JH is a 35-year-old male, s/p kidney transplant who presented to the hospital with diarrhea and dehydration. Medical comorbidities include hypertension and diabetes mellitus. During the course of his admission, he was treated with supplementation of IV fluids, electrolytes, and monitored closely for renal function. He awoke one morning with weakness of the left arm. He also had mild left shoulder pain and did not feel there was any difference in sensation. On examination, he had diffuse weakness involving the left arm involving all muscle groups with normal reflexes everywhere. Sensory examination was normal.

The history and physical examination did not yield an immediate solution. The weakness was too diffuse to be attributed to the commonest reason—radial palsy. Given the sudden onset, diffuse weakness and risk factors of kidney disease, high blood pressure, and diabetes mellitus the most pressing concern was for a stroke. An urgent MRI Brain was requested. The patient was beyond all windows for IV or intra-arterial tissue plasminogen activator (tPA). The patient was initially seen in the afternoon around 3:00 p.m. The MRI Brain was planned within the next 2–3 h as soon as scheduling permitted. If this was negative, the plan was to proceed with an MRI of the Cervical Spine to see if this was due to lesions of the spinal cord like transverse myelitis. If this was negative as well, the plan was to perform an EMG to look for brachial plexus lesions. The problem was classified as Open-Acute/Urgent which necessitated a solution had to be found in hours.

By 7:30 p.m., MRI Brain was performed. The MRI Brain was reviewed later that evening and was found to be normal. No evidence of stroke was found. Proceeding down the algorithm mentioned above, MRI C Spine was ordered urgently. While waiting for this, a thorough review was performed, including consideration of the rare and obscure (West Nile infection, CMV infection etc.) which though possible given the immunosuppression were obviously not the cause here. MRI C Spine was completed around 10:00 p.m. and was normal as well.

Since no solution had been apparent by 10:00 p.m., a second examination was performed of the patient around midnight, approximately 8 h since initial examination. By now, the patient had woken from a nap and was paralyzed below the neck. Breathing, eye movements were normal. Curiously speech and sensation were normal and he had no urinary or fecal incontinence. Since no firm hypothesis was formed, reevaluating the entire data looking for new clues became the priority. An intense review of all data to date performed around 1:00 a.m. showed a fact that had been overlooked in the afternoon, a low potassium level of 2.8 meq/L. An urgent repeat level was ordered which showed it had slid lower to 2.0 meq/L with the potential for life-threatening cardiac arrhythmias. This was not suspected or sought aggressively initially since low potassium is not a common consideration in focal weakness.

The solution had been determined but only just in the nick of time. An urgent EKG showed findings of severe hypokalemia such as U waves and frequent ectopics. The patient was immediately transferred to the ICU. Potassium was urgently replenished with complete recovery. The root cause of the problem was identified as loss of potassium from diarrhea and changing acid base balance.

This case would have been fatal if the hunt for the solution had been delayed until next morning. Therefore, a problem status has to be defined and the V model has to be intensely applied until the problem is solved within the acceptable timeframe. As discussed above, approaching this as a process has the advantage of imposing intermediate processing times for each step of the diagnostic approach with alternate ideas being explored in a time bound way driven by the urgency and importance of solving the problem.

WH is a 60-year-old male with symptoms of bilateral arm weakness. He did not remember when the problems started, it could have been many years ago, but it progressed very slowly. The first symptoms he noticed were difficulty retrieving objects from shelves. He had no difficulty with closing his eyes, speaking, chewing, swallowing, breathing, or walking. He had no problems with sensation. On physical examination, he had severe weakness about the shoulder. The mildest movements would lead to displacement of the shoulder blade so that the deltoid muscle was rendered mechanically ineffective. The deltoid muscles themselves showed only mild weakness. The serratus anterior and rhomboids were severely wasted and weak with prominent scapular winging. The face, forearm, hands, and legs were normal. Sensation was normal. No diagnosis had been arrived at to-date. FTA performed for this case is shown in Fig. 7.3. Based on this analysis, the prominent scapular winging an initial working diagnosis of Facioscapulohumeral dystrophy (FSHD) was considered [4]. Neuropathic etiologies which can cause scapular winging, (usually in a scapuloperoneal pattern) include Davidenkow’s syndrome [5]. A gene test for FSHD (D4Z4 repeats on chromosome 4q35) was requested [6], patient was provided a return appointment in the next 4 months as results of diagnostic testing were obtained. The patient was also set up for EMG.

