The function of cerebral blood vessels and their connection to thunderclap headaches in cervical spine instability

Ross Hauser, MD.

A thunderclap headache is a very specific diagnosis. If you are reading this article you are likely looking for more information regarding yours or a loved one’s challenge with this problem as you may have reached the point of having had many tests to rule out a potential life-threatening situation and there are no answers for you. Initially you may have been told, after all your tests, that this may have been a one-time event. That you are reading this article indicates that this has occurred more than once for you. Your management plan may now include managing these episodes as they come along for the rest of your life.

People stories:

We have seen many patients who describe “the worst headache I have ever had.” A headache that comes on without warning and is so intense it typically leads to emergency room visits and ultimately a “hurried” CT scan or brain MRI.

Here are two stories:

Chronic headaches, neck pain, and foggy head. I have always suffered from headaches but have experienced “thunderclap headaches” twice over the past year, leading to an ER visit the first time. I receive chiropractic adjustments but only experience temporary relief. My sister has POTS/dysautonomia – and I question if I don’t have the same issues.

While doing pushups, I felt a “pop” at the base of my skull, followed by thunderclap headache “worst headache of my life.” It went away after two minutes. Three days later, I was riding stationary bike and 4 minutes in a second thunderclap headache occurred. I couldn’t talk or barely walk. I was tested for idiopathic intracranial hypertension. I am On diamox now for the last year and a half with minor pulsatile tinnitus, but mostly severe tinnitus 24/7 with some hearing loss. I am struggling to find someone to listen to the issues I’m having.

I am going to start this article for you the reader with the understanding that standard and even emergency testing has already been performed following a first time episode of a thunderclap headache and that a visit to the emergency room or other types of urgent care services has ruled out a life-threatening or very serious immediate situation. You have been designated as someone with Idiopathic Thunderclap Headache – you have your headaches from a mostly unknown cause.

Cervical instability induced Thunderclap headache

Sudden headache with severe intensity that comes on and peaks within a minute.
Common with subarachnoid hemorrhage. (Bleeding in the space that surrounds the brain).
When brain MRIs are normal or non-diagnostic, the vascular component can be diagnosed by angiography or transcranial Doppler ultrasound.
Caused by reversible cerebral vasoconstriction syndrome
Brain blood vessels constrict temporary brain ischemia
Can lead to focal neurological deficits and stroke.
Cause can be cervical instability. (Why symptoms are intermittent and sudden.)

Reversible Cerebral Vasoconstriction Syndrome and Posterior reversible encephalopathy syndrome

In this section we will concentrate one aspect to the cause of symptoms. Cervical spine instability. But first, let’s look at the anatomy Posterior reversible encephalopathy syndrome and Reversible Cerebral Vasoconstriction Syndrome.

Doctors at Emory University School of Medicine published their findings centered around a case history of a common cause to Posterior reversible encephalopathy syndrome and Reversible Cerebral Vasoconstriction Syndrome. The case appears in the Journal of stroke and cerebrovascular diseases.(4)

The authors write: “Posterior reversible encephalopathy syndrome and Reversible Cerebral Vasoconstriction Syndrome are two increasingly recognized entities that share similar clinical and imaging features. Posterior reversible encephalopathy syndrome is characterized by vasogenic edema (edema which mainly affects the brain’s white matter coming from leaks and fluid buildup from capillaries) predominantly in the parieto-occipital regions (this area of the brain is involved in processing and understanding language, reading and writing, the ability to tell where objects are in space, calculation, working memory, face and object recognition), associated with acute onset of neurological symptoms including encephalopathy (altered mental capacity or state), seizures, headaches, and visual disturbances.

Reversible Cerebral Vasoconstriction Syndrome is characterized by reversible segmental and multifocal vasoconstriction of the cerebral arteries and classically presents with thunderclap headache, with or without associated focal neurological deficits and seizures. Posterior reversible encephalopathy syndrome is frequently associated with uncontrolled hypertension but can also be seen in the setting of renal failure, exposure to cytotoxic agents, or pre-eclampsia (Pregnancy complication.) Posterior reversible encephalopathy syndrome and Reversible Cerebral Vasoconstriction Syndrome share precipitating factors, clinical and radiological features, and frequently co-exist, suggesting a common pathophysiological mechanism related to reversible dysregulation of cerebral vasculature (cerebral blood flow), endothelial dysfunction, and breakdown of the blood-brain barrier.”

In the above paper we have a discussion of blood vessels, endothelial dysfunction, and breakdown of the blood-brain barrier. Are these issues that can be traced to cervical spine instability?

The function of cerebral blood vessels and their connection to thunderclap headaches in cervical spine instability

The function of cerebral blood vessels are maintained by signals mainly supplied by sympathetic nerves arising from the superior cervical sympathetic ganglion. While the superior cervical sympathetic ganglion innervates the head, the carotid plexus (a network of sympathetic nerves) runs parallel to the carotid artery into the head. If upper cervical instability interrupts the superior cervical sympathetic ganglion’s electrical output, the results on human health could therefore be devastating. Some authors call the sympathetic superior cervical ganglia “little neuroendocrine brains,” as they provide sympathetic innervation to the hypothalamus, pineal gland, cephalic blood vessels, choroid plexus, eye, myocardium, carotid body, and the salivary and thyroid glands. Removal of the superior cervical ganglia can cause loss of vasoconstriction control of brain and pituitary blood vessel, changes in cerebrospinal fluid production from the choroid plexus, and other central effects in response to partial sympathetic denervation. The input from the superior cervical sympathetic ganglion is necessary to maintain not only the blood-brain barrier, but also cerebral blood flow.

