Head Pressure, Migraine and the Failure of Adaptive Reserve
Updated: 3 days ago
Dr Graham Exelby September 2026- A Series of 5 Papers
Executive Statement
Head pressure, migraine, pulsatile tinnitus, visual disturbance, cognitive dysfunction and dysautonomia are usually approached as separate diagnostic problems. This series examines a different possibility: that in a substantial subset of patients with POTS, Long COVID and related disorders, these symptoms may represent different expressions of failure within an interconnected physiological system responsible for cerebral perfusion, cranial venous drainage, cerebrospinal-fluid distribution, interstitial and lymphatic clearance, systemic preload, microvascular homeostasis and neurovascular adaptation.
The four principal papers bring together concepts developed through longitudinal investigation and clinical observation in an extended cohort of more than 700 patients with POTS and related disorders, in whom head pressure has emerged as a prominent and often poorly explained symptom.
They are accompanied by a focused companion paper, Why Stylojugular Decompression May Not Be Enough, which applies the same network principles to the practical problem of intervention and incomplete physiological recovery after focal jugular decompression. The models have evolved progressively as recurring clinical patterns have been compared with detailed anatomy, dynamic vascular imaging, cerebral imaging, physiological testing and responses to treatment. They are not presented as evidence that one mechanism explains POTS, Long COVID, migraine or head pressure. They are presented as a developing physiological framework through which apparently separate abnormalities may be examined as components of an adaptive system.
The central concept is adaptive reserve. Anatomical abnormalities are common and do not necessarily cause symptoms. A substantial narrowing may remain well tolerated when collateral pathways, tissue compliance, systemic haemodynamics and downstream drainage remain effective.
Several individually modest abnormalities may interact when they occur within the same low-pressure system, progressively consuming the capacity to compensate. Symptoms may therefore emerge not simply because an anatomical lesion exists, but because posture, cervical mechanics, respiration, systemic preload, inflammation, tissue hypoxia or another physiological demand pushes an already constrained system beyond its remaining reserve.
This distinction changes the clinical question. The objective is no longer simply to identify what looks abnormal. It is to determine where physiological reserve is being lost, which responses are maintaining compensation, what process is continuing to impose the load, and which component can be modified without destabilising the adaptations that remain.
How the Series Developed
The series began with observations that did not fit comfortably within conventional diagnostic categories. Symptoms could change dramatically with posture or mechanical loading. Anatomically impressive abnormalities were sometimes relatively silent, while apparently modest abnormalities could be associated with profound physiological disturbance. A treatment that produced striking improvement in one patient could worsen another with superficially similar symptoms.
These contradictions led repeatedly back to anatomy, but with a different purpose. The question became not merely what structure is abnormal? but how does alteration of that structure change the physiology of the complete system, and what function is an apparently abnormal structure currently serving?
The methodology that evolved has been:
clinical observation → anatomical localisation → physiological hypothesis → dynamic investigation → identification of driver and compensation → follow recruited pathways to their downstream destination → cautious intervention → reassessment of the redistributed system
This has repeatedly demonstrated the importance of distinguishing pathology from adaptation. A collateral vein may be preserving cranial drainage. A dilated vessel may indicate upstream resistance rather than primary disease. Increased suboccipital tone may be stabilising a mechanically vulnerable cranio-cervical junction. Tachycardia may be compensating for reduced stroke volume. Tissue fullness may identify an abnormal clearance environment without identifying the direction or exact mechanism of failure.
The series therefore progressively moves beyond static anatomy towards network physiology.
Paper 1 — From a Jugular Lesion to a Cranial–Cervical–Thoracic Network
The Jugular Foramen–Cavernous Sinus Axis begins with the detailed anatomy of the jugular foramen but moves beyond the concept of a focal jugular stenosis.
The jugular foramen lies within a continuous cranial-to-thoracic venous system. The sigmoid sinus–jugular bulb–IJV pathway is connected through the inferior petrosal sinus to the cavernous sinus and, through the cavernous system, to the ophthalmic veins, basilar plexus, emissary veins and pterygoid plexus. Extracranially, the IJV continues through the mobile cervical region, terminal valve, thoracic inlet and venous angle. Resistance at one level therefore cannot be interpreted independently of resistance and compensatory capacity elsewhere.
This paper extends the conventional boundary in three important directions.
First, it shifts attention from percentage stenosis to the physiology of a network. Collateral recruitment may preserve bulk flow while changing regional pressures and consuming adaptive reserve.