The patient underwent an EMG performed by another physician which confirmed a myopathic process. Genetic test for FSHD was negative which can happen in ~2 % of cases [4]. This necessitated going back to steps 3, 4 to examine alternative hypotheses from the FTA and direct further testing. Since the gene test was negative, a muscle biopsy was requested based on raw EMG data. Though clinically weak, commonly biopsied muscles such as biceps were reported to be normal on EMG. Based on EMG description, the findings in the infraspinatus were interpreted to be reasonable for biopsy. The biopsy was however indeterminate since the sample was essentially end stage muscle. Since the patient lived far away, the muscle biopsy was performed concomitantly with blood testing for Acid Maltase (Pompe’s disease) activity level, which is considered a rare cause of scapular winging [6]. Pompe’s disease is classically described to produce limb girdle weakness and respiratory weakness which was not the case here [6]. The Acid Maltase activity level was low confirming this to be an unusual presentation of Pompe’s disease. Pompe’s disease can cause respiratory weakness but is treatable with enzyme replacement therapy, therefore it was a surprising outcome [7]. While Acid Maltase deficiency itself is a very rare disease even for most skilled neuromuscular clinicians, this presentation of it is even rarer. Application of this rigorous process yielded a solution instead of attributing his problem to a variation of FSHD. Pulmonary Function tests showed moderate diaphragmatic weakness.

This section discusses creating ancillary processes for unexpected information encountered during the diagnostic process in steps 3 and 4 which are not the core area of the physician who initiated the process. Teamwork in the care of complex multisystem patients is discussed separately in subsequent chapters, this example guides a process driven approach to information unexpectedly encountered while traversing the V.

Advances in imaging technology and laboratory diagnostic medicine have created immense amounts of ancillary information which are discovered serendipitously during the course of searching for something else. A major problem has been the lack of a rigorous disciplined approach to handling such unexpected information when they are not the focus of the ordering clinician. Numerous examples abound in virtually all areas of medicine with radiology being the common denominator in most instances. Successful modern management in industry involves defining problems and subproblems and assigning responsibility appropriately. Such details must not be omitted and must be addressed by applying the correct skills. For each thread of unsolved information, a process must be defined and responsibility fixed so that a problem does not get neglected and become incurable, especially in those happy instances when a long lead time would have benefitted treatment. Assigning responsibility is key. The following example illustrates this principle:

MA is a 65-year-old male smoker with symptoms of double vision, fatigue, and weakness for several months. Strokes, aneurysms were excluded by normal MRI Brain scans. He was diagnosed with myasthenia gravis. The diagnosis was fairly straight-forward, blood work was positive for the antiacetylcholine receptor-binding antibodies (AchR-Binding antibody) which established the diagnosis. Since a percentage of cases are related to a tumor of the thymus gland located in the chest, a CT scan of the chest usually follows this diagnosis. In MA’s case, it was anticipated that his treatment would involve suppression of the immune system with steroids such as prednisone. For this reason, precautions were taken to check vitamin D levels, thyroid function, establish whether he was diabetic or not and perform a skin test for tuberculosis along the lines of FMEA discussed in Chap. 4.

The CT chest was negative for thymoma, but showed pulmonary nodules which are a frequent finding in CT scans of the chest as scanners became better. Blood testing showed he was already diabetic without knowing it. Thyroid function testing revealed hypothyroidism. Additionally, vitamin D levels were low. Given this constellation of abnormalities, responsibility and follow through were defined for the subproblems:

Therefore, what started out as one symptom had multiplied into four problems—lung nodules, diabetes mellitus, hypothyroidism, and myasthenia gravis. Each required meticulous attention and follow through which was beyond the scope of one person. Defining a problem list where each of these entities is enumerated with an appropriate physician taking responsibility for each problem was defined. In a sense, it is similar to the graph theoretic structure described earlier except the idea is not to define an edge between the nodes but to establish a thread of responsibility and follow through. The advantage with defining such problem lists is that every subproblem gets labeled and gets adequate attention, expertise, and follow through. The recent requirement for creating, maintaining, and updating such problem lists is a step in this direction.