Rare Diseases in Neurology
Rare neurological conditions can seem relatively common to neurologists because, like many specialists, they often get referrals from general practitioners or other neurologists. Many neurologists also become specialists in certain rare diseases. For example, a neuroimmunologist may tend to get referrals for people suspected of having multiple sclerosis (MS), only to determine they have another condition such as neuromyelitis optica.
Rare diseases that show up regularly in a neurologist’s office include autoimmune conditions (eg, transverse myelitis, optic neuritis, vascular myelopathy, acute disseminated encephalomyelitis), rare seizure types, musculoskeletal disorders (eg, amyotrophic lateral sclerosis [ALS], Duchenne muscular dystrophy, spinal muscle atrophy), and developmental conditions (eg, Batten disease, Charcot-Marie-Tooth disease), as well as a host of conditions that often manifest themselves with neurological symptoms (eg, Fabry disease).
Once a patient with a rare condition receives a proper diagnosis, the patient and their family usually experience great relief, because an accurate diagnosis of a rare condition can be so challenging and slow. In many cases, a patient will spend years going from specialist to specialist being misdiagnosed and having their symptoms attributed to anything from depression, aging, or a sleep disorder to neuropathic pain, MS, or lupus. In other cases, the neurologist may be the first specialist contacted to properly diagnose a disease in a patient (ie, children with seizures).
The years-long periods patients can go without a correct diagnosis can be the result of many factors, including a “no-fault error” (misdiagnosing a rare disease that mimics a more common one), a “system error” (not having the equipment or tests available to properly diagnose or suspect a rare condition), or a “physician cognitive error” (diagnosing a rare condition as an atypical form of a common condition). However, once a correct diagnosis is made, most patients feel relief and vindicated after having gone from specialist to specialist for so long. Often, these patients want to give back to the rare disease community and/or the specialty center by giving of their time and effort, donating blood, volunteering for clinical studies, filling out surveys, etc.
Neurological diagnostic tests and procedures:
List of rare conditions:
List of FDA-approved orphan drugs:
Treatment for a neurological condition will either be on-label—often involving a very expensive orphan drug—or off-label, for which there may or may not be evidence about its effectiveness. An on-label medication should be the preferred treatment since it has been approved to be safe and effective for the rare neurological condition. Examples of such orphan drugs include:
Clobazam (Onfi) for Lennox-Gastaut syndrome
Vigabatrin (Sabril) for infantile spasms
Droxidopa (Northera) for dizziness in people with neurogenic orthostatic hypotension
Tetrabenazine (Xenazine) for chorea associated with Huntington’s disease
Gabapentin enacarbil (Horizant) for post-herpetic neuralgia
Although a limited number of orphan drugs are approved for neurological conditions, many orphan drugs are in development. A small sample of phase 3 clinical trials underway for rare neurological conditions include the following:
ALS: cannabis extract, olanzapine, phrenic stimulation
Batten disease: gene therapy
Charcot-Marie-Tooth disease: physical therapy
Dravet syndrome: cannabidiol, clobazam
Neuromyelitis optica: MEDI-551, eculizumab, SA237
Sturge-Weber syndrome: cannabidiol, everolimus
Advocacy Support and Information
In the world of rare conditions, patients and their families quite often have strong, informative resources available in the form of advocacy groups. These groups can also be valuable to clinicians seeking information about a rare disease. For a complete list of advocacy groups, see Appendix B of this resource guide. Some related to neurological conditions are below:
Batten Disease Support and Research Association:
Fabry Support and Information Group:
Fibromuscular Dysplasia Society of America:
Guthy-Jackson Charitable Foundation, which funds neuromyelitis optica research:
Hereditary Neuropathy Foundation:
Transverse Myelitis Association: