting is that when she was treated with IVIG, her symptoms did not improve as they had done plasmapheresis.

There is limited research on the efficacy of IVIG in comparison to plasmapheresis in the literature.  A comparison study of IVIG vs. plasmapheresis waspublished by Mandaway et. al. in the Annals of Neurology in 2010 and included 1,606 patients – both therapies showed similar clinical outcomes in terms of both mortality and complications.  From a purely financial perspective, IVIG was more cost effective because of lowered length of stay and total inpatient charges.

However, a smaller study published by Stricker et. al. in JAMA in 1993 reported 4 patients who did not respond to initial IVIG treatment but later responded to plasmapheresis.  There were no definite prognostic factors mentioned that might explain why plasma exchange may be better than IVIG in certain patients.  The article stated further research was needed.

Ms. AB did present with myasthenia gravis at a later age of onset than is typically observed.  For future studies that compare IVIG to plasmapheresis, I would be highly interested in a subgroup analysis on a patient’s age and the efficacy of the 2 treatment modalities of IVIG and plasmapheresis.

When we saw Ms. AB in the hospital, she was already doing much better with plasmapheresis.  In addition, we were For the future, Ms. AB would likely be discharged to a rehabilitation facility and there are considerations to start her on CellCept (mycophenolate mofetil).  It would be preferential to start the patient on CellCept as an immunomodulatory drug to decrease the autoantibodies against her acetylcholine receptors and reduce her need for plasmapheresis.

I chose to write a reflection on Ms. AB for 2 reasons.  First, she and her husband are both very kind people, and it is a pleasure to see her improve.  Second, I love technology in medicine and healthcare.  When we saw Ms. AB’s plasmapheresis treatment, it was fascinating to see the apparatus that was using centrifugal force to spin her blood and separate her plasma from the WBCs, RBCs, and platelets.  The mechanism behind performing the plasmapheresis was to take off her plasma, which had the autoantibodies, and replace new plasma with albumin.  Please look below to see a picture of a plasmaphresis apparatus and an explanation of how it works.  After my experience seeing Ms. AB, it was a pleasure to treat her and learn from her condition.

OLYMPUS DIGITAL CAMERA

Pictured above is an apparatus that is used for the plasmapheresis treatments.  Although this machine may seem very intimidating, it operates on the basis of how spinning blood can separate the blood into different components, such as the plasma, RBCs, WBCs, and platelets. To explain in a simple manner, a central venous line is obtained from the patient so blood can be brought to the machine and spun.  After the plasma is removed by the centrifugal force, the remaining components (RBCs, WBCs, and platelets) is added with albumin and saline (a protein found in plasma) then reintroduced into the patient.

In many instances, diseases can be complicated to comprehend.  I wanted to give a better understanding of myasthenia gravis.  I hope this picture and caption that I included make the disease easier to digest.

nmj achr

The above image shows the synapse of a neuromuscular junction.  In a healthy patient, the acetylcholine can bind the acetylcholine receptor and produce a response in the muscle.  In a patient with myasthenia gravis, the antibody (shown in green) is blocking the acetylcholine receptor and preventing the acetylcholine in the synapse from reaching the muscle.  This picture is a good educational tool because it also shows how the treatment of pyridostigmine (Mestinon) can improve a patient’s symptoms.  The acetylcholinesterase (AChE, the red pac-man figure) is what degrades the acetylcholine in the synapase.  Pyridostigmine is an anticholinesterase inhibitor and impedes the red pac-man figure in the picture from working.  Therefore, pyridostigmine increases the amount of acetylcholine in the synapse that can reach the receptor and will improve the symptoms in an episode of myasthenia gravis.

Duchenne Muscular Dystrophy

Posted by Elliot Dubowitch from Drexel University College of Medicine Class of 2014

Duchenne muscular dystrophy (DMD) is one of the four main groups  of muscular dystrophy, a muscle disorder that affects and weakens the musculoskeletal system.

Muscular dystrophies are genetically inherited and progressive.

DMD is inherited in an x-linked manner.  This means that the mother, who is unaffected, is a carrier for the disease and has a 50% chance of passing it on to her male children.

The disease is caused by a deficiency in the Dystrophin protein, a complex that anchors the muscle to surrounding tissue.

dystrophin

This disease has a wide spectrum of symptom severity, depending on the type of genetic mutation, with Duchenne being very severe, and Becker’s muscular dystrophy being much more mild.

The symptoms in DMD are not usually present at birth.  As the child ages, however, they symptoms will gradually become worse and worse.  Most children are unable to walk by thirteen years of age and die in their twenties due to respiratory failure.

One of the earliest signs of DMD is called to as the “Gower Maneuver.”  Although not pathognomonic for DMD, this maneuver is a sign for proximal muscle weakness and is often correlated with DMD.  Below is a clip of a child performing to Gower’s maneuver to stand.  The patient must “walk” up his body using his hands from a sitting position due to weakness in his hip and thigh muscles.  Below is a video clip demonstrating this.

Another early sign is calf pseudohypertrophy.  Although the muscle looks bigger, it is not necessarily stronger, as the functional muscle is replaced by nonfunctional fibrous tissue.

Unfortunately, there is currently no cure for DMD.  However, there is symptomatic treatment available, such as respiratory support, cardiovascular monitoring and treatment and (if needed) surgery for scoliosis.

Steroids are the only current medication that has been shown to keep the boys walking longer.  A study was conducted in which one group of boys were given steroids daily, whereas the other group of boys were given steroids 10 days on and 10 days off.  The boys receiving daily steroids walked on average until the age of 14.5 year, while the boys receiving steroids intermittently walked to only 12 years of age.  The boys receiving continuous steroids also had more side effects including weight gain, mood swings, increase risk of infection, and other side effects of steroid usage.  If one is to consider steroid use, it is imperative to remember that it must be used at the time the child is still ambulating.  The boy will not regain lost function, however he may retain his current function longer.  In the future we hope that new drugs like VBP-15 will hopefully provide the benefits of corticosteroids without some of the side effects.

Genetic research is currently being done to hopefully find a cure for this disease.