A collateral pathway must therefore be followed beyond the point at which it is first recognised. The cavernous–pterygoid route illustrates the principle particularly clearly: cavernous redistribution through skull-base emissary pathways may reach the pterygoid plexus, but the physiological value of that route depends upon its downstream maxillary–retromandibular–facial drainage and whether it ultimately reaches an adequately functioning IJV or an effective EJV–subclavian receiving pathway. Collateral presence is evidence of adaptation; it is not, by itself, evidence of effective bypass.
Second, it extends jugular physiology anteriorly through the cavernous–petrosal–pterygoid and ophthalmic systems, providing a mechanism through which extracranial resistance might potentially be expressed as regional orbital, facial or parasellar venous loading.
Third, it extends the problem beyond the vascular lumen. The jugular-bulb dura and connective-tissue sheath of the initial IJV form a potential dural–venous interface, and contrast-enhanced black-blood MRI opens the possibility of examining surrounding dural and perivascular tissue abnormalities that conventional venography cannot show.
This remains an active area of investigation rather than an established pathological entity.
The therapeutic implication is equally important. Styloid–C1 decompression may be highly effective when that site is genuinely dominant, but correction of one resistance does not automatically normalise the entire pathway. Persistent cervical IJV restriction, terminal valve dysfunction, thoracic-outlet or venous-angle resistance, established collateral dependence or surrounding tissue changes may remain.
Thus the first paper moves the model from focal anatomy to distributed venous physiology.
Paper 2 — From Static Anatomy to Posture as a Physiological Stress Test
Upright and Supine Head Pressure then adds the variable that static imaging largely removes: posture.
The internal jugular system is dominant during recumbency, whereas standing shifts cerebral venous drainage towards vertebral, condylar and other posterior cranio-cervical pathways. At the same time, standing reduces systemic preload and increases the haemodynamic work required to preserve cerebral perfusion. The physiological configuration of the patient is therefore fundamentally different upright and supine.
This produces a clinically useful symmetry:
upright head pressure interrogates posterior cranio-cervical, vertebral–condylar and systemic preload reserve
whereas supine or morning head pressure interrogates jugular-dependent drainage, downstream venous receiving conditions and overnight recovery reserve.
Neither upright pressure automatically means spontaneous intracranial hypotension nor supine pressure automatically means intracranial hypertension. Posture identifies the system being stressed; it does not itself establish a conventional pressure diagnosis.
This paper also extends the model beyond venous drainage alone. CSF movement, meningeal and cervical lymphatic pathways, Pessa's proposed canalicular anatomy, the myodural bridge complex, muscular stabilisation and cranio-cervical mechanics all occupy the same small transition zone but remain anatomically distinct systems whose contributions must be tested rather than assumed.
The paper also revisits the interpretation of apparent CSF leakage. Clear nasal or posterior-pharyngeal fluid requires conventional investigation for a cranial CSF fistula where clinically appropriate. However, experimental identification of nasal and nasopharyngeal CSF-associated lymphatic outflow introduces a second, still unproven possibility in patients whose fluid remains uncharacterised.
The direction of the accompanying head-pressure response becomes an additional physiological observation: progressive orthostatic low-CSF-volume symptoms support pathological CSF loss, whereas repeated relief of a pre-existing pressure phenotype without evidence of progressive depletion may justify investigation of broader cranial clearance physiology. Fluid composition remains an empirical question; symptom response does not identify the fluid.
Dynamic sonography becomes particularly important because the normal physiological expectation is recruitment of vertebral drainage upright. Reduced, absent, intermittent or retrograde vertebral venous flow during the state that produces symptoms therefore becomes a physiological observation rather than simply an anatomical finding.
The paper also extends the model downwards. The head cannot be considered independently of systemic venous return. Cranial drainage, thoracic outlet mechanics, abdominal and pelvic venous capacitance, cardiac preload and autonomic compensation together determine how much reserve remains available when posture changes.
Thus the second paper moves from network anatomy to dynamic whole-body physiology.
It also provides the natural home within the series for the broader posterior collateral anatomy. Mastoid, posterior condylar, suboccipital, vertebral, diploic and other emissary pathways are considered primarily as components of posture-dependent adaptation. Their recruitment may preserve flow as jugular contribution falls, but their presence does not establish that normal pressure gradients or clearance reserve have been restored.
