Pain in Chiari & syringomyelia

INTRODUCTION 

Multiple musculoskeletal (skin, muscle, joint) as well as peripheral and central nervous system structures (peripheral nerve, spinal cord, brain) are affected by Chiari I and syringomyelia and related disorders. Consequently, there are multiple types of pain syndromes that result from these structural abnormalities. While some patients experience typical headache and neck/back pains, others suffer from a combination of pain syndromes, which pose significant challenges to patients and their treating physicians. 

HEADACHE AND NECK PAIN 

The typical headache that occurs in Chiari I patients is occipital pain associated with Valsalva maneuvers (e.g. coughing, straining, lifting). The primary clinical challenge is differentiating between primary headaches such as migraine or tension headache, and headaches due to this typical posterior fossa syndrome. Obtaining a detailed history is the most important factor in sorting out the root cause of headache. Migraine is relatively common (population incidence as high as 20-30%) and so may occasionally coexist with “Chiari” headache. Nevertheless, fewer than 5% of migraine headaches are occipital in localization. The recognition of different types of headaches by the patient and physician may facilitate the selection of specific treatments.  For example, the use of triptans (see tables below) may be very effective for migraine. There are also other pharmacological and non-pharmacological approaches to the treatment of migraine and tension headache (see tables below). Joint hypermobility (and other variants of Ehlers-Danlos syndrome) is now more frequently being recognized as a cause of cranio-cervical instability, which can mimic “Chiari” headache and in some cases possibly be an associated condition. These individuals often have more widespread musculoskeletal complaints, a history of joint dislocations, as well as low blood pressure symptoms (postural orthostatic tachycardia syndrome or POTS) that can be effectively treated symptomatically. While “Chiari” headaches often resolve with posterior fossa decompression, EDS patients may worsen with standard posterior fossa decompression and may require cranio-cervical fusion surgeries. Consideration of other conditions associated with occipital headache and cerebellar tonsillar descent such as tethered cord syndrome, idiopathic intracranial hypertension, and conditions of intracranial hypotension (CSF leak syndromes) may require additional evaluation. Consideration of neurosurgical treatment strategies needs to be comprehensively evaluated in centers experienced with such conditions.  

NEUROPATHIC PAIN 

Syringomyelia and related spinal disorders as a rule are associated with multiple sensory abnormalities, including pain. As with Chiari, different types of pain can coexist in a syrinx patient. The type, location, and severity of the pain is often dictated by the spinal level affected (e.g. arms vs. legs) and the length of time that the pain has existed. The type of pain may range from disagreeable unpleasant sensations to severe, constant ongoing or episodic pain. When syringomyelia is severe or if it is left untreated for an extended period of time, this can result in a prototypical type of central neuropathic pain, meaning that the pain arises from the damaged spinal cord itself. This pain is very difficult to treat and often does not respond to surgical intervention on the syrinx or syrinx etiology. A syrinx patient may alternatively (or in addition) suffer from peripheral or radicular pain, which is more likely to respond to surgical intervention and traditional pain therapies (see table below). These 2 types of pain have different clinical manifestations and are treated very differently. Central pain is often burning, aching, constant in character, usually associated with decreased sensation in the affected dermatome on the skin. In contrast, peripheral pain tends to be sharp, sudden, lancinating, with less common sensory loss. Peripheral pain is treated with narcotics and traditional pain medications, and often will respond to surgery to remove the cause of the pain (e.g. syrinx or Chiari, nerve root compression, or peripheral nerve entrapment), while central pain requires a combination of medications designed for chronic pain therapy (e.g. tricyclic antidepressants, gabapentin, pregabalin) and non-pharmacological modalities such as physical therapy and alternative approaches (e.g. acupuncture, cognitive-behavior therapy, meditation). The longer the duration of the pain before surgery, and the more unusual is the pain (burning, associated with sensory loss, etc.), the less likely the pain will improve with surgery. If the pain is still a significant problem postoperatively, and/or it interferes with the patient’s function and quality of life, then a comprehensive pain management program including pharmacological and non-pharmacological modalities should be developed at a specialized pain center. A pain specialist is ideally suited to determine the type of pain from which the patient suffers, and provide ongoing assessment and modifications to the treatment plan over the long term.

Reviewed on 9/2019