Can cervical spine instability be a cause of Idiopathic Thunderclap Headache

Ross Hauser, MD.

Thunderclap headache is a very specific and potentially life-threatening clinical presentation. If you are reading this article, you or someone you care about has likely experienced one of these sudden, severe headaches and are searching for answers. This discussion begins with an important assumption: that appropriate emergency evaluation has already been completed. In patients experiencing a first-time thunderclap headache, immediate medical assessment is essential to rule out serious conditions such as subarachnoid hemorrhage, intracranial aneurysm rupture, cervical artery dissection, cerebral venous sinus thrombosis, reversible cerebral vasoconstriction syndrome (RCVS), pituitary apoplexy, and other neurological emergencies. Only after these conditions have been excluded should the diagnosis of idiopathic thunderclap headache be considered.

The term idiopathic simply means that no definitive cause has been identified despite an appropriate diagnostic evaluation. However, “idiopathic” does not necessarily mean that an underlying cause does not exist. It may instead reflect limitations in current diagnostic approaches or an underrecognized mechanism that has not yet been fully investigated.

Emerging research, including findings from our own investigations, suggests that some patients diagnosed with idiopathic thunderclap headache may have previously unrecognized abnormalities involving the craniocervical junction. These include craniocervical instability, dynamic internal jugular vein compression, altered cerebrospinal fluid (CSF) dynamics, impaired cerebral venous drainage, and autonomic nervous system dysfunction. These structural and physiological abnormalities may influence intracranial pressure regulation, cerebral blood flow, or pain-sensitive neurological structures, providing a plausible explanation for symptoms in a subset of patients whose standard neurological imaging appears normal.

One proposed mechanism is cervical spine instability. Excessive motion at the upper cervical spine may, in susceptible individuals, contribute to transient vertebral artery compromise during head and neck movement, mechanical irritation of pain-sensitive tissues surrounding the craniocervical junction, abnormal tension on the dura mater and upper cervical ligaments, or disruption of autonomic pathways through irritation of the sympathetic nervous system. In addition, instability may contribute to impaired venous outflow through intermittent compression of the internal jugular veins, potentially altering intracranial pressure dynamics. While these mechanisms remain an area of active investigation and are not yet established causes of idiopathic thunderclap headache, they represent important hypotheses that warrant further clinical and scientific study, particularly in patients who continue to experience recurrent thunderclap headaches despite otherwise unrevealing neurological evaluations.

Symptoms that may point to cervical spine instability as a cause of Idiopathic Thunderclap Headache

Chronic neck pain
Symptoms that worsen with head position such as dizziness, tinnitus, visual disturbances, dysautonomia, or occipital headaches.
Past whiplash or cervical trauma injury
Generalized joint hypermobility or hypermobile Ehlers-Danlos syndrome
Medical diagnosis of upper cervical instability

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 a 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 a thunderclap headache “worst headache of my life.” It went away after two minutes. Three days later, I was riding a 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 have been 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.

In this video Dr. Hauser suggests that some patients with recurrent thunderclap headaches, ocular migraines, hemiplegic migraines, or other episodes of transient neurological dysfunction may have reversible cerebral vasoconstriction or intermittent arterial spasm rather than a primary migraine disorder. He suggests vagus nerve degeneration may contribute to cerebral vasospasm by reducing the vagus nerve’s ability to counteract sympathetic nervous system activity. Based on this, some patients may have cervical instability or cervical structural abnormalities may impair vagus nerve function, leading to excessive sympathetic activation and intermittent vasoconstriction affecting the brain and other organs.

The Idiopathic Thunderclap Headache

Many people will report to us a diagnosis or a description of a “thunderclap headache.” They will tell us how extremely painful these headache episodes were, and how these headaches come about suddenly and without warning (like the loud clap of thunder on a sunny day). Just like thunder, these headaches reach the highest pain intensity within the first minute and can pass very quickly. Again, this type of headache must be explored as a symptom of a more serious neurological or brain issue such as hemorrhage or aneurism. In this section, we will talk about the “benign” thunderclap headache, where the headache seemingly, let’s stress the word seemingly, has no obvious cause.

We are going to briefly cite a paper from Dr. Anish Bahra of The National Hospital for Neurology and Neurosurgery, University College London published in the Journal of Neurology in March 2020 (1) that explains the various pathologies of the thunderclap headache.

“Thunderclap onset headache has also been associated with a multitude of secondary pathologies. A systematic review of (research) identified 119 causes in a total of 2345 cases reported in isolation, case series, or cohorts. . . By far the largest contribution was primary (a separate) headache in 459 cases, 213 primary thunderclap headaches, followed by primary sexual headache in 182, bath-related headache in 37, and exertional headache and combinations of the aforementioned (causes).

Three-hundred and ninety-eight cases were (caused) by cerebrovascular disorders (blood flow in the brain was disrupted by varying causes, this could include stenosis, clot, etc.) 206 from subarachnoid hemorrhage, 46 from other sources of intracranial hemorrhage, venous and arterial thromboembolism, intracranial dissection (rupture in an artery), stroke, hypertensive encephalopathy, and vasculitis.