Paper 3 — From the Vessel to the Tissue: ECM, Pericytes and Clearance
When Flow Persists but Clearance Fails crosses another boundary. It asks what happens when measurable blood or lymph flow persists, yet the tissue is no longer being cleared effectively.
The lymphatic system begins functionally within the interstitial compartment rather than at the first visible collecting vessel. Water, proteins, inflammatory mediators and metabolites must move through the extracellular matrix before reaching initial lymphatics. Effective clearance therefore depends on microvascular filtration, ECM hydraulic properties, interstitial diffusion, initial lymphatic uptake, collecting-vessel transport and a favourable pressure gradient at terminal lymphovenous emptying.
A patent major vessel cannot establish that this complete process is functioning normally.
This creates an important convergence without implying anatomical unity: venous and lymphatic pathways remain distinct systems, but terminal lymphatic emptying ultimately encounters a venous receiving environment, so downstream venous pressure may influence the gradient available for lymph return.
This introduces the microvascular–interstitial–lymphatic unit into the series.
Regional hypoxia may alter endothelial and pericyte behaviour, microvascular filtration and extracellular-matrix turnover. Oedema and maladaptive ECM remodelling may increase diffusion distance and reduce interstitial hydraulic conductivity, impairing delivery towards initial lymphatics. Reduced clearance may then retain proteins, inflammatory mediators and tissue water, further disturbing endothelial, immune and matrix signalling. This creates a plausible self-reinforcing hypoxia–ECM–clearance loop.
The important new research proposition is that this state need not be specific to Long COVID.
Long COVID provides a particularly recognisable route through endothelial injury, coagulation abnormalities, persistent inflammatory signalling and tissue remodelling. Non-COVID POTS may potentially reach a similar downstream state through a different initiating pathway: recurrent regional hypoperfusion, venous congestion, abnormal microvascular regulation and repeated tissue hypoxia.
The proposed convergence is: different initiating processes → recurrent microvascular stress/hypoxia → endothelial–pericyte dysfunction → maladaptive ECM remodelling → impaired interstitial and lymphatic clearance → reduced tissue recovery reserve
The paper explicitly presents this as a current research hypothesis rather than a universal mechanism of POTS.
This distinction may prove important. It separates the activating event from the persistent tissue state. SARS-CoV-2 infection, mechanical venous restriction, autonomic vascular dysfunction and reduced perfusion reserve need not have identical initial biology if they ultimately produce similar regional microvascular and interstitial consequences.
It also opens a therapeutic research direction. Low-dose tirzepatide is being explored within this programme not as a direct lymphatic drug and not primarily as a weight-loss intervention, but as a potential modifier of the endothelial–inflammatory–metabolic–ECM environment. The proposition remains investigational: if the downstream tissue state is partly shared between Long COVID and haemodynamically driven POTS, modifying that state might improve recovery reserve even though the original activating events differ.
Thus the third paper moves the series from circulatory physiology into tissue biology.
The same logic extends to venous collateral physiology. A recruited collateral can preserve macroscopic blood movement while still operating at an unfavourable pressure gradient or emptying into a downstream territory that remains resistant. The cavernous–pterygoid pathway becomes an anatomical exemplar of the paper's title: flow may persist without restoration of the pressure-gradient, tissue-clearance or adaptive reserve required for physiological recovery.
Paper 4 — From Tissue Stress to Migraine, Dysautonomia and Chronicity
Head Pressure, Migraine and Dysautonomia then returns to the brain and asks how these upstream hydraulic, haemodynamic and clearance disturbances become clinical disease.
The neurovascular unit provides the critical interface. Repeated cerebral hypoperfusion, venous loading, altered pulsatility and impaired clearance may affect endothelial cells, pericytes, astrocytes, blood–brain barrier function and microvascular regulation. Once these systems become dysfunctional, recovery from the original haemodynamic insult may become progressively less complete.
Migraine is therefore positioned downstream rather than discarded. Established trigeminovascular and CGRP biology explains how migraine is expressed, while haemodynamic, inflammatory, metabolic, cervical and clearance disturbances may influence when that system crosses its activation threshold. This permits conventional migraine biology and the positional observations within this series to coexist without reducing migraine to a venous disorder.
The paper also introduces an important distinction between three levels of chronic disease:
activator → persisting driver → biological perpetuator
These need not be the same process. Infection or trauma may activate illness; a continuing mechanical, venous or preload abnormality may maintain physiological stress; and established neurovascular, autonomic, metabolic, circadian, inflammatory or tissue changes may subsequently perpetuate disease even after the initiating event has diminished.
