Cervical spine instability

Instability can significantly impact a patient’s life. Yet, the diagnosis of cervical spine instability, the ability to get to the root cause of the patient’s problems is still perplexing to many health care providers, and misdiagnosed or missed by over 90% of Doctors and facilities. We see many people who have had many MRIs, CT scans, and x-rays, and hearing a different clinician give another explanation for their symptoms. Then with no immediate answers, the patient is thrust into a myriad of medications, treatments, and surgeries without relief. Eventually, the patient goes to pain management and is placed on long-term narcotics. Often the families and even spouses do not understand because the person “looks normal.” Brain Physiology is how the brain works. In this review article, a brief description is offered of how cervical spine instability can impact brain physiology.

Cervical Spine Instability Potential Effects on Brain Physiology

All vascular and nerve tracks that travel to and from the brain go through the neck; as such cervical structural changes including instability can potentially affect brain physiology and give symptoms. Cervical instability is known to cause many symptoms including headaches, vision changes, brain fog, dizziness, weakness, drop attacks, and imbalance. The cause of neurological issues that arise in cervical instability is unclear. One cause could be cervical instability affecting brain physiology.

The flow of nerve impulses are disrupted primarily by one of four mechanisms:

(1) direct compression or irritation by a structure such as a vertebral bone or muscle spasm,

(2) interruption in its own nutrition through disruption of arterial blood flow,

(3) blockage of cerebrospinal fluid flow, or

(4) hindrance of venous drainage, which is also associated with number 3. important in understanding how instability, especially in the neck, can disrupt nervous system transmission of impulses.

Common symptoms from just ONE of the physiological damages due to instability:

1. Chronic fatigue
2. Vision problems
3. Loss of vision in one eye
4. Nystagmus – Oscillopsia
5. Blurred or Double Vision Problems
6. Swallowing difficulties
7. Temperature dysregulation
8. Dysesthesias or “abnormal sensations”
9. Tactile hallucinations and Formication: Strange skin sensations
10. Brachioradial Pruritis – Neuropathic itch
11. Bowel – digestive disorders
12. Bladder problems
13. Cognitive difficulties, depression, and anxiety
14. Amnesia

More detail on these below!!

Common symptoms, a common confusion

We are often contacted by people who had symptoms of Multiple Sclerosis but a brain MRI ruled MS out. This however left the patient and their neurologist at a loss as to what may be causing the person’s MS-like symptoms and conditions. Craniocervical Instability, upper cervical spine instability, cervical spine instability, and Multiple Sclerosis share the following challenges. This of course is a general guide, in both Multiple Sclerosis and cervical spine instability, the symptoms and conditions can vary greatly and appear more or less severe in people.

Fatigue

Chronic fatigue. Many people who reach out to us have a diagnosis of Myalgic encephalomyelitis (muscle pain from nerve inflammation) or Chronic Fatigue Syndrome. Fatigue in these people is part of a complex medical history. Sometimes this is diagnosed as Fibromyalgia.

Vision problems

If you have been suffering from vision problems related to neck instability, you know that these problems can come with different impairments. MS patients and cervical neck instability patients can share problems of:

Loss of vision in one eye. Symptoms of Transient monocular blindness – Amaurosis fugax – Transient visual loss. You suffer from a temporary loss, or a slow fading out to gray, in the vision of one of your eyes.

Nystagmus – Oscillopsia type symptoms where you have a vision problem where you see things that bounce, jump or appear to be in some type of motion when in fact these objects are not moving at all.

Blurred or Double Vision Problems

Swallowing difficulties

Cervical spine nerve compression can be an “unseen” cause of swallowing difficulties.

Temperature dysregulation

As noted in a detailed paper in the Journal of applied physiology (x), people with a diagnosis of MS may suffer from problems of heat sensitivity, central regulation of body temperature; and thermoregulatory effector responses (the ability to maintain a core body temperature). These are the same challenges people not diagnosed with MS but have cervical instability suffer from as well. Please see my articles:

Thermoregulatory instability – Neck pain and inability to maintain consistent body temperature

Excessive Sweating – Hyperhidrosis. Is upper cervical instability the missing treatment?

Dysesthesias or “abnormal sensations”

Some MS patients share a common characteristic with cervical spine instability patients in that they sense “weird” or “strange” sensations beyond numbness and tingling or electric shock sensation in their skin.