Included were 18 cases likely to be incidental findings, primarily unruptured cerebral aneurysms.

One hundred and sixty cases of sudden and severe headache were reported in association with infection, 44% affecting the central nervous system and the remainder systemic with likely central nervous system involvement or, encompassed within the terminology of a ‘viral illness’ without further elaboration.

One hundred and seventy-three patients were diagnosed with reversible vasoconstrictive ‘syndrome’ (reversing a narrowing of the artery condition).

The largest contribution to the 119 non-vascular precipitants was from pituitary apoplexy in 43 cases and 32 related to alterations in cerebrospinal fluid. Less than 20 cases were related to the peripartum state and drugs.”

Of interest for our purpose and line of work in the alterations in cerebrospinal fluid.

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

The function of cerebral blood vessels is maintained by signals mainly supplied by sympathetic nerves arising from the superior cervical sympathetic ganglion. The Superior Cervical Ganglion or the superior cervical sympathetic ganglion is part of our flight-fight response and a key component of our messaging network that sends crucial instructions through the body. 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 vessels, 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.

superior cervical sympathetic ganglion

Thunderclap headache, sexual arousal, and neck instability

We often receive emails from people whose long medical history will point to the genesis of their problems. Here is one such email as it relates to sexual function and thunderclap headaches.

This person reported that fifteen years prior they had suffered from bouts of vertigo after an intense massage where the therapist manipulated his neck and head in several inverted positions. Successful treatment for the vertigo was achieved with IV Ativan (for seizures) meclizine (nausea medication) and physical therapy. The person reported over the years, vertigo bouts would come and go, sometimes months, sometimes years apart.

Three years ago this person then reported that they suffered a thunderclap migraine after sexual intercourse. A lumbar puncture was performed to rule out a cerebral hemorrhage. Diagnosis suggested that it was Reversible Cerebral Vasoconstriction Syndrome.

In March 2023, researchers writing in the publication Cephalalgia: An International Journal of Headache (2) wrote: “Primary headache associated with sexual activity is a ‘primary’ headache precipitated by sexual activity, which occurs as sexual excitement increases (progressive at onset), or manifests as an abrupt and intense headache upon orgasm (thunderclap at onset) or combines these above two features.

Primary headache associated with sexual activity is diagnosed after a thorough investigation, including appropriate neuroimaging studies, to exclude life-threatening secondary causes such as subarachnoid hemorrhage. . . .The pathophysiology of primary headache associated with sexual activity and primary thunderclap headache remains incompletely understood. Treatment may not be necessary for all patients since some patients with the primary headache associated with sexual activity and primary thunderclap headache have a self-limiting course.”

A Thunderclap headache after bowel movements non-responsive to medications. Doctors found a cause in the temporal muscles.

Above we discussed thunderclap headache after orgasm or sexual arousal. Next, we will discuss thunderclap headaches after bowel movements and look for connections.

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 (3) 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 the main driver of the headache.

The doctors performed a brain computed tomography (CT) and head and neck magnetic resonance angiography while the patient had a 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 – but 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, 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.

Several treatment types for Thunderclap headache

A list of medications is described above. Here, in the medical publication STAT PEARLS (4) 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 the 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.

Alterations in cerebrospinal fluid.

How does venous obstruction occur in the neck?

We are finding in outcome research that a cause of cerebrospinal fluid accumulation and 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 is caused by cervical spine instability, which leads to the head forward and is characteristic of the problems faced with stenosis.

Reversible Cerebral Vasoconstriction Syndrome and Posterior reversible encephalopathy syndrome

In this section, we will concentrate on one aspect of the cause of symptoms. Cervical spine instability.

Reversible cerebral vasoconstriction syndrome is generally seen as the sudden onset thunderclap headache that with certain treatment programs can be resolved.

In the July 2022 Stat Pearls (5) (Stat Pearls is a publication of the National Center for Biotechnology Information, U.S. National Library of Medicine) update of Reversible Cerebral Vasoconstriction Syndromes, Reversible Cerebral Vasoconstriction Syndromes is described as a “medical condition in which there is multifocal (plural syndromes)arterial constriction (simply a narrowing of the arteries) and dilation in the cerebral vasculature (narrowing or reduction of blood and oxygen to the brain) and which may be associated with nonaneurysmal (leak/ non-rupture) subarachnoid hemorrhage.”

As the diagnosis implies, this is reversible. The authors write there are many causes of Reversible Cerebral Vasoconstriction Syndrome. One cause may be related to the neurology that runs through the cervical spine. They write: “The cerebral vasculature receives heavy innervation from sensory fibers of both the trigeminal nerve and the dorsal root of C2.” This of course is only a possible explanation. The authors also write: “Clinicians should include reversible cerebral vasoconstriction syndrome as a differential in all patients presenting with a thunderclap headache, especially recurrent thunderclap headache.”

Doctors at Emory University School of Medicine published their findings centered around a case history of a common cause of Posterior reversible encephalopathy syndrome and Reversible Cerebral Vasoconstriction Syndrome. The case appears in the Journal of Stroke and Cerebrovascular Diseases. (6)

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.”