This has major implications for recovery. Treating tachycardia or migraine alone may suppress downstream expression while leaving the physiological load intact. Conversely, correcting the initiating anatomical lesion may not produce complete recovery once downstream adaptations have become established.
Management therefore becomes a process of restoring reserve, rather than simply removing abnormalities:
identify the dominant upstream load → preserve useful compensation → reduce modifiable drivers → permit haemodynamic, mechanical and tissue recovery → rebuild physiological reserve → treat persistent downstream migraine or autonomic amplification where it remains relevant
Thus the fourth paper moves the model from pathophysiology to chronic disease behaviour and recovery.
Companion Paper — From Anatomical Decompression to Physiological Restoration
Why Stylojugular Decompression May Not Be Enough is deliberately narrower than the four principal papers. It takes one clinically important problem—an anatomically convincing styloid–C1 jugular lesion—and asks why technically successful focal decompression may not restore normal cranial venous physiology.
The answer follows directly from the series. The styloid–C1 corridor is one segment within a longer pathway: jugular bulb → upper IJV/styloid–C1 corridor → mobile cervical IJV → terminal IJV/valve → thoracic outlet and venous angle → central circulation. Resistance may remain at another level, while chronic adaptation may have recruited condylar, vertebral, emissary, cavernous–pterygoid or superficial cervical pathways.
The companion paper therefore distinguishes technical success from physiological success. Technical success means that the intended focal compression has been relieved. Physiological success requires restoration of adequate pressure-gradient and adaptive reserve across the complete drainage network, with reduced dependence on recruited collateral pathways where appropriate.
Its practical rule is simple: do not merely identify a collateral — follow it until you know where it empties.
This paper is retained beside the four principal papers on the website because it translates their shared physiology into a focused intervention question. It is a companion rather than a fifth foundational paper: the four papers define the model; the companion tests what that model means when a focal anatomical lesion is selected for treatment.
What the Four Principal Papers — and the Companion — Now Say Together
The progression of the series can therefore be stated more accurately as:
focal anatomy → distributed network physiology → posture-dependent system loading → collateral recruitment and downstream destination → interstitial and ECM biology → neurovascular adaptation → symptom expression → chronicity, intervention and recovery
Each paper deliberately extends beyond the boundary reached by the one before it.
The jugular-foramen paper shows why the most visible stenosis cannot be understood independently of the network around it.
The upright/supine paper shows why that network cannot be understood independently of the physiological state in which it is tested.
The lymphatic paper shows why preserved vascular flow cannot be assumed to mean normal tissue clearance, and why the disease process may ultimately reside partly in the microvascular–ECM–interstitial environment rather than solely within the vessel.
The integrated head-pressure paper shows why these disturbances cannot be understood independently of the neurovascular unit, autonomic compensation, migraine biology and the progressive loss—and possible restoration—of recovery reserve.
The stylojugular companion paper shows why correction of one anatomically convincing lesion cannot be assumed to restore the physiology of a multilevel, collateralised network, and why intervention must be followed by whole-system reassessment.
Taken together, the papers suggest that the most important abnormality may change over time. What begins as a mechanical or haemodynamic problem can acquire microvascular, interstitial, inflammatory and neurovascular consequences. Conversely, improvement in one layer may expose another limitation that was previously hidden by compensation.
This is why the series does not seek a single lesion or a single treatment.
Its central question is:
Where is adaptive reserve being lost now, what process is continuing to consume it, which compensations are keeping the patient functioning, where do recruited pathways ultimately empty, is the downstream receiving environment capable of accepting that additional load, and what intervention offers the greatest opportunity to restore reserve without destabilising the system?
That question links anatomy, haemodynamics, tissue biology and clinical management across the entire portfolio.
Current Research Direction
The series should be regarded as an evolving research programme rather than a completed disease model.
Several individual components are established anatomy or physiology: posture-dependent venous redistribution, cranial venous collaterals, meningeal and cervical lymphatic pathways, microvascular regulation, ECM–interstitial coupling, established migraine biology and the haemodynamic consequences of orthostasis.