Some of the common characteristics a cervical spine instability patient may experience:

Tactile hallucinations and Formication: Strange skin sensations

Brachioradial Pruritis – Neuropathic itch

Bowel – digestive disorders

Some of the common characteristics of a cervical spine instability patient may experience conditions related to poor digestion. Please see my articles:

How neck pain and cervical spine instability cause nausea, gastroparesis, and other digestive problems

Cervical spine instability as a cause of your digestive disorders

Bladder problems

Some of the common characteristics of a cervical spine instability patient may experience conditions related to urinary problems including the need to urinate more frequently and urgently which may ultimately lead to a loss of bladder control and urge incontinence problems.

Neurologic, digestive, cardiac, and bladder disorders: Some of the symptoms of Autonomic nervous system dysfunction and treatment options.

Cervical spine problems, Vagus nerve compression, as cause urinary incontinence

Cognitive difficulties, depression, and anxiety

These conditions and problems are of course and unfortunately very common in all people who suffer from chronic medical conditions. We will discuss these challenges later in this article.

Amnesia

In July 2015, doctors reported in the medical journal PloS One (15) of a link between obstruction of venous drainage and transient global amnesia. Transient global amnesia being a sudden, temporary memory loss without stroke or epileptic seizure. Simply, the patients ability to recall recent events disappears. They can not remember where there are or the sequence of events that got them there. Here is what the researchers observed and recorded:

Abnormal extracranial venous drainage modality has been considered an etiology of transient global amnesia. The researchers suggested that obstruction of internal jugular venous drainage is a contributing factor in transient global amnesia pathogenesis. What they found was when patients with transient global amnesia were compared to patients without transient global amnesia, transient global amnesia patients had significantly higher rates of moderate and severe compression/stenosis at the bilateral upper-IJV segment in left brachiocephalic vein and in transverse sinus hypoplasia (less cells). The prevalence of at least one site of venous compression/stenosis in IJV or brachiocephalic vein was significantly higher in patients than in controls.

In February 2019, the same researchers added to these findings. Publishing in the journal Frontiers in neurology (16) doctors wrote: “Previous neuroimaging and ultrasound studies suggested that compression and stenosis of the internal jugular vein in patients with transient global amnesia may impair internal jugular vein drainage, while a patent IJV releases intracranial pressure caused by the Valsalva maneuver (forcing exhales against obstructed or blocked structures). The researchers noted that they could confirm that the total venous flow decreases in the IJVs and vertebral vein of the patients with transient global amnesia. This is consistent with the findings of previous MR imaging studies that have reported about compression and stenosis of the draining veins.

Chronic Cerebrospinal Venous Insufficiency: Breaking away from a Multiple Sclerosis only type condition

Please see my companion article Chronic Cerebrospinal Venous Insufficiency and neurologic-like problems.

Chronic Cerebrospinal Venous Insufficiency is exactly what it sounds like. You have a chronic problem moving cerebrospinal fluid out of the brain via the venous or vein network.

A 2019 study in the journal Reviews on Recent Clinical Trials (3) examined the Chronic Cerebrospinal Venous Insufficiency and its relationship with Multiple Sclerosis and found that this condition could be prevalent in other disorders. Here is what the researchers wrote:

“About 10 years ago, the so-called chronic cerebrospinal venous insufficiency syndrome was discovered. This clinical entity, which is associated with extracranial venous abnormalities that impair venous outflow from the brain, was initially found exclusively in multiple sclerosis patients. Currently, we know that such venous lesions can also be revealed in other neurological pathologies, including Alzheimer’s and Parkinson’s diseases. Although the direct causative role of chronic cerebrospinal venous insufficiency in these neurological diseases still remains elusive, in this paper, we suggest that perhaps abnormal venous drainage of the brain affects the functioning of the glymphatic system (the waste clearance system of the central nervous system) which in turn results in the accumulation of pathological proteins in the cerebral tissue (such as β-synuclein, β-amyloid, and α-synuclein) and triggers the venous outflow from the cranial cavity and circulation of the cerebrospinal fluid in the settings of neurodegenerative disease.”

In this paper, there is an identification with the brain being unable to drain wastes and that these accumulated wastes would lead to degenerative disorders. We find here similarities in our cervical spine instability patients. We will discuss this important concept shortly.