In the above papers, we have a discussion of blood vessels, endothelial dysfunction, the breakdown of the blood-brain barrier, and possible neurologic problems in the cervical spine region. Are these issues that may be traced to cervical spine instability?

Marfan Syndrome

A November 2024 case history in the journal Brian sciences (7) discusses patients with Marfan Syndrome and other connective tissue disorders who are at an increased risk for dural ectasia (a widening or thinning of the membrane covering the spinal cord) which may predispose them to spontaneous CSF leaks due to the structural weakness of their dural membranes. The authors continue: “The management of Spontaneous intracranial hypotension in Marfan Syndrome patients is debated. Conservative measures, an epidural blood patch (EBP), and surgical treatments are the options generally provided.” Then they go on to report a case of a a 52-year-old female affected by Marfan Syndrome with a two-month history of sudden-onset, “thunderclap” headache, worsened in an upright position and horizontal diplopia (double vision). A Computed Tomography (CT) scan of the brain showed a bilateral chronic subdural hematoma (old blot clots), slit ventricles, and a caudal descent of the brainstem without overt tonsillar herniation. The Magnetic Resonance Imaging (MRI) scan of the whole spine revealed dural ectasia in the lumbosacral area and presacral perineural cyst without extradural CSF collection. The case was successfully managed with bed rest and high-dose corticosteroid therapy.

Other causes

In December 2024, a paper lead by researchers at the Rennes University Hospital in France (8) describe the first case of Reversible cerebral vasoconstriction syndrome in which methylphenidate, a drug with vasoconstrictive properties, is suspected. Here a 44-year-old French female presented with sudden onset of severe thunderclap headache during exercise. She had been treated for about 2 years with 54 mg extended-release methylphenidate twice a week for attention deficit / hyperactivity disorder. After clinical, biological and imaging examinations, clinicians concluded to a highly probable Reversible cerebral vasoconstriction syndrome diagnosis, probably linked to methylphenidate use.

A November 2024 case report in the journal Clinical case reports (9) describes a 41-year-old woman with chronic anemia, acute chronic kidney disease, type 2 diabetes mellitus, and rheumatoid arthritis who developed Reversible cerebral vasoconstriction syndrome following transfusion of packed red blood cells. She experienced sudden-onset seizures and a thunderclap headache 5 days post-transfusion.

Summary and contact us. Can we help you? How do I know if I’m a good

Our published research

The Biology of Prolotherapy and Its Application in Clinical Cervical Spine Instability and Chronic Neck Pain

Cervicovagopathy: ligamentous cervical instability and dysstructure as a potential etiology for vagus nerve dysfunction in the cause of human symptoms and diseases

The ligamentous cervical instability etiology of human disease from the forward head-facedown lifestyle

References

1 Bahra A. Other primary headaches—thunderclap-, cough-, exertional-, and sexual headache. Journal of neurology. 2020 May;267(5):1554-66. [Google Scholar]
2 Lin PT, Chen SP, Wang SJ. Update on primary headache associated with sexual activity and primary thunderclap headache. Cephalalgia. 2023 Mar;43(3):03331024221148657. [Google Scholar]
3 Ji JY, Jung HS, Yoo SH, Son HD, Kim AJ. Reversible cerebral vasoconstriction with thunderclap headache: A case report. Medicine. 2019 Dec;98(49). [Google Scholar]
4 Sekhon S, Sharma R, Cascella M. Thunderclap Headache. InStatPearls [Internet] 2021 Jul 25. StatPearls Publishing. [Google Scholar]
5 Nesheiwat O, Al-Khoury L. Reversible cerebral vasoconstriction syndromes. InStatPearls [Internet] 2022 Jul 4. StatPearls Publishing. [Google Scholar]
6 Jeanneret V, Jillella DV, Rangaraju S, Groover O, Peterson R, Koneru S, Nahab F, Kase CS. PRES and RCVS: Two Distinct Entities or a Spectrum of the Same Disease?. Journal of Stroke and Cerebrovascular Diseases. 2022 Jun 1;31(6):106472. [Google Scholar]
7 Signorelli F, Ktari O, Agostini L, Ducoli G, Zeoli F, Visocchi M. Spontaneous Intracranial Hypotension and Dural Ectasia in Marfan Syndrome: An Illustrative Case Successfully Treated with Steroid Therapy and Literature Review. Brain Sciences. 2024 Nov 15;14(11):1143.
8 Osmont MN, Malrain C, Ruellan AL, Benchikh A, Herlem E, Polard E, Scailteux LM. Reversible cerebral vasoconstriction syndrome in a methylphenidate-treated patient: a case report. BMC neurology. 2024 Dec 31;24(1):494. [Google Scholar]
9 Verma A, Sharma G, Singh A, Gupta H, Singh DP, Gaidhane AM, Khatib MN, Bushi G, Sah S, Ndabashinze R. Reversible Cerebral Vasoconstriction Syndrome Following Blood Transfusion in a Patient With Chronic Anemia: A Case Report. Clinical Case Reports. 2024 Dec;12(12):e9618. [Google Scholar]