The major research questions lie in their integration. Particular priorities now include:
defining the prevalence and physiological importance of multilevel cranial and cervical venous resistance;
determining which collateral patterns indicate successful compensation, where those pathways ultimately empty, and which patterns instead indicate diminishing reserve;
improving dynamic assessment of vertebral and cervical venous flow;
prospectively distinguishing technical from physiological success after focal venous intervention by assessing the complete pathway, collateral de-recruitment or persistence, downstream resistance and symptom physiology;
characterising the dural and perivascular tissue environment with advanced MRI;
developing more meaningful measures of regional lymphatic and interstitial clearance;
testing whether recurrent regional hypoxia in non-COVID POTS produces measurable endothelial, pericyte and ECM abnormalities comparable with those identified after COVID;
and prospectively examining whether interventions directed at the microvascular–ECM environment—including the current low-dose tirzepatide programme—can alter objective physiology rather than symptoms alone.
prospectively characterising intermittent nasal/posterior-pharyngeal fluid, its biochemical composition and its temporal relationship to head-pressure physiology; and
determining whether recruited emissary, pterygoid and cervical lymphatic pathways provide effective reserve or simply redistribute load into another constrained receiving territory.
The strength of this approach is that each proposition is potentially testable. The model should change as those tests provide better answers.
Clinical and Collaborative Development
This work has developed through longitudinal clinical observation, increasingly sophisticated structural and dynamic imaging, physiological testing and repeated multidisciplinary reassessment. No single investigation or discipline has been sufficient to explain the patterns encountered. Much of the progress has instead occurred when an observation made in one field could be examined from another—when static radiology could be tested dynamically, when vascular abnormalities could be related to mechanical findings, when cranial pathology could be connected to systemic preload, or when preserved vascular flow could be reconsidered in terms of interstitial and lymphatic clearance.
The breadth of the model therefore reflects the breadth of the collaboration. Several colleagues have been particularly important in developing the concepts presented in this series.
Dr Zane Sherif — Radiology and Advanced Vascular Imaging
Dr Zane Sherif, Mermaid Beach Radiology, has been central to the radiological development of the programme. His continuing willingness to question conventional acquisition strategies and refine imaging protocols has allowed increasingly detailed examination of abnormalities that are easily missed when individual anatomical regions are investigated separately.
The development and application of single-acquisition spectral CT angiography and venography has been particularly important. In appropriately designed studies, much of the relevant structural vascular pathology can be examined within a single scan—from the jugular foramen and cervical internal jugular veins through the thoracic outlet and into the abdominal and pelvic circulation. This has been critical to recognition of the multiplicity that characterises the clinical cohort: a conspicuous cranial or cervical abnormality may coexist with thoracic, abdominal or pelvic abnormalities contributing to the same distributed haemodynamic problem.
The major limitation of this extraordinarily useful anatomical overview is equally important: the patient is predominantly examined supine. The study therefore provides a detailed structural map but cannot reproduce many of the posture-, movement- and load-dependent physiological abnormalities responsible for symptoms.
Zane's more recent work with contrast-enhanced black-blood MRI has opened another boundary. Conventional angiography and venography predominantly show the lumen; black-blood techniques permit better interrogation of the dura, vessel wall and surrounding perivascular tissue environment. This has been valuable in assessing pachymeningeal abnormalities associated with suspected CSF-volume depletion and is now contributing to the developing investigation of the jugular-foramen, dural and perivascular interfaces described in this series.
His contribution has therefore extended beyond interpretation of images to the continuing development of the imaging methods required to test the model itself.
Mr Alan Ming — Retinal Photography and OCT
Mr Alan Ming has provided another important window into the cranial circulation through retinal photography and optical coherence tomography (OCT).
The retinal circulation is unusual in providing direct, non-invasive visual access to a neural microvascular bed. Serial retinal photography allows vascular appearances to be followed longitudinally, while OCT provides reproducible structural measurements of the retina and optic-nerve region. This has made repeated assessment possible in patients whose systemic, cranial and neurovascular physiology may be changing with disease activity or treatment.
The importance of this contribution has increased as the research has moved beyond large-vessel anatomy towards endothelial, microvascular and tissue-level dysfunction. CT and MRI provide detailed anatomical snapshots; retinal photography and OCT provide an opportunity for serial objective assessment of an accessible neurovascular compartment.
The retinal findings should not be assumed to provide a direct surrogate for cerebral microvascular or intracranial-pressure physiology. Their value within the programme is that they provide another longitudinal physiological dataset that can be compared with symptoms, vascular imaging, treatment response and the evolving neurovascular hypotheses.