The idea that upper cervical spine instability impacts heart rate variability and this may be a culprit of your symptoms, is not a new idea.

The idea that upper cervical spine instability impacts heart rate variability and this may be a culprit of your symptoms, is not a new idea. In our 28 years of helping patients with problems related to the cervical spine, we have seen these symptoms many times. Yet medical research is not yet that abundant. In our own peer-reviewed published studies we have been able to document cervical neck ligament damage as a possible cause of low HRV as to when cervical neck ligaments are damaged or weakened by wear and tear damage or injury, they allow the upper cervical instability that can impinge on the cervical nerves. We will be citing this research below. First, we will explore some independent research.

The first two studies, the first being from neurosurgeons, the second from chiropractors, both discuss the benefit of treatment, surgery, or chiropractic care.

In April 2011, in the medical journal Spine, (7) Doctors at the Department of Neurosurgery, National Institute of Mental Health and Neuro Sciences in India examined patients with the suspected autonomic nervous system (ANS) and cervical compressive myelopathy. The researchers noted, “there are no studies on compressive myelopathies.”

So what does nerve compression do?

The researchers evaluated 29 adult patients with cervical compressive myelopathy. Conventional autonomic function tests and Heart Rate Variability HRV were studied in these patients.

The same tests were done on 29 age- and sex-matched healthy controls. Study learning points:

Patients with cervical compressive myelopathy as compared with controls showed a significant difference in the following parameters;

Deep breathing, Valsalva ratio

Explanation note: Valsalva Ratio is the outcome of the Valsalva Maneuver. In the Valsalva Maneuver, similar to trying to get water out of your ears, you exhale forcefully with a closed mouth and pinched nose to create “internal pressure.” It is a test that can help determine the cardiac function and autonomic nervous control of the heart. Among other things, it measures the “R-R interval” the specific changes in time (or variability) between successive heartbeats.

The researchers found: “Patients with cervical compressive myelopathy have definite Autonomic nervous system dysfunction as compared to healthy age- and sex-matched controls. There is a significant improvement in the Valsalva ratio after (decompression) surgery.”

For some people, surgery can be an answer. This is not our answer. We will discuss our non-surgical treatments below.

It is not my neck, my doctor says there is no connection between my neck problems and my cardiovascular problems

Above we discussed that when we see new patients they come to us with not one or two or a few symptoms, they can come to us with many symptoms. They also see specialists for every individualized symptom and each specialist treats their specialty symptom. If the cardiologist cannot control rapid heartbeat with heart medicines, the person may be sent to a mental health specialist for specialized psychiatric medications. If the person with cardiovascular-type symptoms is having hearing problems, they see an ear specialist, digestive problems, a GI specialist, etc. For some people, this separation of specialties may help them considerably. For others, they enter the rabbit hole of years and years of testing, hit-and-miss medication prescriptions, and a typical sense of nothing helps.

At our center, we try to focus on people who have all these symptoms as a person who may have a general underlying cause to their problems. That is a problem of cervical spine instability as discussed throughout this article.

Sometimes a person will contact us with cardiovascular-like problems with no apparent cause. They have arrhythmias, the tachycardia, blood pressure swings, a sensation of burning mouth, TMJ, and spasms, ticks, dizziness, and vision problems. They also have neck pain. Some have cervical stenosis, some have bone spurs, some have difficulty holding their head up. When they search the internet for any information that makes sense to them sometimes they come upon the idea that these neck problems may have something to do with these cardiovascular-like problems. In this article, independent research published in medical journals is discussed to show that other medical professionals have made this connection as well. This is not to say that every person with these symptoms has cervical neck instability or treating cervical neck instability will help every person. Based on our clinical observations and that of other doctors and health care professionals treating cervical neck instability may help many people with these problems.

Occasionally people will tell us that, despite having MRI documented cervical degenerative disease, and that when they turn their heads one way or the other they develop symptoms, their cardiologist tells them that their neck has nothing to do with their heart problems. This may be true for many people, but for someone living with these problems for years and no real resolution of their issues, it can be challenging to believe that their neck has nothing to do with it or that one problem is not connected to the other.

Ross Hauser, MD highlights some of the most common reasons why cervical instability or cervical dysstructure (broken neck syndrome) can be the underlying structural cause of low vagal tone and associated poor heart function, leading to POTS, or dysautonomia.