What are we seeing in this image?

This is the superior cervical sympathetic ganglion in its native habitat. Surrounded by blood vessels (internal carotid artery and internal jugular vein) and nerve networks and near the C2 vertebrae. When the vertebrae wander out of position, it takes these veins, arteries, nerves, and nerve bundles with it, causing compression and stretching of these vital structures. In the context of this article, this compression and stretching can not only cause pain but disrupt nerve signals causing neurologic-like symptoms and conditions already outlined in this article.

Symptoms and treatments of Thunderclap headache

A March 2020 paper in the Journal of neurology (1) discusses thunderclap, cough, exertional and sexual (orgasm) headache.

These are a group of paroxysmal (sudden, seizure like – coughing attacking) and precipitated (unexpected onset) headaches, which often occur in bouts with prolonged remissions. Each can occur in primary and secondary (in reaction to another event, like sex) form.
Indometacin (an Nonsteroidal anti-inflammatory drug NSAIDs) seems to be the most effective preventative.
Thunderclap headache is the most frequently reported headache syndrome associated with a secondary pathology. (Headaches are a symptom of, not the primary cause of patents health concern).

Several treatment types for Thunderclap headache

In the medical publication STAT PEARLS (5) housed at the National Center for Biotechnology Information, U.S. National Library of Medicine an April 30, 2022 update on treatment is offered.

Calcium channel blockers: Nimodipine is most commonly used for the treatment of a thunderclap headache.
Analgesics and anti-inflammatory drugs: Acetaminophen and NSAIDs (nonsteroidal anti-inflammatory drugs). Indomethacin has been found to be most effective. Etoricoxib is effective in prophylaxis.
Beta-blocker: Propranolol is effective in preventing a thunderclap headache and has been widely used as a prophylactic agent.
Topiramate and lithium: According to studies, in lower dosages, these medications help prevent an episode of thunderclap headache and can be safely used for prophylaxis.

Treatment Trigger Points: A Thunderclap headache after bowel movements non-responsive to medications. Doctors find cause in the temporal muscles.

A cervical spine structural cause of thunderclap headache or Reversible Cerebral Vasoconstriction Syndrome is one possibility. In December 2019, doctors published a case history in the journal Medicine (2) about a 42-year-old woman.

A 42-year-old female patient complained of a severe throbbing headache with a Numeric Rating Scale (NRS) score of 10 after bowel movements. The pain subsided temporarily after treatment with diclofenac 75 mg and Tridol 50 mg propacetamol 1 g, but the headache returned upon defecation; soon after, the patient complained again of regular headaches at 4 to 6-hour intervals without having a bowel movement as being the many driver of the headache.

The doctors performed a brain computed tomography (CT) and head and neck magnetic resonance angiography while the patient had the headache. The tests revealed no specific neurological findings. Blood analysis was also normal. Head and neck CT angiography, performed one month after the start of the headaches, revealed Reversible Cerebral Vasoconstriction Syndrome.

Treatments began – did not help

The doctors treated the patient with pregabalin (150 mg), oxycodone HCl/naloxone (10/5 mg), Alpram (0.5 mg), milnacipran (25 mg), and frovatriptan 25 mg, but there was no improvement in the headaches.

Trigger point injections

Myofascial (muscle pain) trigger points are tender areas in muscles that cause tight muscles and spasms. Equally tight muscles may cause trigger points. Some patients may be diagnosed with myofascial pain syndrome.

In this story, the 42 year-old-woman received bilateral trigger point injections in the temporal muscles (the muscles of the skull above the jaw) on four occasions at the pain clinic. While the medication showed no effect, but after the patient received four sessions of bilateral trigger point injections in the temporal muscles her (pain score) score eventually decreased from 10 to 2. The patient is currently continuing medication while still experiencing headaches at reduced intensities.

Treatment Botox Injections

In May 2019, doctors writing in the journal BMJ case reports (3) of a 51-year-old woman with an extensive medical history. “Initially, the patient presented with polypharmacy, having been treated with standard medications such as metoprolol, amlodipine, senna, keppra, topiramate and norco. The patient’s chronic daily headaches proved resistant to these treatments. Nimodipine was given as a vascular smooth muscle stabilizer to treat Reversible Cerebral Vasoconstriction Syndrome as it has been suggested for thunder clap headache treatment.”

The case doctors continued: “Unfortunately, chronic daily headaches remained unaltered and thunder clap headache persisted for a 3-year period. After great consideration, multiple literature reviews and patient consent, OnabotulinumtoxinA (Botox) was successfully used, resulting in remarkably decreased chronic daily headaches and increased quality of life. In addition to subsiding headaches, quality of life improved as patient’s orgasm-triggered thunder clap headache abated post-OnabotulinumtoxinA (Botox).

Alterations in cerebrospinal fluid.

How does venous obstruction occur in a neck?

We are finding in outcome research that a cause of cerebrospinal fluid accumulation and cause pressure inside the head is elevated venous obstruction (vein blockage).
This can be caused by a stretching of the veins. This can be caused by the patient’s head moving forward on their shoulders. When the head is in this position, the veins get pulled on and stretched out. This narrows the veins. A narrowed vein has less room for blood and fluid to flow in, this narrowing caused by cervical spine instability, which leads the head forward is characteristic of the problems faced with stenosis.

Treatment guidelines can be found in our articles:

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