Ms Rylee White and Ms Dani Adey — Dynamic Vascular Sonography
The limitations of supine structural imaging made development of a complementary dynamic technique essential. Ms Rylee White and Ms Dani Adey have been central to developing and refining dynamic vascular sonography in which flow, rather than anatomy alone, is examined during physiological provocation.
Their work has allowed vascular behaviour to be assessed during changes in posture, head and neck position, arm elevation and other manoeuvres relevant to the patient's symptoms. This has been especially important in the vertebral venous system. Normal transition to the upright position should reduce jugular dominance and recruit vertebral, condylar and other posterior pathways.
Demonstration of reduced, absent, intermittent or retrograde vertebral venous flow therefore provides information that cannot be obtained from a conventional supine CT or MR study.
Dynamic sonography has similarly helped characterise position-dependent IJV restriction, thoracic-outlet vascular compression and the behaviour of collateral pathways.
This creates an important partnership between imaging modalities: spectral CT/MR defines the anatomy → dynamic sonography determines what happens to flow when that anatomy is physiologically challenged.
Rylee and Dani's work has consequently been fundamental to the transition of the programme from a predominantly structural model to a dynamic haemodynamic model.
Mr Sascha Halpin and Mr Brendan McLeod— Cranio-Cervical and Thoracic Outlet Mechanics
Mr Sascha Halpin has been central to the clinical development of the cranio-cervical, cervical-jugular and thoracic-outlet components of the work, in association with Mr Brendan McLeod
Their detailed assessment of upper-cervical mechanics, suboccipital function, scapular control and thoracic-outlet behaviour has helped connect abnormalities demonstrated by imaging and sonography with the mechanical circumstances in which symptoms and flow disturbance occur.
A particularly important contribution has been the recognition that apparently abnormal muscular recruitment may represent compensation rather than primary pathology. In mechanically vulnerable or hypermobile patients, increased suboccipital, cervical or scapular recruitment may be contributing to stability even when the recruited tissue itself becomes painful or symptomatic. Simply releasing what appears tight may therefore remove part of an adaptation without correcting the reason it was required.
This observation has become much broader than a manual-treatment principle. It contributed to one of the central concepts of the entire series: the visible abnormality and the physiological driver are not necessarily the same thing.
Sascha's work has also helped connect the upper cervical region with the thoracic outlet, reinforcing the need to follow jugular and mechanical physiology through the neck rather than treating the styloid–C1 region as an isolated lesion.
Ms Brooke Wade — Intra-Abdominal Pathology and Its Cranial Connections
Ms Brooke Wade has been particularly important in extending the work into intra-abdominal mechanical and vascular pathology and in recognising how abnormalities below the diaphragm can influence the cranial physiology being investigated above it.
The recurring coexistence within the cohort of MALS, SMA compression, Nutcracker physiology, pelvic venous congestion, May–Thurner anatomy and related abnormalities has increasingly challenged the concept that cranial symptoms can be understood by examining the head and neck alone.
These abnormalities may influence splanchnic and pelvic venous capacitance, renal haemodynamics, autonomic activation and systemic venous return. Their physiological importance may therefore be magnified in a patient whose cerebral perfusion or cranial drainage is already operating with reduced reserve.
Brooke's work has helped establish a critical principle running through the later development of the series: cranial drainage cannot be separated from the circulation supplying and receiving it.
The head-pressure model consequently extends through the thorax into the abdomen and pelvis, where apparently separate compression syndromes may contribute to the systemic preload and autonomic environment against which cranial adaptation must operate.
Dr Mark Westaway — Whole-Body Mechanical Integration
Dr Mark Westaway has contributed an important broader perspective on spinal, postural and whole-body mechanical integration.
His work has helped prevent the developing model from becoming excessively focused on individual vascular lesions. Rotational spinal abnormalities, thoracic mechanics, connective-tissue vulnerability, altered loading and compensatory movement patterns may affect several components of the physiological system simultaneously.
This becomes particularly relevant in a cohort in which abnormalities are commonly multiple. A structural lesion that appears relatively modest when considered independently may acquire substantial physiological importance when reserve has already been consumed elsewhere.
Mark's contribution has therefore reinforced the whole-system approach: the task is not simply to catalogue abnormalities but to understand how the patient's complete mechanical environment influences vascular function, preload, compensation and recovery.