POTS symptoms may range from mild and occasional complaints to severely incapacitating disease. Sufferers are commonly misdiagnosed as having chronic anxiety or panic disorder or chronic fatigue syndrome.

There is a multitude of other symptoms that often accompany this syndrome including pre-syncope, syncope, dizziness, palpitations, headache, fatigue, bladder, and gastrointestinal (GI) symptoms.

• When the vagus nerve works correctly and you have the proper vagal tone you also have well-regulated blood pressure and heart rate
• When the vagus nerve works correctly and you have a good vagal tone, the vagus nerves can protect your heart via the following:
• The vagus nerves stop the sympathetic nervous system from “over racing” of the heart.
• The parasympathetic nervous system (PNS) releases the hormone acetylcholine to slow the heart rate.

The sympathetic nervous system (SNS) releases hormones from the adrenal glands (catecholamines in the form of epinephrine (formally called adrenaline) and norepinephrine) to accelerate the heart rate. This occurs during times of stress, exercise, physical exertion, etc. When the exercise, stress, or physical exertion is over, the parasympathetic nervous system releases the hormone acetylcholine to slow the heart rate.

The vagus nerves are a major part of the parasympathetic nervous system, the slowing down process.

If these hormone levels are left unchecked or unregulated by the vagus nerves’ involvement in the parasympathetic nervous system, the heart can beat like a runaway train with nothing to stop it except in most cases medications.

Many people report a history of arrhythmias, atrial fibrillation, atrial tachycardia, paroxysmal atrial tachycardia, and ventricular arrhythmias. Some will report atrial ectopic heartbeat. An extra heartbeat comes from the ventricles and disrupts the normal beat pace. This can be the result of the vagus nerves’ inability to slow down the heart rate.

The vagus nerves have the ability to decrease heart inflammatory markers and reduce cardiac inflammation

If your body can’t relax because you have a low vagal tone and the vagus nerves cannot calm down the sympathetic nervous system, systemic inflammation can occur. You can develop chronic inflammation. When the vagal tone is high, the vagus nerve can act as an anti-inflammatory agent, decreasing heart inflammatory markers and thereby reducing cardiac inflammation.

When the vagus nerve is functions as it should, it decreases inflammation in the heart.

The cholinergic anti-inflammatory pathway – “when vagus nerve activity is deficient, inflammation is excessive.”

We are going to look now at a study published in the Journal of Internal Medicine. (8) Here the relationship between cholinergic (as we discussed above is related to messages and signaling) anti-inflammatory pathway and regulation of heart rate variability is noted as an area of intensive study. The researchers of this paper also noted: “the available clinical evidence indicates that when vagus nerve activity is deficient, inflammation is excessive.” They also note: “There are theoretical and practical advantages to developing devices (or treatments) that can selectively activate the cholinergic anti-inflammatory pathway without stimulating cardiac fibers.” Further, they note: “heart rate variability monitors may one day provide indices of diminished or enhanced vagus anti-inflammatory activity.”

Measurements in Heart Rate Variability as a means to show a treatment is working

Chiropractors in Sweden and Denmark are collaborating on a study (9) in which they can use Heart Rate Variability as a measure to detect if spinal manipulation, by reducing a patient’s pain, is impacting itself on the Autonomic nervous system.
The posterior cervical sympathetic nervous system signals the sympathetic part of the autonomic nervous system that controls the head, neck, and face area. In cervical spine neck instability or cervicocranial syndrome, the posterior cervical sympathetic system is underactive because the vertebrae in the neck are pinching the sympathetic nerves.

Let’s let the researchers explain:

“The pain-reducing effects of (spinal manipulation therapy) on certain spinal pain conditions are well established, as are the normal reactions to such treatment. However, the mechanisms behind these effects are not well understood, although it is hypothesized that the pain-reducing effects could be mediated through the Autonomic nervous system”

In other words, spinal manipulation helps people by alleviating pain. But how does the manipulation do it? That is “not well understood.” So what the researchers hypothesized is that it must have something to do with the function of the Autonomic nervous system and that they may be able to show this by measuring Heart Rate Variability.

“Therefore, the study of Heart Rate Variability Responses to Spinal Manipulation Therapy as part of a short treatment plan and its relation to pain sensitivity and normal reactions to treatment will advance knowledge regarding the mechanisms involved in the specific effects of Spinal Manipulation Therapy.”