His clinical observations around the TMJ and pterygoid region have also become relevant to the newer cavernous–pterygoid work. Because the pterygoid plexus lies within a mechanically active masticatory region and communicates with both intracranial and downstream facial/retromandibular venous networks, these observations provide a testable clinical hypothesis about local mechanical modulation of collateral reserve; they are not presented as proof that manual or dental intervention alters cavernous-sinus drainage.
Ms Michelle Hill — Lymphatic, Interstitial and ECM Physiology
Ms Michelle Hill has been central to one of the most recent and important expansions of the programme: from vascular flow into lymphatic, interstitial and extracellular-matrix physiology.
Her observations during anatomically directed manual lymphatic treatment have repeatedly emphasised that movement of fluid is not synonymous with successful clearance. Mobilising fluid upstream may be ineffective or may aggravate symptoms if downstream lymphatic, venous or mechanical conditions do not permit effective emptying. This has contributed directly to the concepts of treatment sequencing, site-directed drainage and preservation of compensatory pathways.
Her clinical observations have also reinforced the importance of gentleness. The cranio-cervical region may contain recruited venous collaterals immediately beside muscles providing compensatory mechanical stability. Treatment intended to improve clearance must therefore avoid simultaneously compressing a recruited vascular pathway or removing a stabilising muscular adaptation. This principle is already reflected in the head-pressure work, where treatment is directed according to the anatomical level of restriction rather than applied as a generic lymphatic technique.
Michelle's contribution has become still more important as the lymphatic paper has moved upstream from the collecting lymphatic vessel into the interstitial and ECM compartment. The developing research model now asks whether regional hypoxia, endothelial–pericyte dysfunction, altered microvascular filtration and ECM remodelling may impair interstitial transport before fluid ever reaches the initial lymphatic system. The new convergence hypothesis proposes that Long COVID and non-COVID POTS may reach such a tissue state through different initiating pathways.
This has opened an important new boundary for the programme: the vessel can no longer be considered independently of the tissue through which oxygen, metabolites and fluid must move.
A Collaborative Research Model
These contributions are most powerful when considered together rather than separately.
Zane Sherif provides the high-resolution structural map and is extending imaging beyond the lumen into the dural and perivascular environment. Alan Ming provides serial retinal photography and OCT, creating a repeatable window into an accessible neurovascular compartment. Rylee White and Dani Adey determine how vascular flow actually behaves when posture and movement challenge the static anatomy. Sascha Halpin and Brendan McLeod define the cranio-cervical and thoracic mechanical environment in which those vessels operate. Brooke Wade connects cranial physiology with abdominal and pelvic abnormalities capable of altering systemic preload and autonomic load. Mark Westaway provides broader spinal and whole-body mechanical integration. Michelle Hill extends the system beyond vascular flow into interstitial, lymphatic and ECM clearance and contributes to understanding how that physiology can be approached therapeutically without disrupting compensation.
This interaction between disciplines has been fundamental to the development of the work. A finding on CT can be tested dynamically with ultrasound; an unexpected flow abnormality can be reconsidered in light of cervical mechanics; cranial findings can be interpreted against abdominal and systemic preload abnormalities; retinal changes can be followed longitudinally; and persistent symptoms despite apparently preserved vascular flow can now be examined in terms of interstitial, ECM and clearance physiology.
Many of the most important advances have occurred precisely where the observations of one discipline could not be adequately explained until viewed through another.
The broader POTS and Long COVID research programme has benefited from additional colleagues, including Mr David Haynes and Dr Valerio Vittone (PhD), whose particular areas of contribution extend beyond the principal focus of these four papers. Their work forms part of the wider collaborative environment from which the present series has developed.
The Head Pressure and Migraine portfolio should therefore be regarded not as the product of a single specialty or a completed theory, but as an evolving multidisciplinary research programme. Clinical observation generates questions; anatomy identifies possible constraints; advanced imaging and dynamic sonography test them; mechanical assessment examines the environment in which they occur; and longitudinal physiological and therapeutic observations determine whether the proposed relationships remain credible.
The common objective is not simply to find abnormalities. It is to determine where physiological reserve is being consumed, what is driving that loss, which abnormalities and collateral pathways are compensatory, where those compensations ultimately deliver their load, whether the receiving environment can accept that load, how the different levels of the system interact, and what can be altered without destabilising the adaptations that are still preserving function.
That principle—understand the whole system before intervening, then reassess the system after it has changed—has become the methodological foundation of the series.
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