So here there is speculation that short-term pain relief achieved with chiropractic care can be shown by restoring normal heart rate variability.

Fixing the vagus connection, vagal tone, vagus nerve stimulation, and stabilizing

Much has been said about fixing, repairing, or increasing vagal tone with various vagus nerve stimulation techniques. Vagus nerve electrical stimulation may be one aspect of how we support the repair and reversing of cardiovascular-like symptoms. It is however typically not the primary treatment strategy we employ. Our treatment goal is to remove the compression on the nerves, arteries, and veins that travel through the cervical spine from the brain to the body and back again. We achieve these results by stimulating the repair of the cervical spine ligaments. The connected tissue prevents the bones of the cervical spine from wandering out of place and impinging, squeezing, and compressing the nerves and blood vessels. While electrical stimulation can help repair vagal tone, cervical spine curve correction and cervical spine stability will prevent nerve compression.

The malrotation of the C2 vertebrae or the axis, is often what I call the the Missing Link into what is causing a person’s symptoms.

• Rotated C2 can compress the vagus nerve that can cause digestive problems seen in some upper cervical instability patients.
• Rotated C2 can cause compression on the glossopharyngeal nerve which can cause dysfunction of the larynx muscles and cause swallowing difficulties.
• Rotated C2 can cause compression of the spinal accessory nerve cause cramping into the sternocleidomastoid muscle or the trapezius muscle and creating a situation of torticollis.
• Rotated C2 can cause compression and obstruct right jugular vein causing increased brain pressure and problems of cognitive decline and mood disorders.
• Rotated C2 can compress the carotid sheath causing compression on jugular veins and carotid arteries causing intracranial hypertension.

For more information, please check out Dr. hauser, MD’s website. He is a long standing expert in instabilities of the spine, and has been practicing for decades. We utilize advanced structural spinal correction technqiues in our facility and work alongside with MD, DO that perform prolotherapy on a consistent basis to deliver our patients the best results we can.

References

1. B. Bragée, et al. Signs of Intracranial Hypertension, Hypermobility, and Craniocervical Obstructions in Patients With Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Front

Neurol 11 (2020): 828 [Google Scholar]

2 Degnan AJ, Levy LM. Pseudotumor cerebri: brief review of clinical syndrome and imaging findings. American journal of neuroradiology. 2011 Dec 1;32(11):1986-93. [Google Scholar]

3. J. N. Higgins, et al. An Evaluation of Styloidectomy as an Adjunct or Alternative to Jugular Stenting in Idiopathic Intracranial Hypertension and Disturbances of Cranial Venous Outflow. J

Neurol Surg 78.2 (2017): 158–163 [Google Scholar]

4. D. S. Ruíz, et al. The Craniocervical Venous System in Relation to Cerebral Venous Drainage. Amer J Neurorad 23.9 (2002): 1500-1508

5 Farb RI, Vanek I, Scott JN, Mikulis DJ, Willinsky RA, Tomlinson G. Idiopathic intracranial hypertension: the prevalence and morphology of sinovenous stenosis. Neurology. 2003 May 13;60(9):1418-24. [Google Scholar]

6 Thompson DN, Harkness W, Jones B, Gonsalez S, Andar U, Hayward R. Subdural intracranial pressure monitoring in craniosynostosis: its role in surgical management. Child’s Nervous System. 1995 May;11(5):269-75. [Google Scholar]

7 Lima AC, Bittar R, Gattas GS, Bor-Seng-Shu E, Oliveira MD, Monsanto RD, Bittar LF. Pathophysiology and diagnosis of vertebrobasilar insufficiency: a review of the literature. International archives of otorhinolaryngology. 2017 Jul;21:302-7. [Google Scholar]

8. M. D. Schauber, et al. Cranial/cervical nerve dysfunction after carotid endarterectomy. J Vasc Surg 25.3 (1997): 481-487 [Google Scholar]

9. Darren H. Garner, et al. Anatomy, Head and Neck, Carotid Sheath. “StatPearls.” 1 st ed. StatPearls Publishing. Treasure Island, FL, US. (2020). [Google Scholar]

10 Geraud G. Vasodilatation et migraine. Revue Neurologique. 2014 Apr 1;170:A218-9 [Google Scholar]

11 Moubayed SP, Saliba I. Vertebrobasilar insufficiency presenting as isolated positional vertigo or dizziness: A double‐blind retrospective cohort study. The Laryngoscope. 2009 Oct;119(10):2071-6. [Google Scholar]

12 Yolas C, Kanat A, Aydin MD, Altas E, Kanat IF, Kazdal H, Duman A, Gundogdu B, Gursan N. Unraveling of the effect of nodose ganglion degeneration on the coronary artery vasospasm after subarachnoid hemorrhage: an experimental study. World neurosurgery. 2016 Feb 1;86:79-87. [Google Scholar]

13. P. K. Eide, et al. Magnetic resonance imaging provides evidence of glymphatic drainage from human brain to cervical lymph nodes. Sci Reports 8.7194 (2018): 1-10

14 Mattle HP, Arnold M, Lindsberg PJ, Schonewille WJ, Schroth G. Basilar artery occlusion. The Lancet Neurology. 2011 Nov 1;10(11):1002-14. [Google Scholar]

15 Kuether TA, Nesbit GM, Clark WM, Barnwell SL. Rotational vertebral artery occlusion: a mechanism of vertebrobasilar insufficiency. Neurosurgery. 1997 Aug 1;41(2):427-33. [Google Scholar]

16 Hartmann CJ, Klistorner AI, Brandt AU, Schroeder K, Kolbe R, Cohn E, Goebels N, Guthoff R, Aktas O, Hartung HP, Albrecht P. Axonal damage in papilledema linked to idiopathic intracranial hypertension as revealed by multifocal visual evoked potentials. Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology. 2015 Oct;126(10):2040-1. [Google Scholar]

17. A. R. Nippert, et al. Mechanisms mediating functional hyperemia in the brain. The Neuroscient 24.1 (2018): 73-83

18 Dabus G, Gerstle RJ, Parsons M, Cross III DT, Moran CJ, Thompson R, Derdeyn CP. Rotational vertebrobasilar insufficiency due to dynamic compression of the dominant vertebral artery by the thyroid cartilage and occlusion of the contralateral vertebral artery at C1–2 level. Journal of Neuroimaging. 2008 Apr;18(2):184-7. [Google Scholar]

19 Honey CR, Krüger MT, Morrison MD, Dhaliwal BS, Hu A. Vagus Associated Neurogenic Cough Occurring Due to Unilateral Vascular Encroachment of Its Root: A Case Report and Proof of Concept of VANCOUVER Syndrome. Annals of Otology, Rhinology & Laryngology. 2020 May;129(5):523-7. [Google Scholar]

20. Weissman‐Fogel I, Dashkovsky A, Rogowski Z, Yarnitsky D. An animal model of chemotherapy‐induced vagal neuropathy. Muscle & Nerve: Official Journal of the American Association of Electrodiagnostic Medicine. 2008 Dec;38(6):1634-7. [Google Scholar]

21 Goel A, Ranjan S, Shah A, Rai S, Dandpat S, Patil A, Vutha R. Adjacent-segment “central” atlantoaxial instability and C2–C3 instability following lower cervical C3–C6 interbody fusion: Report of three cases. Journal of craniovertebral junction & spine. 2020 Jan;11(1):51. [Google Scholar]

22 Goswami A. Prolotherapy. Journal of pain & palliative care pharmacotherapy. 2012 Dec 5;26(4):376-8. [Google Scholar]

23 Dagenais S, Yelland MJ, Del Mar C, Schoene ML. Prolotherapy injections for chronic low‐back pain. Cochrane Database of Systematic Reviews. 2007(2). [Google Scholar]

24. Carcamo CR. Pulsed radiofrequency of superior cervical sympathetic ganglion for treatment of refractory migraine. Pain Medicine. 2017 Aug 1;18(8):1598-600. [Google Scholar]

25. G. Attanasio. Chronic cerebrospinal venous insufficiency and menière’s disease: Interventional versus medical therapy. Laryngoscope 130.8 (2020): 2040-2046

26 Takeshima Y, Nakase H. Variations in Cervical Degenerative Diseases: What are the Key-points in Diagnosis?. No Shinkei geka. Neurological Surgery. 2021 Nov 1;49(6):1171-82. [Google Scholar]